Making an X-10 lamp module immune to dimming
Robert Green
does anyone have any suggestions on how to accomplish it? I have lots of
extra modules to experiment on, and it would seem that there's a control
line that tells the triac how much to "chop" that could be modded to always
run full tilt. That way, a brighten or dim command wouldn't affect them.
I found the schematic at Dr. C's site:
http://www.edcheung.com/automa/lm465.gif
He also did some work attempting to make the switch smarter
http://www.edcheung.com/automa/iwsp.htm
by dropping in his own PIC, but was overtaken by events and commercial units
becoming available that did what he wanted.
It looks like the triac, BTA10-400C, gets controlled by pins 6 and 8 of the
78561 microcontroller. The trick is to make it deaf to only bright and dim,
not on and off.
--
Bobby G.
Bill Kearney
"Robert Green" <ROBERT_G...@YAH00.COM> wrote in message
news:8qOdnUpVj9L2ONvV...@rcn.net...
> Anyone know of a mod to make an X-10 lamp module immune to dimming?
As opposed to just using an appliance module?
Robert Green
news:cp-dnWMoifQbY9vV...@speakeasy.net...
Yes, for quite a few reasons.
1) Most importantly they do not clack
2) I have about 40 of them doing nothing that I would like to put in service
3) they can be used for some CFL's as long as they aren't dimmed
4) I seem to have less of a flashing and phantom restart problem using them
with CFL's.
5) They respond to ALL LIGHTS ON and OFF, appliance modules don't
--
Bobby G.
BruceR
http://www.idobartana.com/hakb/
Scroll down on the left to "Lamp Modules" and the sub heading "Making a
Silent Appliance Module" and start warming up your soldering iron!
Ido's site is THE repository for X10 mods!
Jeff Volp
respect to powerline zero crossings determine the brightness. It is not
clear how they adjust the phase, but it is probably done by some sort of
timer in the IC whose count for each half cycle is a function of the dim
level.
Since older lamp modules come on at full brightness, the problem only occurs
if they are manually sent dim commands. Either just don’t do that, or put
them on their own housecode where they can’t be directly accessed. Then
have your Ocelot or HV map manual commands to only ON/OFF on that housecode.
The macro can also handle the “ALL” issues.
We have a bunch of lamp modules that are only used for ON/OFF control. Most
power CFLs, but one runs our hot-water recalculation pump. Can you imagine
CLACK - - - -CLACK every 15 minutes from an appliance module?
Jeff
"Robert Green" <ROBERT_G...@YAH00.COM> wrote in message
news:KPKdnX04IPMWktrV...@rcn.net...
BruceR
Appliance Module that they claim to be 80% quieter than the X10 one. I
have some and they are quiet enough so that you wouldn't notice it
unless the room were very quiet and you were close to it.
Robert Green
news:4847176b$0$4262$4c36...@roadrunner.com...
> The instructions for the mod you seek can be found here:
> http://www.idobartana.com/hakb/
> Scroll down on the left to "Lamp Modules" and the sub heading "Making a
> Silent Appliance Module" and start warming up your soldering iron!
>
> Ido's site is THE repository for X10 mods!
Thanks! I saw that and it's close but no ceegar. One of the reasons to do
this is so that lamps CAN respond to all lights on and off. I suppose in
the spirit of "Thomas Edison" whose strategy was often "try anything you can
think of" I'll try cutting the control lines from the PIC to the triac to
see what happens. I had hoped to avoid using virtual housecodes as Jeff
suggested to filter the dim and bright commands. It just seemed to me that
the bright and dim control circuit paths might be separate enough from the
on off circuitry that one could be neutered without affecting the other. It
would take a far smarter person than I to determine where to snip based on
circuit analysis, even with Mr. Bloom's helpful schematic. However, reading
through Ido's explanation of his mods, I've got a few more clues as to how
the module operates.
--
Bobby G.
Dan Lanciani
| "BruceR" <razr...@NOgmailSPAM.com> wrote in message
| news:4847176b$0$4262$4c36...@roadrunner.com...
| > The instructions for the mod you seek can be found here:
| > http://www.idobartana.com/hakb/
| > Scroll down on the left to "Lamp Modules" and the sub heading "Making a
| > Silent Appliance Module" and start warming up your soldering iron!
| >
| > Ido's site is THE repository for X10 mods!
|
| Thanks! I saw that and it's close but no ceegar. One of the reasons to do
| this is so that lamps CAN respond to all lights on and off.
The described modification does not affect the module's response to all
lights on. If you actually have lamp modules that respond to all lights
off (none of mine do) it won't affect that either.
| I suppose in
| the spirit of "Thomas Edison" whose strategy was often "try anything you can
| think of" I'll try cutting the control lines from the PIC to the triac to
| see what happens.
Nothing useful will happen...
| It just seemed to me that
| the bright and dim control circuit paths might be separate enough from the
| on off circuitry that one could be neutered without affecting the other.
There is but one path.
Dan Lanciani
ddl@danlan.*com
Bill Kearney
> 2) I have about 40 of them doing nothing that I would like to put in
> service
> 3) they can be used for some CFL's as long as they aren't dimmed
> 4) I seem to have less of a flashing and phantom restart problem using
> them
> with CFL's.
Cue Dave for this anti-CFL rants...
Robert Green
news:08F1k.18467$102....@bgtnsc05-news.ops.worldnet.att.net...
> IC pin 8 is the output that drives the triac. The delay of that pulse
with
> respect to powerline zero crossings determine the brightness. It is not
> clear how they adjust the phase, but it is probably done by some sort of
> timer in the IC whose count for each half cycle is a function of the dim
> level.
>
> Since older lamp modules come on at full brightness, the problem only
occurs
> if they are manually sent dim commands. Either just don’t do that, or put
> them on their own housecode where they can’t be directly accessed. Then
> have your Ocelot or HV map manual commands to only ON/OFF on that
housecode.
> The macro can also handle the “ALL” issues.
Since we have had two seriously smokin' CFL failures that filled the house
with acrid melting plastic smoke, I am afraid to leave the "don't dim" rule
in the hands of operators or my weak HA programming skills. Another CFL
"Burning Man" tribute would have some serious SAF repercussions. It's just
too easy to press DIM with too many different types of controllers, from
maxi's to Palmpads to keychains when you don't mean to. Putting all the
lights on phantom codes would make the HV or CPU-XA a central failure point
I'd rather not have given my mediocre programming skills. It's not the end
of the world if this isn't doable, but it would be awfully nice to put the
huge box of them to use and to get rid of the clacks. I really don't want to
go the virtual housecode route, but that seems to be the only option if I
can't make the modules themselves deaf to bright and dim commands.
I believe the first test will just be to simply disconnect pin 8 from the
control line. Hopefully it will be easy to rebridge if that turns out not
to work. Also, hopefully, it won't incinerate itself after snipping that
line. I guess I can trot out the old 20mm ammo box I have for containment
of explosive experiments - well, maybe just leave it on a fireproof surface
to test . . .
> We have a bunch of lamp modules that are only used for ON/OFF control.
Most
> power CFLs, but one runs our hot-water recalculation pump. Can you
imagine
> CLACK - - - -CLACK every 15 minutes from an appliance module?
That would have very bad SAF. It's good to know I'm not the only one that
wants to use lamp modules for CFL's and other uses. I assume you're using a
virtual housecode to filter out any "bad presses" that would have resulted
in sending a DIM to the pump controller lamp module. I really would like
the ALL LIGHTS ON/OFF command to work with CFLs. Also, I don't know whether
it's dumb coincidence, but my N:Vision 23W flood does not relight or flash
on a lamp module but does when connected to an appliance module. The
relighting and flashing is very bothersome. Come to think of it, that's
probably why you have very little trouble with relighting and flashing CFL's
but I do - you're running them from lamp modules and I have been using
appliance modules. The lightbulb over my head has just lit up!
Thanks for the input, Jeff.
--
Bobby G.
Jeff Volp
> I believe the first test will just be to simply disconnect pin 8 from the
> control line. Hopefully it will be easy to rebridge if that turns out not
> to work. Also, hopefully, it won't incinerate itself after snipping that
> line. I guess I can trot out the old 20mm ammo box I have for containment
> of explosive experiments - well, maybe just leave it on a fireproof
> surface
> to test . . .
Whoops, that was a typo before. Pin 8 is used for the local control.
Snipping that will only disable local control. Pin 6 drives the triac.
That line is essential. If snipped there will be no on/off control at all.
The dimming phase control is inside the IC.
It might be possible to extend the pulse coming out of the IC so that if
there is ANY pulse at all, the transistor will remain on through the
beginning of the next cycle so the unit will switch on right after the zero
crossing.
Jeff
isw
"Jeff Volp" <Jeff...@msn.com> wrote:
> IC pin 8 is the output that drives the triac. The delay of that pulse with
> respect to powerline zero crossings determine the brightness.
Actually, I think it's pin 6 that drives the triac, via C337 (assuming
that schematic is correct).
A while back, I hacked around in those controllers. Here are some of my
notes:
"The IC generates a series of pulses, with at least one always present,
near but before the zero-crossing (i.e. even at "off" the triac is
triggered, just very late in the half-cycle).
"As the "brighten" signal is sent, the pulse first slides earlier in the
half-cycle, and then multiple pulses appear, with more and more as full
on is approached."
What I wanted was a single duration-modulated pulse (wider for brighter,
of course), and here's how I got it:
1) Add a signal diode (1N4148) in series with the signal from IC pin 6
(i.e. cut the trace and hook it between the two points "B" on the
schematic, cathode towards the transistor)
2) Change the 2.2 k resistor to 12 k.
3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode of
the diode to V-
4) Change the 330 ohm resistor to 2.2 k
--
As an interesting side-note, connecting the LED of a *high voltage*
optical isolator in series between the 39 ohm resistor and the collector
of C337 will give a safely isolated version of that pulse (or the
original pulse bursts, if that's what you want).
--
Now, to go on to an "on or off" version, here's what I'd try (Note that
I haven't done it, so I'm just guessing here):
Replace transistor C337 with a very high-beta Darlington transistor
(that will make for a much narrower "linear zone" between cutoff and
saturation.
Increase the size of the added 0.1 mfd. capacitor until the base signal
to C337 is integrated to a DC level (which will rise as the pulse
widens).
So now, the transistor should move from off to on at some fairly well
defined pulse width (adding some feedback to make the C337 act like a
Schmitt trigger will help).
IF this works, it will almost certainly have some "lag" because that cap
has to charge or discharge before the triac gate signal can change.
It'll surely take some fiddling around to find optimum values for some
of the added parts (but having that optically-isolated signal to look at
will make the process a whole lot safer). Maybe a cap from the collector
of C337 to V- would help. Maybe adding a couple of forward-biased diodes
or a low-voltage zener in series with C337's base (to increase the
voltage where it starts to turn on, something the Darlington also does).
I'd try it both with and without that 1N4148, too.
CAUTION. WARNING. If anything you do as a result of trying to follow
these notes gets you injured or dead, or kills your cat, or burns your
house down, I'll be very sorry, but I will *not* be responsible. I'm a
professional engineer who has been doing things like this (or worse) for
well over forty years. You get to decide for yourself whether your level
of competence is sufficient for you to tackle it.
Isaac
Jeff Volp
earlier post.
I was thinking along the lines of a diode and cap too. I have not looked at
that signal myself. However, if there is always a pulse there, a simple
circuit may not be sufficient. A pulse late in the cycle fed through a
diode - capacitor network into the transistor would trigger the triac early
in the next cycle. Or, does that pulse go away completely when the module
is OFF?
Jeff
"isw" <i...@witzend.com> wrote in message
news:isw-A19801.2...@newsgroups.comcast.net...
Dan Lanciani
How much current does the triac's gate draw? I'd be worried that the
module's power supply can't handle leaving the transistor on for long.
These supplies are always by design near their limit.
The $1 modification avoids the power problem by getting the gate drive
directly from the line/load. The author appears to know what he is doing
so I think if there were a simpler way he would have found it. And it's
already pretty simple...
Dan Lanciani
ddl@danlan.*com
isw
"Jeff Volp" <Jeff...@msn.com> wrote:
> Your are correct about transposing pins 6 & 8. I caught that myself in an
> earlier post.
>
> I was thinking along the lines of a diode and cap too. I have not looked at
> that signal myself. However, if there is always a pulse there, a simple
> circuit may not be sufficient. A pulse late in the cycle fed through a
> diode - capacitor network into the transistor would trigger the triac early
> in the next cycle.
Not if you get the time constant right.
> Or, does that pulse go away completely when the module is OFF?
According to my notes (several years old), there is always at least one
pulse there. The diode and capacitor, plus changes to the values of the
resistors, will integrate the pulse train into a single pulse that gets
wider as the dimming moves towards full on (the first pulse in the train
is always at the time the triac *should* fire; maybe all the others are
just "insurance" or maybe it's just the way that chip works. When the
unit is at "full off" that single pulse is very narrow, so an RC
integrator works pretty well (at least, it worked for me).
--
Side note
I took the optically isolated integrated pulse, and integrated it again
to a DC level, then fed it to a National LM-3914 Dot/Bar Display Driver.
I was looking for a cheap way to control a lot of off-on devices from a
single X-10 unit. I figured that by counting "brighten" pulses, I could
make whichever of the 3914 outputs hot that I wanted. Problem was, the
X-10 unit was not consistent from one time to the next, so everything
worked just fine except that say, 5 pulses, would not always make the
same output hot; sometimes the one "before" and sometimes the one
"after". Bummer.
--
So based on all that, I think that it is possible to get a single pulse
that gets wider as "brighten" commands are sent, even though there will
be some inaccuracy in just how wide that pulse is.
Then if you set up some sort of "thresholding" (like a Schmitt trigger
or an overdriven high-gain stage), the triac will either get a drive
signal, or it will not.
Isaac
isw
ddl@danlan.*com (Dan Lanciani) wrote:
> In article <upJ1k.19034$102...@bgtnsc05-news.ops.worldnet.att.net>,
> Jeff...@msn.com (Jeff Volp) writes:
> | "Robert Green" <ROBERT_G...@YAH00.COM> wrote in message
> | news:hOWdnZPUEpdFotrV...@rcn.net...
> |
> | > I believe the first test will just be to simply disconnect pin 8 from the
> | > control line. Hopefully it will be easy to rebridge if that turns out
> | > not
> | > to work. Also, hopefully, it won't incinerate itself after snipping that
> | > line. I guess I can trot out the old 20mm ammo box I have for
> | > containment
> | > of explosive experiments - well, maybe just leave it on a fireproof
> | > surface
> | > to test . . .
> |
> | Whoops, that was a typo before. Pin 8 is used for the local control.
> | Snipping that will only disable local control. Pin 6 drives the triac.
> | That line is essential. If snipped there will be no on/off control at all.
> | The dimming phase control is inside the IC.
> |
> | It might be possible to extend the pulse coming out of the IC so that if
> | there is ANY pulse at all, the transistor will remain on through the
> | beginning of the next cycle so the unit will switch on right after the zero
> | crossing.
As I said, and according to my notes, there is *always* at least one
pulse there, even if the unit is fully dimmed.
> How much current does the triac's gate draw? I'd be worried that the
> module's power supply can't handle leaving the transistor on for long.
> These supplies are always by design near their limit.
There's already a current limiting resistor there (39 ohms). One could
try increasing it, but if the drive current gets too low, the triac may
not trigger completely, and could dissipate more heat than would be a
good idea. Based on my memory of the pulse train that drives the triac,
I'd say that with the circuit I suggested, the integrated gate current
is no more than two or three times what it is in the original circuit.
Isaac
Robert Green
> | > The instructions for the mod you seek can be found here:
> | > http://www.idobartana.com/hakb/
> | > Scroll down on the left to "Lamp Modules" and the sub heading "Making
a
> | > Silent Appliance Module" and start warming up your soldering iron!
> | >
> | > Ido's site is THE repository for X10 mods!
> |
> | Thanks! I saw that and it's close but no ceegar. One of the reasons to
do
> | this is so that lamps CAN respond to all lights on and off.
>
> The described modification does not affect the module's response to all
> lights on. If you actually have lamp modules that respond to all lights
> off (none of mine do) it won't affect that either.
You're correct. At first glance I thought he was talking about putting a
solid state relay inside an appliance module to eliminate the clack. After
your comment, I went and tested the modules I have and while the wall
switches respond to All Lights ON/OFF, the lamp modules don't. They only
respond to All Lights ON. Bummer. Well, that makes the project somewhat
less attractive. At least the All Lights ON command is more useful to me
than All Lights Off would be. How is that the X-10 security system flashes
the house lights? Do lights on lamp modules turn on but not off? My memory
seems to be that all lights turned on and off, but I could easily be
mistaken. I think it's Mad Cow disease setting in.
> | I suppose in
> | the spirit of "Thomas Edison" whose strategy was often "try anything you
can
> | think of" I'll try cutting the control lines from the PIC to the triac
to
> | see what happens.
>
> Nothing useful will happen...
Well, such is the way of the "grunt and crank" method. I would have at
least re-discovered the local sense mod for lamp modules. My whole premise
was based on a misunderstanding of how triacs work. I thought they were
merely high speed electronic relays.
> | It just seemed to me that
> | the bright and dim control circuit paths might be separate enough from
the
> | on off circuitry that one could be neutered without affecting the other.
>
> There is but one path.
It's become apparent that the triac can only do its magic when synched to
the zero crossing. That became clear as I read through the modification
details. Being a non-electrotechie, I assumed that a triac just passed
current until the trigger voltage was no longer applied, like a solid state
relay. I also thought its other "claim to fame" was how incredibly quickly
it could switch and that tiny triggering currents could control much large
currents. I just had hoped like the local sense problem, a simple snip
would do it. Now it seems like the simplest mod is to extract the ZC data,
optically isolate it and then use it to inject the synchronizing signal into
the triac, assumable for it be able to reverse its polarity and pass current
flowing in the opposite direction for each half cycle of the AC line.
I've just disassembled a lamp module and it looks as though it's not as
crowded as I recall. I have enough of these to practice on so that when the
weather turns hot, I might just attempt to undertake the modification. I'd
still rather just clip a resistor lead to fix them but the discussion has at
least educated me as to why that's likely to have no effect.
Perhaps you could be kind enough to explain what would happen if the line to
the triac gate was high all the time. Would it conduct only on the first
half cycle, or not at all or would the magic smoke escape? (-:
--
Bobby G.
Robert Green
> "Robert Green" <ROBERT_G...@YAH00.COM> wrote in message
> news:hOWdnZPUEpdFotrV...@rcn.net...
>
> > I believe the first test will just be to simply disconnect pin 8 from
the
> > control line. Hopefully it will be easy to rebridge if that turns out
not
> > to work. Also, hopefully, it won't incinerate itself after snipping
that
> > line. I guess I can trot out the old 20mm ammo box I have for
containment
> > of explosive experiments - well, maybe just leave it on a fireproof
> > surface
> > to test . . .
>
> Whoops, that was a typo before. Pin 8 is used for the local control.
> Snipping that will only disable local control. Pin 6 drives the triac.
> That line is essential. If snipped there will be no on/off control at
all.
> The dimming phase control is inside the IC.
As I understand it now, the pulse to the triac has to occur twice every
cycle and has to be alternatingly negative and positive to allow each half
of the AC cycle to pass. The dimmer does its magic by narrowing the width
of that pulse - shorter means less power gets to the device and its dimmer.
As I said to Dan, I thought a triac was just a very fast solid state relay.
> It might be possible to extend the pulse coming out of the IC so that if
> there is ANY pulse at all, the transistor will remain on through the
> beginning of the next cycle so the unit will switch on right after the
zero
> crossing.
It sounds like the mod that uses the alternistor and the optoisolator does
just that. It seems that the optoisolator extracts the ZC data and then the
additional circuitry creates its own full width pulse independent of
whatever length pulse comes out of the IC. So if the module was dimming the
output, it wouldn't matter because that pulse is driving a latching circuit
that stays on until the next ZC, correct?
--
Bobby G.
Robert Green
> "Jeff Volp" <Jeff...@msn.com> wrote:
>
> > IC pin 8 is the output that drives the triac. The delay of that pulse
with
> > respect to powerline zero crossings determine the brightness.
>
> Actually, I think it's pin 6 that drives the triac, via C337 (assuming
> that schematic is correct).
>
>
> A while back, I hacked around in those controllers. Here are some of my
> notes:
>
> "The IC generates a series of pulses, with at least one always present,
> near but before the zero-crossing (i.e. even at "off" the triac is
> triggered, just very late in the half-cycle).
>
> "As the "brighten" signal is sent, the pulse first slides earlier in the
> half-cycle, and then multiple pulses appear, with more and more as full
> on is approached."
Does that mean that the pulse width does not vary, but that the level of the
light is determined by how many pulses of a fixed width are received during
an AC cycle? I assume that would me they are obviously much shorter in
duration than 1/2 the AC cycle. It sounds like they are "rechopping" the
pulse into smaller pulses and that they aggregate to give the desired end
level. I am not explaining that well, I fear. It seems like there are two
pulse aggregations, a wheel within a wheel Ixion sort of thing.
> What I wanted was a single duration-modulated pulse (wider for brighter,
> of course), and here's how I got it:
Why did you want to do this? What is the benefit of going to pulse width
from their system of number of pulses per cycle?>
> 1) Add a signal diode (1N4148) in series with the signal from IC pin 6
> (i.e. cut the trace and hook it between the two points "B" on the
> schematic, cathode towards the transistor)
Bear with someone with no experience but at least a little interest in the
subject. That's a high speed switching diode, AFAICT, and used in series it
will pass current in only one direction . . .
> 2) Change the 2.2 k resistor to 12 k.
You would normally change a resistor value to change a time value in a
dependent RC circuit or to protect some other component from drawing too
much current, correct?
> 3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode of
> the diode to V-
>
> 4) Change the 330 ohm resistor to 2.2 k
OK, I'm lost although after I post this I will probably find out I was lost
far early in the process. I'll stop here even though I have some more
questions about your other modification suggestions because I'm a NOT a
professional engineer who has been doing things like this (or worse) for
well over forty years. I also know that my level of competence is NOT
sufficient for me to tackle it without lots and lots more discussion and
education.
I've already discovered that X-10 gear has naked 110VAC running all over the
circuit boards, making tinkering by noobs like me a lot more dicey than
trying to solder remote contacts to a coin cell powered keychain controller
circuit board. The only way that power source could hurt you is if you ate
it or someone shot it at you with a slingshot. More my kind of "futzing."
With the lamp module apart in my hands I have to really marvel at all the
engineering that went into them and how well that simple circuitry has
endured.
--
Bobby G.
Robert Green
news:134...@news1.IPSWITCHS.CMM...
I assume that means that his optoisolator drives the triac gate from the
powerline itself, and not modified in any way through the module's IC. I
also assume that by getting the triggering information from the powerline,
the unit is now, as I wanted in the first place, quite "blind" to dim or
brighten commands.
The author of the mod in question wrote:
| "When the zero-crossing circuit detects a zero crossing
| voltage and the LED is illuminated, the gate on the triac in the
| optoisolator is triggered with the same phase as the phase of the line
| voltage. This line phase current is then used as the gate trigger to the
| alternistor."
If I understand this correctly, it doesn't matter what the width of the
pulses coming out of the X-10 IC are. Nor does it matter how many small
pulse occur within each half cycle. When the ON signal arrives at the
module, current starts flowing because the current used to power the gate
circuit is activated. However, it no longer gets any information about the
bright or dim levels because the triac is "beating" to the ZC data that now
comes from the optoisolator/AC powerline instead and not the IC output. Is
that correct? I assume what turns the module off is an OFF command that
interrupts the output from the optoisolator so that there's no longer any
pulses being sent. I thought Isaac said there was always a pulse going to
the triac, even when the unit was off.
--
Bobby G.
Robert Green
news:134...@news1.IPSWITCHS.CMM...
But it also pretty clearly states that advanced soldering skills are
required. )-:
From reading more into that particular mod, I've gleaned that it's necessary
to feed the ZC timing to the triac in order to deal with the reversing
polarity of the AC signal. That wasn't something that was at first clear in
reading up about triacs. Obviously, electronics is not a real hobby of
mine. I am only in it this far to try to reclaim some usefulness out of a
carton full of WS-467 wallswitches and LM-465 lamp modules and because of a
general interest in how this stuff works.
I was hoping that the required mod would be a simple one, like the disabling
of local sense on some appliance modules. You just need to open the case
and snip the lead to a diode that, IIRC, is conveniently mounted vertically.
That I can handle. Piggy-backing chip sockets or adding additional
microprocessors is not within my skill set, even with my new Weller
soldering station. My work looks somewhat better, but it's still nothing I
would trust a 110VAC device with. Also, considering all of these came
basically free with Ebay X-10 lots I bought for the other components in the
lot. Many of them came nearly free with the infamous "X-10 free vouchers"
combo packs. It would probably just be easier to sell them all than butcher
them. My box of X-10 patients that didn't survive various complex mods is
impressive. )-:
From what I had read here and elsewhere, it sounded very much like triacs
were solid state switches that could pass large amounts of current via the
input of very much small current. They also appear to be able to switch
incredibly quickly compared to mechanical switches. But a practical
application like this makes the theory easier to understand. When I read
that they were bidirectional, I thought it meant passing AC freely, but it's
a lot more complex than that.
--
Bobby G.
Robert Green
> The delay of that pulse with respect to powerline zero crossings determine
> the brightness. It is not clear how they adjust the phase, but it is
probably
> done by some sort of timer in the IC whose count for each half cycle is a
> function of the dim level.
If the line driving the triac is not pulsed in any way, but is constantly
powered, I thought that the output of the triac will always be 100% but
obviously it's more complex than that. Not only is the light output chopped
each A/C cycle, but it seems that from Isaac said that they number of pulse
occurring during each A/C cycle is chopped into smaller pulses. More
pulses, more light. Might that be to keep the triac cooler than it would be
with longer pulses? Why would they do it that way instead of a variable
width pulse that lengthed as the brightness was turned up?
I've been reading about triacs all night and it says at Wiki: "Triac is one
of many power-enhancing Mini-Cons who help the Autobots search the galaxy
for pure energon ore." No, wait, that's: "It should be noted that once
avalanche breakdown has occurred, the thyristor continues to conduct,
irrespective of the gate voltage, until either: (a) the potential VG is
removed or (b) the current through the device (anode-cathode) is less than
the holding current specified by the manufacturer.
So it seems that even keeping the gate high all the time wouldn't work It
seems that one of the mods extracted the ZC via an optoisolator and that
implies that the triac has to be pulsed in phase with the AC cycle for it to
allow current to pass. That's not how I thought of a triac, conceptually.
When the author warns "this circuit only works if line current is fed into
pin 6 of the optoisolator. If you hook the circuit up wrong, the
zero-crossing circuit will not detect the voltage zero crossing and will not
trigger the alternistor" it seems to imply that to pass A/C current, the
triac must be synched to deal with the constantly reversing polarity of the
AC current.
--
Bobby G.
Robert Green
news:134...@news1.IPSWITCHS.CMM...
> If you actually have lamp modules that respond to all lights
> off (none of mine do) it won't affect that either.
I was so perplexed by this I went looking for the powerflash module's
instructions and this fault is indeed described (sort of as a benefit) and
explained why I remembered lamp module lights flashing and ending up off.
Those were all set to the alarm's own unit code so they would turn off, but
none of the 15 other unit codes would.
What's the difference? A blip in the PIC? The wall switches obey ALL
LIGHTS OFF; why not the lamp modules? I thought they shared the same
circuit design?
<<In Mode 1 the Burglar Alarm Interface will turn ON ALL lamp modules and
wall switch modules set to its Housecode and will also turn ON any other
modules set to its Unit Code, a stereo connected to an appliance module for
example. All lamp modules and wall switch modules are left in the ON state
when the alarm is de-activated but the modules set to the same Unit Code as
the Burglar Alarm Interface will be turned OFF.
In Mode 2 the Burglar Alarm Interface will FLASH all lights connected to
lamp modules or wall switch modules. All lamp and wall switch modules will
be left in the ON state when the alarm is de-activated but appliance modules
set to the same Housecode as the Burglar Alarm Interface will be turned OFF.
In Mode 3 the Burglar Alarm Interface will turn ON all modules set to the
same Housecode and Unit Code as the interface. All modules set to the same
Housecode and Unit Code as the Burglar Alarm Interface will be turned OFF
when the alarm is de-activated. Mode 3 is the same as mode 1 except that the
interface does not send the All Lights On code to turn on ALL lamp modules
and wall switch modules set to the same Housecode as the interface. >>
The worst part about it is that I am sure you've told me this before.
Probably more than once. I plead Mad Cow.
--
Bobby G.
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
> "Jeff Volp" <Jeff...@msn.com> wrote in message
> news:08F1k.18467$102....@bgtnsc05-news.ops.worldnet.att.net...
> > The delay of that pulse with respect to powerline zero crossings determine
> > the brightness. It is not clear how they adjust the phase, but it is
> probably
> > done by some sort of timer in the IC whose count for each half cycle is a
> > function of the dim level.
>
> If the line driving the triac is not pulsed in any way, but is constantly
> powered, I thought that the output of the triac will always be 100% but
> obviously it's more complex than that.
No; you are correct.
Absent a drive signal to the gate, a triac does not conduct at all. When
a gate signal is applied, and if there is a voltage across the triac, it
will turn on (start to conduct). Once it is conducting, the gate can no
longer control it (it can not be turned off by the gate). At the next
zero crossing, the triac will stop conducting until a signal is applied
to the gate again. There are other weird conditions that can make the
thing turn on, but they don't affect this discussion.
So, by delaying the gate signal with respect to the zero crossings, the
triac can be turned on for any desired percentage of time.
> Not only is the light output chopped
> each A/C cycle, but it seems that from Isaac said that they number of pulse
> occurring during each A/C cycle is chopped into smaller pulses. More
> pulses, more light.
No. The "earliest" pulse gates the triac; the others don't do anything.
I don't know why the others are there. Maybe it's just an artifact of
how the chip does phase control.
> Might that be to keep the triac cooler than it would be
> with longer pulses?
Triacs "keep cool" automatically, because of the way they work. When
off, there is no current flowing, so no heat. When on, there's very
little voltage drop across them (less than a fully saturated transistor)
and so again, very little energy is turned into heat. The only time they
show much dissipation is during the time they are switching from off to
on, and they are designed to make that happen as fast as possible --
which is precisely why they generate electrical noise.
> Why would they do it that way instead of a variable
> width pulse that lengthed as the brightness was turned up?
That would work; as I said, I don't know why the X-10 unit uses a string
of pulses. Most inexpensive "lamp dimmers" use a very simple circuit
that drive the triac with a varying width pulse. In higher power
circuits, it's important to get the device turned on as fast as
possible, and doing that requires a very fast, high-power drive signal
which, if it were applied all the time, would destroy the gate. Usually
that is provided by a single very short but high-energy pulse.
> I've been reading about triacs all night and it says at Wiki: "Triac is one
> of many power-enhancing Mini-Cons who help the Autobots search the galaxy
> for pure energon ore." No, wait, that's: "It should be noted that once
> avalanche breakdown has occurred, the thyristor continues to conduct,
> irrespective of the gate voltage, until either: (a) the potential VG is
> removed or (b) the current through the device (anode-cathode) is less than
> the holding current specified by the manufacturer.
>
> So it seems that even keeping the gate high all the time wouldn't work
That would cause it to turn on shortly after each zero crossing, and
stay on until the next. If what you want is a silent on-off switch (like
a relay), that works just fine.
> It
> seems that one of the mods extracted the ZC via an optoisolator and that
> implies that the triac has to be pulsed in phase with the AC cycle for it to
> allow current to pass.
It does need to be synched to the AC phase, but not "to allow current to
pass", but rather to vary the percentage of time the current is passing;
if you pulse that gate, say, at each voltage peak, the triac will
deliver power for the second half of each half cycle. Remember, it turns
itself off at every zero crossing.
> That's not how I thought of a triac, conceptually.
> When the author warns "this circuit only works if line current is fed into
> pin 6 of the optoisolator. If you hook the circuit up wrong, the
> zero-crossing circuit will not detect the voltage zero crossing and will not
> trigger the alternistor" it seems to imply that to pass A/C current, the
> triac must be synched to deal with the constantly reversing polarity of the
> AC current.
Triacs will conduct for both polarities of the AC signal; their cousins
in the thyristor family, SCRs (Silicon Controlled Rectifier), will only
conduct for one polarity, and then only when a gate signal is applied.
Because of the way they are built, SCRs can handle hugely greater
currents than triacs (thousands of amperes or more). When it's necessary
to control that sort of power, two SCRs are connected back-to-back, and
the gates are driven alternately, on alternate half cycles.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
That is correct.
> When the ON signal arrives at the
> module, current starts flowing because the current used to power the gate
> circuit is activated.
As successive "brighten" commands are sent, the leading edge of the
first pulse moves to occur earlier in the half cycle, so the triac is
turned on for progressively greater percentages of time -- and the lamp
grows brighter.
> However, it no longer gets any information about the
> bright or dim levels because the triac is "beating" to the ZC data that now
> comes from the optoisolator/AC powerline instead and not the IC output. Is
> that correct?
X-10 commands are sent right at zero crossings, so the triacs in all the
modules are "off".
> I assume what turns the module off is an OFF command that
> interrupts the output from the optoisolator so that there's no longer any
> pulses being sent. I thought Isaac said there was always a pulse going to
> the triac, even when the unit was off.
I did. But that pulse occurs so late in the half cycle that essentially
no energy gets to the lamp -- just a tiny "blip".
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
--snippety-snip--
> From what I had read here and elsewhere, it sounded very much like triacs
> were solid state switches that could pass large amounts of current via the
> input of very much small current.
That is precisely why they are so useful.
> They also appear to be able to switch
> incredibly quickly compared to mechanical switches.
Sort of; they can turn on very rapidly, but getting them off again can
be a bit tricky.
> But a practical
> application like this makes the theory easier to understand. When I read
> that they were bidirectional, I thought it meant passing AC freely, but it's
> a lot more complex than that.
They pass AC freely, in both directions, from when a trigger pulse
arrives until the next zero crossing.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
> "isw" <i...@witzend.com> wrote in message
> news:isw-A19801.2...@newsgroups.comcast.net...
> > In article <08F1k.18467$102....@bgtnsc05-news.ops.worldnet.att.net>,
> > "Jeff Volp" <Jeff...@msn.com> wrote:
> >
> > > IC pin 8 is the output that drives the triac. The delay of that pulse
> with
> > > respect to powerline zero crossings determine the brightness.
> >
> > Actually, I think it's pin 6 that drives the triac, via C337 (assuming
> > that schematic is correct).
> >
> >
> > A while back, I hacked around in those controllers. Here are some of my
> > notes:
> >
> > "The IC generates a series of pulses, with at least one always present,
> > near but before the zero-crossing (i.e. even at "off" the triac is
> > triggered, just very late in the half-cycle).
> >
> > "As the "brighten" signal is sent, the pulse first slides earlier in the
> > half-cycle, and then multiple pulses appear, with more and more as full
> > on is approached."
>
> Does that mean that the pulse width does not vary, but that the level of the
> light is determined by how many pulses of a fixed width are received during
> an AC cycle?
The level of light is determined by when the leading edge of the
earliest pulse arrives. The other pulses have no effect.
> I assume that would me they are obviously much shorter in
> duration than 1/2 the AC cycle. It sounds like they are "rechopping" the
> pulse into smaller pulses and that they aggregate to give the desired end
> level. I am not explaining that well, I fear. It seems like there are two
> pulse aggregations, a wheel within a wheel Ixion sort of thing.
The fact that there is a train of pulses is probably an artifact of the
way the IC in the X-10 unit accomplishes phase delay (to retard the
timing of the gate drive).
> > What I wanted was a single duration-modulated pulse (wider for brighter,
> > of course), and here's how I got it:
>
> Why did you want to do this? What is the benefit of going to pulse width
> from their system of number of pulses per cycle?>
I was interested in using X-10 units to remotely control stuff other
than lamps and coffee pots. Getting an optically isolated variable width
pulse was a good starting place. I was not going to use that signal to
drive a triac in amy way.
> > 1) Add a signal diode (1N4148) in series with the signal from IC pin 6
> > (i.e. cut the trace and hook it between the two points "B" on the
> > schematic, cathode towards the transistor)
>
> Bear with someone with no experience but at least a little interest in the
> subject. That's a high speed switching diode, AFAICT, and used in series it
> will pass current in only one direction . . .
Yup. It allows the pulses from the IC to pass into a capacitor (for
filtering them to an average DC level), while preventing the internals
of the IC from (possibly) drawing a current that would prevent taht
filtering from taking place.
> > 2) Change the 2.2 k resistor to 12 k.
>
> You would normally change a resistor value to change a time value in a
> dependent RC circuit or to protect some other component from drawing too
> much current, correct?
Yup. In this case, I raised the value to allow a smaller capacitor to be
used to get the time constant I wanted.
> > 3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode of
> > the diode to V-
That's the cap that integrates the pulse train into a DC value
> > 4) Change the 330 ohm resistor to 2.2 k
Simplistically, the 12K resistor determines how fast the cap charges
(but not discharges, because the diode prevents that), while the 2.2K
controls the discharge time.
--snip--
> I've already discovered that X-10 gear has naked 110VAC running all over the
> circuit boards, making tinkering by noobs like me a lot more dicey than
> trying to solder remote contacts to a coin cell powered keychain controller
> circuit board.
True, but if you're careful to make sure it's not plugged in while you
have your fingers in it, there's not much to worry about. There are no
components in there that can store large chunks of energy, for example.
Keep on hacking; that's the way to get better and more confident at it.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
> "Jeff Volp" <Jeff...@msn.com> wrote in message
> news:upJ1k.19034$102...@bgtnsc05-news.ops.worldnet.att.net...
> > "Robert Green" <ROBERT_G...@YAH00.COM> wrote in message
> > news:hOWdnZPUEpdFotrV...@rcn.net...
> >
> > > I believe the first test will just be to simply disconnect pin 8 from
> the
> > > control line. Hopefully it will be easy to rebridge if that turns out
> not
> > > to work. Also, hopefully, it won't incinerate itself after snipping
> that
> > > line. I guess I can trot out the old 20mm ammo box I have for
> containment
> > > of explosive experiments - well, maybe just leave it on a fireproof
> > > surface
> > > to test . . .
> >
> > Whoops, that was a typo before. Pin 8 is used for the local control.
> > Snipping that will only disable local control. Pin 6 drives the triac.
> > That line is essential. If snipped there will be no on/off control at
> all.
> > The dimming phase control is inside the IC.
>
> As I understand it now, the pulse to the triac has to occur twice every
> cycle and has to be alternatingly negative and positive to allow each half
> of the AC cycle to pass.
The pulses do not have to alternate in polarity; that's one of the neat
things about triacs.
> The dimmer does its magic by narrowing the width
> of that pulse - shorter means less power gets to the device and its dimmer.
> As I said to Dan, I thought a triac was just a very fast solid state relay.
>
> > It might be possible to extend the pulse coming out of the IC so that if
> > there is ANY pulse at all, the transistor will remain on through the
> > beginning of the next cycle so the unit will switch on right after the
> zero
> > crossing.
>
> It sounds like the mod that uses the alternistor and the optoisolator does
> just that. It seems that the optoisolator extracts the ZC data and then the
> additional circuitry creates its own full width pulse independent of
> whatever length pulse comes out of the IC.
It sounds like you're attributing too much functionality to the
optoisolator; it doesn't *extract* anything. It's just a transistor that
turns on when light shines on it. And the light is the LED that's inside
it. The output of the opto just repeats whatever is on its input while
isolating the possibly dangerous voltage levels on the input side.
> So if the module was dimming the
> output, it wouldn't matter because that pulse is driving a latching circuit
> that stays on until the next ZC, correct?
I don't quite follow you, but I don't think that's right.
The gate pulse (optically isolated or not) turns the triac on; the next
following zero crossing allows it to turn off. The "latching" part is
provided by the triac itself, because it's not necessary to continue
applying the gate signal after it's turned on.
Isaac
Dan Lanciani
| You're correct. At first glance I thought he was talking about putting a
| solid state relay inside an appliance module to eliminate the clack. After
| your comment, I went and tested the modules I have and while the wall
| switches respond to All Lights ON/OFF, the lamp modules don't. They only
| respond to All Lights ON.
Although All Lights Off was part of the original command set it was not
implemented by X10 until pretty late in the game. I don't think most of
my cheap wall switches respond to it either. The relay wall switches have
responded to it for a long time, though; possibly since their introduction.
| Bummer. Well, that makes the project somewhat
| less attractive. At least the All Lights ON command is more useful to me
| than All Lights Off would be. How is that the X-10 security system flashes
| the house lights?
It alternates All Lights On with All Units Off.
| My whole premise
| was based on a misunderstanding of how triacs work. I thought they were
| merely high speed electronic relays.
They are to a first approximation, but there are a lot of details that
can trip you up.
| It's become apparent that the triac can only do its magic when synched to
| the zero crossing.
You can turn a triac on any time, but unless you are dimming it is usually
best to turn it on near a zero crossing. You can't turn it off unless
there is no current flowing.
| Perhaps you could be kind enough to explain what would happen if the line to
| the triac gate was high all the time. Would it conduct only on the first
| half cycle, or not at all or would the magic smoke escape? (-:
Having the gate "high" is probably not the best way to think of it. A
triac is triggered by current flowing between gate and MT1. There are
two possible directions for that current and two possible polarities for
the voltage between MT1 and MT2. Together this gives you four combinations
which are commonly referred to as quadrants of operation. (If you google
the terms you will find pictures.) Most garden variety triacs can be
triggered in any quadrant; however, it may require more current to trigger
in some quadrants than in others. Some triacs are designed to be triggerable
in only three of the four quadrants to reduce certain kinds of false
retriggering. There may be more exotic variations.
Note that the requirement for the trigger current to flow between gate and
MT1 is independent of the quadrants. I've read claims that some triacs
are symmetrical with respect to MT1 and MT2 but I wouldn't want to count
on it.
So, assuming you have satisfied the triggering polarity requirements (if
any) and you drive current between the gate and MT1 all the time, the
triac will conduct all the time.
Dan Lanciani
ddl@danlan.*com
Dan Lanciani
| In article <hpqdncmhFKn1b9XV...@rcn.net>,
| "Robert Green" <ROBERT_G...@YAH00.COM> wrote:
| > As I understand it now, the pulse to the triac has to occur twice every
| > cycle and has to be alternatingly negative and positive to allow each half
| > of the AC cycle to pass.
|
| The pulses do not have to alternate in polarity; that's one of the neat
| things about triacs.
Though it is possible that you might want them to alternate to stay in
the optimal triggering quadrants.
| > It sounds like the mod that uses the alternistor and the optoisolator does
| > just that. It seems that the optoisolator extracts the ZC data and then the
| > additional circuitry creates its own full width pulse independent of
| > whatever length pulse comes out of the IC.
|
| It sounds like you're attributing too much functionality to the
| optoisolator; it doesn't *extract* anything. It's just a transistor that
| turns on when light shines on it. And the light is the LED that's inside
| it. The output of the opto just repeats whatever is on its input while
| isolating the possibly dangerous voltage levels on the input side.
The MOC3042 used in the modification is more than a simple optoisolator;
it includes its own zero-crossing detector. The internal triac is fired
near the next zero crossing if the LED is on, i.e., if there is input drive.
This is convenient since the main triac will also fire near the zero crossing
independent of when the integrated drive signal reaches the activation
threshold.
Dan Lanciani
ddl@danlan.*com
isw
ddl@danlan.*com (Dan Lanciani) wrote:
> In article <isw-3AB4BB.1...@newsgroups.comcast.net>,
> i...@witzend.com (isw) writes:
> | In article <hpqdncmhFKn1b9XV...@rcn.net>,
> | "Robert Green" <ROBERT_G...@YAH00.COM> wrote:
>
> | > As I understand it now, the pulse to the triac has to occur twice every
> | > cycle and has to be alternatingly negative and positive to allow each
> | > half
> | > of the AC cycle to pass.
> |
> | The pulses do not have to alternate in polarity; that's one of the neat
> | things about triacs.
>
> Though it is possible that you might want them to alternate to stay in
> the optimal triggering quadrants.
The triggering sensitivity is different, but the triac can always be
triggered.
> | > It sounds like the mod that uses the alternistor and the optoisolator
> | > does
> | > just that. It seems that the optoisolator extracts the ZC data and then
> | > the
> | > additional circuitry creates its own full width pulse independent of
> | > whatever length pulse comes out of the IC.
> |
> | It sounds like you're attributing too much functionality to the
> | optoisolator; it doesn't *extract* anything. It's just a transistor that
> | turns on when light shines on it. And the light is the LED that's inside
> | it. The output of the opto just repeats whatever is on its input while
> | isolating the possibly dangerous voltage levels on the input side.
>
> The MOC3042 used in the modification is more than a simple optoisolator;
Yes, it is. I was not aware that was the device being used. Since the
output of the X-10 unit's IC is already phase synchronized, it's not
clear why something like that is necessary though.
Isaac
Robert Green
news:134...@news1.IPSWITCHS.CMM...
ROBERT_G...@YAH00.COM (Robert Green) writes:
>
> | You're correct. At first glance I thought he was talking about putting
a
> | solid state relay inside an appliance module to eliminate the clack.
After
> | your comment, I went and tested the modules I have and while the wall
> | switches respond to All Lights ON/OFF, the lamp modules don't. They
only
> | respond to All Lights ON.
>
> Although All Lights Off was part of the original command set it was not
> implemented by X10 until pretty late in the game. I don't think most of
> my cheap wall switches respond to it either. The relay wall switches have
> responded to it for a long time, though; possibly since their
introduction.
It's a mix here. When I get a moment I'll try to figure out which lights do
and which do not. What's clear is a lot more units go on than go off when
using the All Lights On and Off commands.
> | Bummer. Well, that makes the project somewhat
> | less attractive. At least the All Lights ON command is more useful to
me
> | than All Lights Off would be. How is that the X-10 security system
flashes
> | the house lights?
>
> It alternates All Lights On with All Units Off.
> | My whole premise
> | was based on a misunderstanding of how triacs work. I thought they were
> | merely high speed electronic relays.
>
> They are to a first approximation, but there are a lot of details that
> can trip you up.
Indeed. I'm tripping all over the place.
> | It's become apparent that the triac can only do its magic when synched
to
> | the zero crossing.
>
> You can turn a triac on any time, but unless you are dimming it is usually
> best to turn it on near a zero crossing. You can't turn it off unless
> there is no current flowing.
OK - that's a point I was missing and why I thought they had to be synched
to the ZC.
> | Perhaps you could be kind enough to explain what would happen if the
line to
> | the triac gate was high all the time. Would it conduct only on the
first
> | half cycle, or not at all or would the magic smoke escape? (-:
>
> Having the gate "high" is probably not the best way to think of it. A
> triac is triggered by current flowing between gate and MT1. There are
> two possible directions for that current and two possible polarities for
> the voltage between MT1 and MT2. Together this gives you four
combinations
> which are commonly referred to as quadrants of operation. (If you google
> the terms you will find pictures.) Most garden variety triacs can be
> triggered in any quadrant; however, it may require more current to trigger
> in some quadrants than in others. Some triacs are designed to be
triggerable
> in only three of the four quadrants to reduce certain kinds of false
> retriggering. There may be more exotic variations.
I'm having a hard enough time with the garden variety triac.
> Note that the requirement for the trigger current to flow between gate and
> MT1 is independent of the quadrants. I've read claims that some triacs
> are symmetrical with respect to MT1 and MT2 but I wouldn't want to count
> on it.
>
> So, assuming you have satisfied the triggering polarity requirements (if
> any) and you drive current between the gate and MT1 all the time, the
> triac will conduct all the time.
I am still a bit confused about one thing. When the AC waveform crosses
over, does current through the device drop to zero and the triac stops
conducting simply because there's no current at that point on the sine wave?
Does the triac have to be "retriggered" at that point and after each
subsequent recrossing or does it start firing again as soon as current
begins to flow again in the opposite direction?
I have another question. When taking apart the lamp module, I noticed that
the tiny triac has an enormous aluminum heat sink. What process generates
the high heat developed? I know it can get pretty hot from someone
accidentally plugging a 1400W hairdryer into one. It ran the hairdryer,
even as the case melted around all the components. )=:
FWIW, there's an interesting looking three wheeled car called the Triac:
http://www.inhabitat.com/2008/05/20/transportation-tuesday-the-80mph-triac-g
oes-on-sale/
"The TRIAC is essentially a large, covered trike. The 20kw electric motor
can achieve a very reasonable 80mph, and will take you on travels up to 100
miles on any given charge. It takes about 6 hours for its lithium-ion
battery to recharge fully and, as with most electric vehicles, it comes with
a regenerative braking system. The package for all of this three-wheeled fun
runs about $20,000 dollars."
And the even more interesting stackable car from MIT:
--
Bobby G.
Robert Green
. . . And the even more interesting stackable car from MIT:
http://www.inhabitat.com/2007/11/13/transportation-tuesday-mits-stackable-ci
ty-car/
And this interesting tidbit:
"Why does a gas lantern use a silk mantle? How does it produce such intense
light -- BW, Santa Clara, CA
The mantle of a lantern is actually a ceramic ash. The silk itself burns
away completely and leaves behind only of the oxides of materials that were
incorporated in the silk mantle when it was manufactured. The principal
oxide formed when the standard Welsbach mantle is burned is thorium oxide,
with a few percent of cerium oxide and other oxides. This use of thorium
oxide or thoria, is a rare example of a radioactive element (thorium is
radioactive) permitted in common household use. Thoria glows brightly when
heated because it can tolerate extremely high temperatures without melting
and because it is a very effective emitter of thermal radiation at
temperatures of roughly 2200° C."
But wait, there's more (don't you just love research on the net - you always
learn at least three more things than the thing you were looking for. I
found this interesting because I know we've had reports like this here.
Subject: What does it mean when the lights brighten when a motor starts?
This usually means that the neutral wire in the panel is
loose. Depending on the load balance, one hot wire may end up
being more than 110V, and the other less than 110V, with
respect to ground. This is a very hazardous situation - it can
destroy your electronic equipment, possibly start fires, and in
some situations electrocute you (ie: some US jurisdictions
require the stove frame connected to neutral).
If this happens, contact your electrical authority immediately
and have them come and check out the problem. If you say "loose
neutral", they will come.
Note: a brief (< 1 second) brightening is sometimes normal with
lighting and motors on the same 220V with neutral circuit. A
loose main panel neutral will usually show increased brightness
far longer than one second. In case of doubt, get help.
OK. Enough electrivia. Back to reading up on triacs.
--
Bobby G.
Robert Green
Are you saying they could have taken the IC output and processed it so that
as soon as a pulse was detected, the triac would be gated on until the next
ZC? I'm not sure I follow . . .
--
Bobby G.
Robert Green
<stuff snipped>
> > As I understand it now, the pulse to the triac has to occur twice every
> > cycle and has to be alternatingly negative and positive to allow each
half
> > of the AC cycle to pass.
>
> The pulses do not have to alternate in polarity; that's one of the neat
> things about triacs.
As I looked at the mod schematic, I realized that the switching was
occurring without any polarity reversal of the trigger. I am assuming that
the pulse has to be given after each ZC because the triac has turned itself
off because of a lack of current flow. It's probably a bad analogy but it
reminds me of the timing of spark plugs in cars to coincide with top dead
center. If the spark comes too late or too early, bad things happen.
> > The dimmer does its magic by narrowing the width
> > of that pulse - shorter means less power gets to the device and its
dimmer.
> > As I said to Dan, I thought a triac was just a very fast solid state
relay.
> >
> > > It might be possible to extend the pulse coming out of the IC so that
if
> > > there is ANY pulse at all, the transistor will remain on through the
> > > beginning of the next cycle so the unit will switch on right after the
> > > zero crossing.
> >
> > It sounds like the mod that uses the alternistor and the optoisolator
does
> > just that. It seems that the optoisolator extracts the ZC data and then
the
> > additional circuitry creates its own full width pulse independent of
> > whatever length pulse comes out of the IC.
>
> It sounds like you're attributing too much functionality to the
> optoisolator; it doesn't *extract* anything. It's just a transistor that
> turns on when light shines on it. And the light is the LED that's inside
> it. The output of the opto just repeats whatever is on its input while
> isolating the possibly dangerous voltage levels on the input side.
I worded that badly. I should have said that the support circuitry in the
mod detects the ZC and then feeds that to the optoisolator which then pulses
the triac with power that is independent of the existing module circuitry.
I assume that's done because of the line voltages involved and to prevent
any unintended interaction of the modification circuitry with the module's
circuits.
> > So if the module was dimming the
> > output, it wouldn't matter because that pulse is driving a latching
circuit
> > that stays on until the next ZC, correct?
>
> I don't quite follow you, but I don't think that's right.
What I was trying to say is that the no matter what the length, duration and
frequency of pulses the X-10 IC generates, and no matter where they occur on
the sine wave, the triac will now conduct full time because the gate signal
no longer comes the IC but from the AC line via the optoisolator.
Jeff, if you're reading this, it sounds a lot like Schelte's debugging trick
of feeding the ZC information from the TW-7223(?) and data information from
the XTB.
> The gate pulse (optically isolated or not) turns the triac on; the next
> following zero crossing allows it to turn off. The "latching" part is
> provided by the triac itself, because it's not necessary to continue
> applying the gate signal after it's turned on.
OK. That explains what I thought was happening elsewhere in the support
circuitry. Is it correct to say the triac just goes off when the ZC is
reached (because no current flows at that point in an AC waveform) and then
the gate pulse turns it back on again for another cycle?
(Thanks for taking the time to explain this stuff. Hopefully, it will also
be helpful to others. I was a little hesitant to even discuss triacs since
the great "Triac Thread War" of a while back!)
--
Bobby G.
Robert Green
<stuff snipped>
I just wanted to prove I was paying attention. (-: I that I at least have
a little sense of what turns the triac on and off and how dimming is
accomplished. I have to confess that I am still a little hazy on how the
module itself turns on and off and just how the sequence of events occurs
from button push to lamp lighting.
--
Bobby G.
Robert Green
<stuff snipped>
> > > A while back, I hacked around in those controllers. Here are some of
my
> > > notes:
> > >
> > > "The IC generates a series of pulses, with at least one always
present,
> > > near but before the zero-crossing (i.e. even at "off" the triac is
> > > triggered, just very late in the half-cycle).
> > >
> > > "As the "brighten" signal is sent, the pulse first slides earlier in
the
> > > half-cycle, and then multiple pulses appear, with more and more as
full
> > > on is approached."
> >
> > Does that mean that the pulse width does not vary, but that the level of
the
> > light is determined by how many pulses of a fixed width are received
during
> > an AC cycle?
>
> The level of light is determined by when the leading edge of the
> earliest pulse arrives. The other pulses have no effect.
Would another way to say that be the light level is determined by the point
on the sine wave where the gate pulse arrives and that that unit stays on
until the end of the cycle, no matter what happens afterward in that cycle?
So it's not possible to have a sine wave that has four "bands" of on/off
pulses? Or is it just that way for the X-10 modules? I thought, when you
talked about pulses, that each one of them turned on the triac for a tiny
bit of time, and that all of them added together in each cycle increased the
power output. That would require switch the triac on and off multiple times
within the cycle. That description is true of how all the chopped A/C
cycles add up, but I think you're saying the pulses that follow are not
having any effect on the state of the triac.
After reading more, what I envision now from your description is a sliding
window sort of thing where the amount of current flowing depends on how far
you slide the ON window to the left-most window stop, which in this case, is
the zero crossing. That sound anywhere near right?
> > I assume that would me they are obviously much shorter in
> > duration than 1/2 the AC cycle. It sounds like they are "rechopping"
the
> > pulse into smaller pulses and that they aggregate to give the desired
end
> > level. I am not explaining that well, I fear. It seems like there are
two
> > pulse aggregations, a wheel within a wheel Ixion sort of thing.
>
> The fact that there is a train of pulses is probably an artifact of the
> way the IC in the X-10 unit accomplishes phase delay (to retard the
> timing of the gate drive).
So it might even be possible it's really just noise with no particular
function but no particular harm to the operation of the module. I assume
you detected it with some sort of logic analyzer?
> > > What I wanted was a single duration-modulated pulse (wider for
brighter,
> > > of course), and here's how I got it:
> >
> > Why did you want to do this? What is the benefit of going to pulse
width
> > from their system of number of pulses per cycle?>
>
> I was interested in using X-10 units to remotely control stuff other
> than lamps and coffee pots. Getting an optically isolated variable width
> pulse was a good starting place. I was not going to use that signal to
> drive a triac in amy way.
Sounds interesting. Wouldn't such an extension give you trouble with
standard repeaters?
> > > 1) Add a signal diode (1N4148) in series with the signal from IC pin 6
> > > (i.e. cut the trace and hook it between the two points "B" on the
> > > schematic, cathode towards the transistor)
> >
> > Bear with someone with no experience but at least a little interest in
the
> > subject. That's a high speed switching diode, AFAICT, and used in
series it
> > will pass current in only one direction . . .
>
> Yup. It allows the pulses from the IC to pass into a capacitor (for
> filtering them to an average DC level), while preventing the internals
> of the IC from (possibly) drawing a current that would prevent taht
> filtering from taking place.
So with the capacitor, the signal is being smoothed out from a pulse train
to voltage level. Usenet II is going to need a whiteboard. At least ten
times now I've wanted to show something with a simple sketch. What does
that pulse train look like? Is it a square wave with the lowermost part at
0 volts and the uppermost part at Vcc+ (not sure if that the right term).
Would the resulting DC level be Vcc+/2 or something close to that?
> > > 2) Change the 2.2 k resistor to 12 k.
> >
> > You would normally change a resistor value to change a time value in a
> > dependent RC circuit or to protect some other component from drawing too
> > much current, correct?
>
> Yup. In this case, I raised the value to allow a smaller capacitor to be
> used to get the time constant I wanted.
At least I remember that much from reading my 555 cookbook 20+ years ago.
> > > 3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode of
> > > the diode to V-
>
> That's the cap that integrates the pulse train into a DC value
You said "average DC level" before. Is it safe to assume that DC value is
still going to show some trace of the underlying pulses because of how it
has been generated? Is that called ripple or is that something else
entirely?
> > > 4) Change the 330 ohm resistor to 2.2 k
>
> Simplistically, the 12K resistor determines how fast the cap charges
> (but not discharges, because the diode prevents that), while the 2.2K
> controls the discharge time.
Is that capacitor discharging during the time the pulse is at zero, thus
providing current in the circuit where there would have been none without
it?
> --snip--
>
> > I've already discovered that X-10 gear has naked 110VAC running all over
the
> > circuit boards, making tinkering by noobs like me a lot more dicey than
> > trying to solder remote contacts to a coin cell powered keychain
controller
> > circuit board.
>
> True, but if you're careful to make sure it's not plugged in while you
> have your fingers in it, there's not much to worry about. There are no
> components in there that can store large chunks of energy, for example.
I learned that lesson with an 555 design that reversed an agitator motor by
charging up a fairly large capacitor. They bite.
> Keep on hacking; that's the way to get better and more confident at it.
Thanks for the encouragement and the input. I feel a little like I felt on
the first day of kindergarten when I saw all the sixth graders writing in
cursive, reading big books and most impressive of all, taking the stairs two
at a time!
I suppose this means I'll have to finally break down and open an account at
Digikey or Mouser. (=;
--
Bobby G.
Marc_F_Hult
<ROBERT_G...@YAH00.COM> wrote in message
<rYadnVE6-IgY-tfV...@rcn.net>:
>Would another way to say that be the light level is determined by the
>point on the sine wave where the gate pulse arrives and that that unit
>stays on until the
>end of the cycle, no matter what happens afterward in that cycle?
^^^^^ ^^^^^
half-cycle half-cycle
>So it's not possible to have a sine wave that has four "bands" of on/off
>pulses?
Right. Only one per zero-crossing = two per complete cycle = one per
half-cycle..
>Or is it just that way for the X-10 modules?
This is true for all TRIAC-based dimming of AC.
>I thought, when you talked about pulses, that each one of them turned on
>the triac for a tiny bit of time, and that all of them added together in
>each cycle increased the power output. That would require switch the
>triac on and off multiple timeswithin the cycle. That description is
>true of how all the chopped A/C cycles add up, but I think you're saying
>the pulses that follow are not having any effect on the state of the
>triac.
Right. Dimming by TRIACs is called "phase-control" dimming for a reason.
One can characterize the amount of dimming by stating the number of
degrees after zero crossing ("phase") that the TRIAC goes into conduction.
The relationship between phase and light output is very non-linear and is
called the dimmer curve. Turning the TRIAC on as late as 20 degrees (out
of 180 degrees peer half cycle) still results in nearly 100% light
output, but less than 10% of fully on if delayed to 110 degrees.
I have constructed a spreadsheet of conduction ("phase") angle, turn-on
delay, resulting light intensity for typical incandescent lamp, RMS
voltage, and DMX-512 and 0-10vdc control signals that can be downloaded at
www.ECOntrol.org/dimmers/TRIACDimmerCalcs_MFHult.pdf
It also provides the relevant equations and graphs of conduction angle vs
light intensity and conduction angle vs RMS voltage.
HTH ... Marc
Marc_F_Hult
www.ECONtrol.org
Visit my Home Automation and Electronics Porch Sale at
www.ECOntrol.org/porchsale.htm
Dan Lanciani
| As I looked at the mod schematic, I realized that the switching was
| occurring without any polarity reversal of the trigger.
No, you were right the first time. The direction of the gate current is
reversing in step with the line, keeping the triggering in the more sensitive
quadrants. The unmodified module uses its own DC supply to drive the gate
current independent of the line polarity. Using the more sensitive quadrants
(or, in general, using two quadrants with the same sensitivity) keeps the
triggering times as symmetrical as possible minimizing the DC component in
the output.
| I am assuming that
| the pulse has to be given after each ZC because the triac has turned itself
| off because of a lack of current flow.
You assume correctly.
| I worded that badly. I should have said that the support circuitry in the
| mod detects the ZC and then feeds that to the optoisolator which then pulses
| the triac with power that is independent of the existing module circuitry.
Again, you were right the first time. This optoisolator has extra circuitry
to synchronize with the zero crossing. Although the output of the module's
IC is synchronized to the line, once it is integrated and passed through a
threshold detector there is no guarantee that the resulting transition will
be anywhere near a zero crossing of the supply. The MOC3042 insures that
the switching will happen only near the zero crossing. Note that we are
talking about the single transition from off to on when the module is so
commanded, not a transition that happens twice per cycle. Whether this
is important is up to you.
| I assume that's done because of the line voltages involved and to prevent
| any unintended interaction of the modification circuitry with the module's
| circuits.
I suspect you are correct. The zero crossing synchronization is just an
extra (but nice) feature that comes for free with a part that happens to
do just what is needed for the modification.
Dan Lanciani
ddl@danlan.*com
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
That's how it works without any processing. A pulse from the IC,
"amplified" by that transistor, drives the triac directly.
Adding a "standard" opto-isolator to drive an external (perhaps larger)
triac would not need any more synchronizing.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
It's the end of the next half-cycle (the next zero crossing), but
otherwise, yes; that's what happens.
> So it's not possible to have a sine wave that has four "bands" of on/off
> pulses? Or is it just that way for the X-10 modules? I thought, when you
> talked about pulses, that each one of them turned on the triac for a tiny
> bit of time, and that all of them added together in each cycle increased the
> power output. That would require switch the triac on and off multiple times
> within the cycle. That description is true of how all the chopped A/C
> cycles add up, but I think you're saying the pulses that follow are not
> having any effect on the state of the triac.
Correct; they do not. Once a triac is conducting, it's very difficult to
get it to turn off any way except removing the voltage across it
(actually, it's removing the current through it that makes it turn off).
> After reading more, what I envision now from your description is a sliding
> window sort of thing where the amount of current flowing depends on how far
> you slide the ON window to the left-most window stop, which in this case, is
> the zero crossing. That sound anywhere near right?
Right on. But think about how a half-sine looks -- a linear increase in
on-time does NOT result in a linear increase in power delivered to the
load.
>
> > > I assume that would me they are obviously much shorter in
> > > duration than 1/2 the AC cycle. It sounds like they are "rechopping"
> the
> > > pulse into smaller pulses and that they aggregate to give the desired
> end
> > > level. I am not explaining that well, I fear. It seems like there are
> two
> > > pulse aggregations, a wheel within a wheel Ixion sort of thing.
> >
> > The fact that there is a train of pulses is probably an artifact of the
> > way the IC in the X-10 unit accomplishes phase delay (to retard the
> > timing of the gate drive).
There is exactly one "on" interval per half cycle; if it is very short,
no appreciable power is delivered to the load. If it is nearly a full
half-cycle in duration, nearly full power is delivered.
> So it might even be possible it's really just noise with no particular
> function but no particular harm to the operation of the module.
It's not noise; it's a regular string of pulses.
> I assume you detected it with some sort of logic analyzer?
No; just an ordinary oscilloscope.
> > > > What I wanted was a single duration-modulated pulse (wider for
> brighter,
> > > > of course), and here's how I got it:
> > >
> > > Why did you want to do this? What is the benefit of going to pulse
> width
> > > from their system of number of pulses per cycle?>
> >
> > I was interested in using X-10 units to remotely control stuff other
> > than lamps and coffee pots. Getting an optically isolated variable width
> > pulse was a good starting place. I was not going to use that signal to
> > drive a triac in amy way.
>
> Sounds interesting. Wouldn't such an extension give you trouble with
> standard repeaters?
I didn't care about repeaters. What I wanted to do was control a large
number of electrical valves for an irrigation system. As I said, the
problem was that it was not repeatable -- the same number of "brighten"
pulses did not always result in the same pulse width, and so I could not
reliably select which irrigation circuit I wanted to run.
> > > > 1) Add a signal diode (1N4148) in series with the signal from IC pin 6
> > > > (i.e. cut the trace and hook it between the two points "B" on the
> > > > schematic, cathode towards the transistor)
> > >
> > > Bear with someone with no experience but at least a little interest in
> the
> > > subject. That's a high speed switching diode, AFAICT, and used in
> series it
> > > will pass current in only one direction . . .
> >
> > Yup. It allows the pulses from the IC to pass into a capacitor (for
> > filtering them to an average DC level), while preventing the internals
> > of the IC from (possibly) drawing a current that would prevent taht
> > filtering from taking place.
>
> So with the capacitor, the signal is being smoothed out from a pulse train
> to voltage level. Usenet II is going to need a whiteboard. At least ten
> times now I've wanted to show something with a simple sketch. What does
> that pulse train look like? Is it a square wave with the lowermost part at
> 0 volts and the uppermost part at Vcc+ (not sure if that the right term).
> Would the resulting DC level be Vcc+/2 or something close to that?
Honestly, I don't remember. I was doing this some years back. All I
recall is that starting from "full dim" there was one narrow, "square"
pulse, very close to the following zero-crossing. As "brighten" pulses
were sent, that pulse always moved earlier in the half-cycle, but as it
moved, it was joined by progressively more and more that looked just
like it. The "extra" pulses occurred later in the phase than the one
that turned the triac on, and so they had no effect on the operation of
the unit.
> > > > 2) Change the 2.2 k resistor to 12 k.
> > >
> > > You would normally change a resistor value to change a time value in a
> > > dependent RC circuit or to protect some other component from drawing too
> > > much current, correct?
> >
> > Yup. In this case, I raised the value to allow a smaller capacitor to be
> > used to get the time constant I wanted.
>
> At least I remember that much from reading my 555 cookbook 20+ years ago.
>
> > > > 3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode of
> > > > the diode to V-
> >
> > That's the cap that integrates the pulse train into a DC value
>
> You said "average DC level" before. Is it safe to assume that DC value is
> still going to show some trace of the underlying pulses because of how it
> has been generated? Is that called ripple or is that something else
> entirely?
Ripple would be a good term to use. The trade-off is that as you
increase the time constant to reduce the ripple, you also increase the
time the unit takes to respond to changes in the pulse width.
> > > > 4) Change the 330 ohm resistor to 2.2 k
> >
> > Simplistically, the 12K resistor determines how fast the cap charges
> > (but not discharges, because the diode prevents that), while the 2.2K
> > controls the discharge time.
>
> Is that capacitor discharging during the time the pulse is at zero, thus
> providing current in the circuit where there would have been none without
> it?
Yup.
> > > I've already discovered that X-10 gear has naked 110VAC running all over
> the
> > > circuit boards, making tinkering by noobs like me a lot more dicey than
> > > trying to solder remote contacts to a coin cell powered keychain
> controller
> > > circuit board.
> >
> > True, but if you're careful to make sure it's not plugged in while you
> > have your fingers in it, there's not much to worry about. There are no
> > components in there that can store large chunks of energy, for example.
>
> I learned that lesson with an 555 design that reversed an agitator motor by
> charging up a fairly large capacitor. They bite.
>
> > Keep on hacking; that's the way to get better and more confident at it.
>
> Thanks for the encouragement and the input. I feel a little like I felt on
> the first day of kindergarten when I saw all the sixth graders writing in
> cursive, reading big books and most impressive of all, taking the stairs two
> at a time!
>
> I suppose this means I'll have to finally break down and open an account at
> Digikey or Mouser. (=;
Learn how to take old gear apart and scavenge the parts. Not only do you
get all sorts of good stuff, but you improve your (un)soldering skills
at the same time.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
--snip--
> OK. That explains what I thought was happening elsewhere in the support
> circuitry. Is it correct to say the triac just goes off when the ZC is
> reached (because no current flows at that point in an AC waveform) and then
> the gate pulse turns it back on again for another cycle?
Precisely. Now, to complicate things a bit, there are loads for which
the zero-current point does not coincide with the zero-voltage point
(reactive loads like electric motors, for example). In that case, the
triac may not turn off at all. There are tricks to deal with that
circumstance.
> (Thanks for taking the time to explain this stuff. Hopefully, it will also
> be helpful to others. I was a little hesitant to even discuss triacs since
> the great "Triac Thread War" of a while back!)
My pleasure.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
--snip--
> I am still a bit confused about one thing. When the AC waveform crosses
> over, does current through the device drop to zero and the triac stops
> conducting simply because there's no current at that point on the sine wave?
Precisely.
> Does the triac have to be "retriggered" at that point and after each
> subsequent recrossing or does it start firing again as soon as current
> begins to flow again in the opposite direction?
It will not conduct again until the proper amount of gate current is
applied, while there is a voltage across the device.
> I have another question. When taking apart the lamp module, I noticed that
> the tiny triac has an enormous aluminum heat sink. What process generates
> the high heat developed?
Mostly, it's the voltage drop across the chunk of silicon that forms the
triac, although some of it may be due to the tiny wires that connect the
chip to the external leads.
A transistor is a three-layer device (NPN, say); a SCR is a four-layer
device (NPNP), and a triac comprises five (NPNPN or the other way
around). Interestingly, because of the way thyristors work, even though
they have more layers than transistors, the voltage drop across one when
conducting is lower.
But still, whatever that drop is, multiplied by RMS current that is
flowing, creates heat.
If you think about it, the worst case is when the device is "half on",
because the voltage drop is much larger. One reason to use a triac or
SCR instead of a transistor is because they sort of "automatically" go
through that halfway state very rapidly. Another is that the voltage
drop when conducting is lower.
Isaac
Andrew Gabriel
"Robert Green" <ROBERT_G...@YAH00.COM> writes:
> Oops - sorry for the truncation:
>
> . . . And the even more interesting stackable car from MIT:
>
> http://www.inhabitat.com/2007/11/13/transportation-tuesday-mits-stackable-ci
> ty-car/
>
> And this interesting tidbit:
>
> "Why does a gas lantern use a silk mantle? How does it produce such intense
> light -- BW, Santa Clara, CA
>
> The mantle of a lantern is actually a ceramic ash. The silk itself burns
> away completely and leaves behind only of the oxides of materials that were
> incorporated in the silk mantle when it was manufactured. The principal
> oxide formed when the standard Welsbach mantle is burned is thorium oxide,
> with a few percent of cerium oxide and other oxides. This use of thorium
> oxide or thoria, is a rare example of a radioactive element (thorium is
> radioactive) permitted in common household use. Thoria glows brightly when
> heated because it can tolerate extremely high temperatures without melting
> and because it is a very effective emitter of thermal radiation at
> temperatures of roughly 2200° C."
I think that's rather out of date. Mantles have not contained
thorium for a long time (at least, not in the UK).
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Robert Green
news:18al449g45ucap3mk...@4ax.com...
> On Sat, 7 Jun 2008 06:46:48 -0400, "Robert Green"
> <ROBERT_G...@YAH00.COM> wrote in message
> <rYadnVE6-IgY-tfV...@rcn.net>:
>
> >Would another way to say that be the light level is determined by the
> >point on the sine wave where the gate pulse arrives and that that unit
> >stays on until the
> >end of the cycle, no matter what happens afterward in that cycle?
> ^^^^^ ^^^^^
> half-cycle half-cycle
My bad again. Should have said "Stays on until the zero crossing is
reached."
> >So it's not possible to have a sine wave that has four "bands" of on/off
> >pulses?
>
> Right. Only one per zero-crossing = two per complete cycle = one per
> half-cycle..
One chop per "hump" - I can remember that. It sounded so plausible that a
lot of little chops were possible, especially when Isaac reported that there
were additional (although unused) pulses on the gate line beyond the
triggering pulse. It also sounds like the triac process is something of an
avalanche-like process: easy to start with very little energy required but
hard to stop when large amounts of energy begin to flow.
I used to think triacs and thyristors worked the same way, but I recall that
my Vivitar 283 fossil flash is able to meter out very short pulses from a
large capacitor by using a photoreceptor of some sort that can measure and
react to flash intensity. I'll see what Google has to say . . .
> >Or is it just that way for the X-10 modules?
>
> This is true for all TRIAC-based dimming of AC.
> >I thought, when you talked about pulses, that each one of them turned on
> >the triac for a tiny bit of time, and that all of them added together in
> >each cycle increased the power output. That would require switch the
> >triac on and off multiple timeswithin the cycle. That description is
> >true of how all the chopped A/C cycles add up, but I think you're saying
> >the pulses that follow are not having any effect on the state of the
> >triac.
>
> Right. Dimming by TRIACs is called "phase-control" dimming for a reason.
Makes sense to me!
> One can characterize the amount of dimming by stating the number of
> degrees after zero crossing ("phase") that the TRIAC goes into conduction.
> The relationship between phase and light output is very non-linear and is
> called the dimmer curve. Turning the TRIAC on as late as 20 degrees (out
> of 180 degrees peer half cycle) still results in nearly 100% light
> output, but less than 10% of fully on if delayed to 110 degrees.
Is that mostly an "area under the curve" sort of issue?
> I have constructed a spreadsheet of conduction ("phase") angle, turn-on
> delay, resulting light intensity for typical incandescent lamp, RMS
> voltage, and DMX-512 and 0-10vdc control signals that can be downloaded at
>
> www.ECOntrol.org/dimmers/TRIACDimmerCalcs_MFHult.pdf
>
> It also provides the relevant equations and graphs of conduction angle vs
> light intensity and conduction angle vs RMS voltage.
I'll take a look. Thanks!
--
Bobby G.
Robert Green
That explains a few things, especially why dimmers get very hot when dimming
at some levels but not others. What I am trying to say is that the heat
output curve looks very unlike a resistive dimmer in the same circuit.
Thanks!
--
Bobby G.
Robert Green
news:134...@news1.IPSWITCHS.CMM...
ROBERT_G...@YAH00.COM (Robert Green) writes:
>
> | As I looked at the mod schematic, I realized that the switching was
> | occurring without any polarity reversal of the trigger.
>
> No, you were right the first time. The direction of the gate current is
> reversing in step with the line, keeping the triggering in the more
sensitive
> quadrants.
I'm going to have to trace this out through the schematic. Do you know of
any tools that do a "schematic debugging" the way some software debugger
tools work where each line of code executes in a window that displays
variable states, etc? I've heard designers talk about simulators but I
don't know what they use or how it works. I would like to see something
that would tell me what a voltmeter/scope/logic probe would see at a
particular point in the circuit for each state change. Not sure I explained
that well . . . Anyway, so you're saying if I were to put a probe on that
line going to the triac gate, it would be DC pulse; positive when applied to
the first half of the AC cycle and then negative for the second half?
> The unmodified module uses its own DC supply to drive the gate
> current independent of the line polarity. Using the more sensitive
quadrants
> (or, in general, using two quadrants with the same sensitivity) keeps the
> triggering times as symmetrical as possible minimizing the DC component in
> the output.
I'm confused again. If I applied the probe on the unmodified mod, would I
only see positive pulses?
> | I am assuming that
> | the pulse has to be given after each ZC because the triac has turned
itself
> | off because of a lack of current flow.
>
> You assume correctly.
Slowly, it's becoming more clear how these things work.
Neat. The whole concept of AC current is pretty interesting.
http://en.wikipedia.org/wiki/Alternating_current
I think I have a bit of reading to do but I am thinking the lamp module is a
small enough device to trace out thoroughly. Maybe I can even bring myself
to trying the mod in question to make them into "dim-free" devices.
Thanks for the explanations. They might even sink in - eventually. (-:
--
Bobby G.
Robert Green
news:484b956e$0$663$5a6a...@news.aaisp.net.uk...
Probably not here either. I do believe that they are still using
radioactive materials in smoke detectors, although that could be woefully
out of date information, too. Thanks for the update. Now I get to unlearn
a fact I learned while trying to learn other facts. Unlike books which
usually at least have a copyright date, there's an awful lot of undated
information floating around on the net.
--
Bobby G.
Robert Green
> > <stuff snipped>
> > Would another way to say that be the light level is determined by the
point
> > on the sine wave where the gate pulse arrives and that that unit stays
on
> > until the end of the cycle, no matter what happens afterward in that
cycle?
>
> It's the end of the next half-cycle (the next zero crossing), but
> otherwise, yes; that's what happens.
OK - this is getting clearer. It doesn't conduct unless "goosed" by gate
current and once it's on, the gate current becomes essentially irrelevant
until the after the AC half cycle ends and the reversal of polarity shuts
off current flow through the triac.
> > So it's not possible to have a sine wave that has four "bands" of on/off
> > pulses? Or is it just that way for the X-10 modules? I thought, when
you
> > talked about pulses, that each one of them turned on the triac for a
tiny
> > bit of time, and that all of them added together in each cycle increased
the
> > power output. That would require switch the triac on and off multiple
times
> > within the cycle. That description is true of how all the chopped A/C
> > cycles add up, but I think you're saying the pulses that follow are not
> > having any effect on the state of the triac.
>
> Correct; they do not. Once a triac is conducting, it's very difficult to
> get it to turn off any way except removing the voltage across it
> (actually, it's removing the current through it that makes it turn off).
Are there other devices that can interrupt current flow with a gate trigger?
> > After reading more, what I envision now from your description is a
sliding
> > window sort of thing where the amount of current flowing depends on how
far
> > you slide the ON window to the left-most window stop, which in this
case, is
> > the zero crossing. That sound anywhere near right?
>
> Right on. But think about how a half-sine looks -- a linear increase in
> on-time does NOT result in a linear increase in power delivered to the
> load.
Right. This looks very much like an "area under the curve" sort of problem.
> > > > I assume that would me they are obviously much shorter in
> > > > duration than 1/2 the AC cycle. It sounds like they are
"rechopping"
> > the
> > > > pulse into smaller pulses and that they aggregate to give the
desired
> > end
> > > > level. I am not explaining that well, I fear. It seems like there
are
> > two
> > > > pulse aggregations, a wheel within a wheel Ixion sort of thing.
> > >
> > > The fact that there is a train of pulses is probably an artifact of
the
> > > way the IC in the X-10 unit accomplishes phase delay (to retard the
> > > timing of the gate drive).
>
> There is exactly one "on" interval per half cycle;
My "one chop per hump" interpretation. (-:
> if it is very short,
> no appreciable power is delivered to the load. If it is nearly a full
> half-cycle in duration, nearly full power is delivered.
>
> > So it might even be possible it's really just noise with no particular
> > function but no particular harm to the operation of the module.
>
> It's not noise; it's a regular string of pulses.
I thought that any signal other than the one you wanted could be considered
noise.
> > I assume you detected it with some sort of logic analyzer?
>
> No; just an ordinary oscilloscope.
I guess it's time to finally unbox my Radio Shack pen oscilloscope.
<stuff snipped>
> > > I was interested in using X-10 units to remotely control stuff other
> > > than lamps and coffee pots. Getting an optically isolated variable
width
> > > pulse was a good starting place. I was not going to use that signal to
> > > drive a triac in amy way.
> >
> > Sounds interesting. Wouldn't such an extension give you trouble with
> > standard repeaters?
>
> I didn't care about repeaters. What I wanted to do was control a large
> number of electrical valves for an irrigation system. As I said, the
> problem was that it was not repeatable -- the same number of "brighten"
> pulses did not always result in the same pulse width, and so I could not
> reliably select which irrigation circuit I wanted to run.
Too bad. What's a large number? There's a lot of headroom with 256
discrete X-10 addresses, even if you're controlling a modern home.
<stuff snipped>
> > So with the capacitor, the signal is being smoothed out from a pulse
train
> > to voltage level. Usenet II is going to need a whiteboard. At least
ten
> > times now I've wanted to show something with a simple sketch. What
does
> > that pulse train look like? Is it a square wave with the lowermost part
at
> > 0 volts and the uppermost part at Vcc+ (not sure if that the right
term).
> > Would the resulting DC level be Vcc+/2 or something close to that?
>
> Honestly, I don't remember. I was doing this some years back. All I
> recall is that starting from "full dim" there was one narrow, "square"
> pulse, very close to the following zero-crossing. As "brighten" pulses
> were sent, that pulse always moved earlier in the half-cycle, but as it
> moved, it was joined by progressively more and more that looked just
> like it. The "extra" pulses occurred later in the phase than the one
> that turned the triac on, and so they had no effect on the operation of
> the unit.
Interesting. I assume that with X-10's parsimonious Scotch heritage that
they decided that as long as it didn't have a negative impact on
performance, they didn't need to add any circuitry to filter it out.
> > > > > 2) Change the 2.2 k resistor to 12 k.
> > > >
> > > > You would normally change a resistor value to change a time value in
a
> > > > dependent RC circuit or to protect some other component from drawing
too
> > > > much current, correct?
> > >
> > > Yup. In this case, I raised the value to allow a smaller capacitor to
be
> > > used to get the time constant I wanted.
> >
> > At least I remember that much from reading my 555 cookbook 20+ years
ago.
> >
> > > > > 3) Connect a 0.1 mfd. capacitor (ceramic is fine) from the cathode
of
> > > > > the diode to V-
> > >
> > > That's the cap that integrates the pulse train into a DC value
> >
> > You said "average DC level" before. Is it safe to assume that DC value
is
> > still going to show some trace of the underlying pulses because of how
it
> > has been generated? Is that called ripple or is that something else
> > entirely?
>
> Ripple would be a good term to use. The trade-off is that as you
> increase the time constant to reduce the ripple, you also increase the
> time the unit takes to respond to changes in the pulse width.
This sounds like one reason that circuit designers are always tweaking the
values of capacitors and resistors between board versions: to optimize the
various design trade-offs. (-:
> > > > > 4) Change the 330 ohm resistor to 2.2 k
> > >
> > > Simplistically, the 12K resistor determines how fast the cap charges
> > > (but not discharges, because the diode prevents that), while the 2.2K
> > > controls the discharge time.
> >
> > Is that capacitor discharging during the time the pulse is at zero, thus
> > providing current in the circuit where there would have been none
without
> > it?
>
> Yup.
It seems as if the R/C circuit is one of the most common electronic
"building blocks."
<stuff snipped>
> > Thanks for the encouragement and the input. I feel a little like I felt
on
> > the first day of kindergarten when I saw all the sixth graders writing
in
> > cursive, reading big books and most impressive of all, taking the stairs
two
> > at a time!
> >
> > I suppose this means I'll have to finally break down and open an account
at
> > Digikey or Mouser. (=;
>
> Learn how to take old gear apart and scavenge the parts. Not only do you
> get all sorts of good stuff, but you improve your (un)soldering skills
> at the same time.
I've been stripping components for a long, long time. When something like a
stereo breaks, I put it aside until it's obsolete (that wasn't really the
plan, but that's what always happens). Then I strip out the more useful
looking parts. Now, perhaps, I can finally *do* something with them. I've
been toying with the idea of making an interface to Jeff's XTB to read the
raw data bits from the line into a data file. He assures me that it's as
easy as pie, but I am not so sure. The problem is that my meager
bitwhacking and soldering skills stand in the way! I think first I will try
to trace and document the lamp module as thoroughly as I can. I'll do that
in a separate thread after a do some searching to make sure it hasn't
already been done to death. Something tells me that by tracing the circuit
through, I'll pick up a lot that didn't sink in just reading the protocol
docs.
Thanks again for all the help.
--
Bobby G.
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
That's right. No matter how fast the device switches on, making the
transition at the peak of the half-cycle is going to take longer than
when it's near one end or the other. Hence, more heat is generated.
Isaac
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
> "isw" <i...@witzend.com> wrote in message
> news:isw-21C5D4.2...@newsgroups.comcast.net...
>
> > > <stuff snipped>
>
> > > So it's not possible to have a sine wave that has four "bands" of on/off
> > > pulses? Or is it just that way for the X-10 modules? I thought, when
> you
> > > talked about pulses, that each one of them turned on the triac for a
> tiny
> > > bit of time, and that all of them added together in each cycle increased
> the
> > > power output. That would require switch the triac on and off multiple
> times
> > > within the cycle. That description is true of how all the chopped A/C
> > > cycles add up, but I think you're saying the pulses that follow are not
> > > having any effect on the state of the triac.
> >
> > Correct; they do not. Once a triac is conducting, it's very difficult to
> > get it to turn off any way except removing the voltage across it
> > (actually, it's removing the current through it that makes it turn off).
>
> Are there other devices that can interrupt current flow with a gate trigger?
Yes. There are gate-turn-off (GTO) thyristors:
http://en.wikipedia.org/wiki/Gate_turn-off_thyristor
> > Right on. But think about how a half-sine looks -- a linear increase in
> > on-time does NOT result in a linear increase in power delivered to the
> > load.
>
> Right. This looks very much like an "area under the curve" sort of problem.
Close, but more complex, because the load (assuming an incandescent
lamp) is not constant. The resistance of a lamp filament is lowest when
it's cold (which is why a burn-out so often occurs when it's switched
on), and rises as the filament heats up.
> > > So it might even be possible it's really just noise with no particular
> > > function but no particular harm to the operation of the module.
> >
> > It's not noise; it's a regular string of pulses.
>
> I thought that any signal other than the one you wanted could be considered
> noise.
That's a simplistic definition, although it sometimes works.
> > I didn't care about repeaters. What I wanted to do was control a large
> > number of electrical valves for an irrigation system. As I said, the
> > problem was that it was not repeatable -- the same number of "brighten"
> > pulses did not always result in the same pulse width, and so I could not
> > reliably select which irrigation circuit I wanted to run.
>
> Too bad. What's a large number? There's a lot of headroom with 256
> discrete X-10 addresses, even if you're controlling a modern home.
That National chip (an LED bar generator) has ten outputs, and it can be
hooked up sort of like a ten-value A-to-D converter. Having to use an
X-10 module for each and every sprinkler valve would work, but has even
more problems -- not least of which is the tendency of the things to
turn on for no evident reason ("noise" if yo will).
> <stuff snipped>
>
> > > So with the capacitor, the signal is being smoothed out from a pulse
> train
> > > to voltage level. Usenet II is going to need a whiteboard. At least
> ten
> > > times now I've wanted to show something with a simple sketch. What
> does
> > > that pulse train look like? Is it a square wave with the lowermost part
> at
> > > 0 volts and the uppermost part at Vcc+ (not sure if that the right
> term).
> > > Would the resulting DC level be Vcc+/2 or something close to that?
> >
> > Honestly, I don't remember. I was doing this some years back. All I
> > recall is that starting from "full dim" there was one narrow, "square"
> > pulse, very close to the following zero-crossing. As "brighten" pulses
> > were sent, that pulse always moved earlier in the half-cycle, but as it
> > moved, it was joined by progressively more and more that looked just
> > like it. The "extra" pulses occurred later in the phase than the one
> > that turned the triac on, and so they had no effect on the operation of
> > the unit.
>
> Interesting. I assume that with X-10's parsimonious Scotch heritage that
> they decided that as long as it didn't have a negative impact on
> performance, they didn't need to add any circuitry to filter it out.
Yup.
> > Ripple would be a good term to use. The trade-off is that as you
> > increase the time constant to reduce the ripple, you also increase the
> > time the unit takes to respond to changes in the pulse width.
>
> This sounds like one reason that circuit designers are always tweaking the
> values of capacitors and resistors between board versions: to optimize the
> various design trade-offs. (-:
Well, yes, but usually a *real* designer will have a good notion of what
values to use and not have to try a bunch of things to see what works.
Changing a board layout can slightly alter things like the capacitance
between adjacent traces, and that can cause instability, especially if
the original values were determined "experimentally" by someone who
didn't understand worst-case design, margining, and so on.
>
> > > > > > 4) Change the 330 ohm resistor to 2.2 k
> > > >
> > > > Simplistically, the 12K resistor determines how fast the cap charges
> > > > (but not discharges, because the diode prevents that), while the 2.2K
> > > > controls the discharge time.
> > >
> > > Is that capacitor discharging during the time the pulse is at zero, thus
> > > providing current in the circuit where there would have been none
> without
> > > it?
> >
> > Yup.
>
> It seems as if the R/C circuit is one of the most common electronic
> "building blocks."
Yes, it is. Both components are cheap, and easy to get in a wide range
of values.
Here's an interesting item: Of all physical units (weight, volume,
current, voltage, heat, ...) resistance is available over by far the
widest range, easily from under a micro-ohm to over a hundred megaohms
-- say fourteen orders of magnitude. That's why electrical simulations
of other phenomena are so easy.
Isaac
Dan Lanciani
| "Dan Lanciani" <ddl@danlan.*com> wrote in message
| news:134...@news1.IPSWITCHS.CMM...
| > In article <VtCdnaFcKJIC0NfV...@rcn.net>,
| ROBERT_G...@YAH00.COM (Robert Green) writes:
| >
| > | As I looked at the mod schematic, I realized that the switching was
| > | occurring without any polarity reversal of the trigger.
| >
| > No, you were right the first time. The direction of the gate current is
| > reversing in step with the line, keeping the triggering in the more
| sensitive
| > quadrants.
|
| I'm going to have to trace this out through the schematic. Do you know of
| any tools that do a "schematic debugging" the way some software debugger
| tools work where each line of code executes in a window that displays
| variable states, etc?
No, but some of the simulators might be close.
| I've heard designers talk about simulators but I
| don't know what they use or how it works. I would like to see something
| that would tell me what a voltmeter/scope/logic probe would see at a
| particular point in the circuit for each state change. Not sure I explained
| that well . . . Anyway, so you're saying if I were to put a probe on that
| line going to the triac gate, it would be DC pulse; positive when applied to
| the first half of the AC cycle and then negative for the second half?
It would be a more complicated waveform, but more-or-less yes (and for
some definition of "first" and "second") for the modified module.
| > The unmodified module uses its own DC supply to drive the gate
| > current independent of the line polarity. Using the more sensitive
| quadrants
| > (or, in general, using two quadrants with the same sensitivity) keeps the
| > triggering times as symmetrical as possible minimizing the DC component in
| > the output.
|
| I'm confused again. If I applied the probe on the unmodified mod, would I
| only see positive pulses?
The module uses a negative supply, so only negative. Keep in mind that
the zero-volt reference of the module is the hot side of the line, so you
have to be careful with such measurements.
| I think I have a bit of reading to do but I am thinking the lamp module is a
| small enough device to trace out thoroughly.
It's small, but it's also an exercise in clever cost reduction. The
aforementioned use of the hot side of the line as a logic zero-volt
reference lets them drive the triac easily without isolation, but it
can be confusing and dangerous if you don't understand what is going
on. It would not be my first choice to learn circuit analysis...
Dan Lanciani
ddl@danlan.*com
Robert Green
<stuff snipped>
>> Are there other devices that can interrupt current flow with a gate
>> trigger?
> Yes. There are gate-turn-off (GTO) thyristors:
> http://en.wikipedia.org/wiki/Gate_turn-off_thyristor
So that's how my auto-thyristor flash works!
> > > Right on. But think about how a half-sine looks -- a linear increase
in
> > > on-time does NOT result in a linear increase in power delivered to the
> > > load.
> >
> > Right. This looks very much like an "area under the curve" sort of
problem.
>
> Close, but more complex, because the load (assuming an incandescent
> lamp) is not constant. The resistance of a lamp filament is lowest when
> it's cold (which is why a burn-out so often occurs when it's switched
> on), and rises as the filament heats up.
I see
>
>>>> So it might even be possible it's really just noise with no particular
>>>> function but no particular harm to the operation of the module.
> > >
> > > It's not noise; it's a regular string of pulses.
> >
> > I thought that any signal other than the one you wanted could be
> > considered noise.
>
> That's a simplistic definition, although it sometimes works.
I'm a simplistic guy. (0: I assume the anything that is non-random
shouldn't really be called noise.
>>> I didn't care about repeaters. What I wanted to do was control a large
>>> number of electrical valves for an irrigation system. As I said, the
>>> problem was that it was not repeatable -- the same number of "brighten"
>>> pulses did not always result in the same pulse width, and so I could not
>>> reliably select which irrigation circuit I wanted to run.
> >
> > Too bad. What's a large number? There's a lot of headroom with 256
> > discrete X-10 addresses, even if you're controlling a modern home.
>
> That National chip (an LED bar generator) has ten outputs, and it can be
> hooked up sort of like a ten-value A-to-D converter. Having to use an
> X-10 module for each and every sprinkler valve would work, but has even
> more problems -- not least of which is the tendency of the things to
> turn on for no evident reason ("noise" if yo will).
Indeed. The only (marginal) solution for me is double-stacking modules. So
far, only operator error has inadvertently activated something I've got
"double-stacked" appliance modules but I still would be reluctant to control
water valves without some other independent verification of operation.
> > <stuff snipped>
>> This sounds like one reason that circuit designers are always tweaking
>> the values of capacitors and resistors between board versions: to
optimize
>> the various design trade-offs. (-:
> Well, yes, but usually a *real* designer will have a good notion of what
> values to use and not have to try a bunch of things to see what works.
> Changing a board layout can slightly alter things like the capacitance
> between adjacent traces, and that can cause instability, especially if
> the original values were determined "experimentally" by someone who
> didn't understand worst-case design, margining, and so on.
Good point.
<stuff snipped>
> > It seems as if the R/C circuit is one of the most common electronic
> > "building blocks."
>
> Yes, it is. Both components are cheap, and easy to get in a wide range
> of values.
>
> Here's an interesting item: Of all physical units (weight, volume,
> current, voltage, heat, ...) resistance is available over by far the
> widest range, easily from under a micro-ohm to over a hundred megaohms
> -- say fourteen orders of magnitude. That's why electrical simulations
> of other phenomena are so easy.
And now there's a fourth basic component: the memristor! (The other three
are resistors, capacitors and inductors.)
"The newly discovered circuit element - called a memristor - could enable
mobile phones that can go weeks or longer without a charge, PCs that start
up instantly and laptops that retain your session information long after the
battery dies. It also could challenge flash memory: the HP discovery would
be faster, use less power and take up far less space than today's flash."
http://news.google.com/news?hl=en&um=1&tab=wn&q=memristor&btnG=Search+News
--
Bobby G.
isw
"Robert Green" <ROBERT_G...@YAH00.COM> wrote:
I think so, but sometimes it can be *really* hard to tell the difference
(cf. "pseudorandom"). Pseudorandom patterns are regularly used for
encryption. If they were *truly* random ,they wouldn't be very useful,
but if their pattern could be determined, even with great effort, they
would be worthless.
Isaac