Whole house fan motor

[telengard]

Just recently purchased a house and it has a whole house fan.
Unfortunately, the folks who installed the A/C disconnected the
motorized louvers to get into the crawl space a couple months ago and
I'm not sure exactly how it was wired. In the crawl space there is a
black (which had a wire nut on it) and bare wire and a white wire
which looks like it was curled up to not use it (it is not stripped).
The motor on the louvers has 2 black wires and a green wire.
Unfortunately, I could not find any documentation on the motor. We
have 2 separate switches so the louvers are independently controlled.

Just wondering what the wires on the motor are. The motor is a Dayton
Motor Shutter Model 2C904 115V 60Hz.

Any info greatly appreciated.

[Jamie]

the two wires are your 120 volt AC lines from the motor..

in your case, you can connect the black wires from the motor to
the white and black wire that is capped off..

the green wire from the motor is the ground which is connected to the
bare wire you see..

P.S.
since there is a wire nut on the black wire, this tells me it could
be alive or at some point may come alive...
I would first kill the circuit that supplies that before attaching the
last black lead from the motor to that one.

Also, this appears to be a single direction motor, this tells me that
the shutter drive must not have a stop on it or it just keeps going
around and around.. Most likely has an eccentric wheel or a wheel with
an offset swing arm on it.


Jamie

[telengard]

On May 5, 8:12 pm, Jamie

Hi Jamie,

Thanks for the info, I have been shutting off the breaker when working
with this. I guess I'm surprised that the white wire would be used, I
guess the A/C guys may have just twisted it up for safety. That must
be the missing piece, I had tested both blacks to the one black
(assuming the white was was wrapped up as it was not used).

And yes, the motor has some kind of arm attached to it w/ a spring.

[Tom Biasi]

When you say the white wire was wrapped, is it wrapped with black tape?
If so it is probably a hot from the switch.

[John Fields]

---
Go to:
http://www.grainger.com

and type 2C904 into the search box.

--
JF

[tele...@gmail.com]

> When you say the white wire was wrapped, is it wrapped with black tape?
>
> If so it is probably a hot from the switch.

Sorry, I should have been more precise. The white wire was not stripped, was not in a wire nut, and was coiled up whereas the other 2 wires were straight (for lack of a better term). In other words, it looked like it wasn't being used, or this was done to prevent a short or something, although I would have thought having the dangling black and bare would be just as bad.

[amdx]

> exti

First I'd like to say, I had a home with a whole house fan, and it was
great on those summer nights in Michigan. Just crack the windows in the
room about 4" and turn on the fan. Great breeze comes through.

There may be a reason it is disconnected ( doesn't work?). I would
first verify operation of the louver controller. I have enough extension
cords around that I would just wire a cord to it and plug it in. If it
opens, unplug it and see if it closes.
If it works, I would then follow the wiring from the motor and see if
there is a parallel wiring connection that could be connected to the
louver controller.
Here is a link that gave me the little I know about electric louvers.

Please get your own understanding, before attempting repair.

(istr, my louvers were opened by the draft that came through)
From what I read, the louver controller opens with power on and closes
when power is removed.
The second link refers to the replacement model that Grainger
recommends for your unit.

> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CGAQFjAC&url=http%3A%2F%2Fwww.captiveaire.com%2FMANUALS%2FMAKEUPAIR%2FSUPPLYFANTRAINING%2FAWV%2FDamper%2520Motor%2520Installation%2520Instructions.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGdNM-SJGseowbcLXueCYuzJlv05Q&sig2=dlsAN3pdeP1yRQ-Xip_Rzw&bvm=bv.45960087,d.eWU&cad=rja

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CGAQFjAC&url=http%3A%2F%2Fwww.captiveaire.com%2FMANUALS%2FMAKEUPAIR%2FSUPPLYFANTRAINING%2FAWV%2FDamper%2520Motor%2520Installation%2520Instructions.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGdNM-SJGseowbcLXueCYuzJlv05Q&sig2=dlsAN3pdeP1yRQ-Xip_Rzw&bvm=bv.45960087,d.eWU&cad=rja

> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CGUQFjAD&url=http%3A%2F%2Fwww.charleysgreenhouse.com%2Flearn_more%2Fpdf%2FC3259_Shutter_Motor_Manual.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGWafTifnKroTJdG9932mXFd_Hqxg&sig2=ntWF2coocobBbvKJXyNgSw&bvm=bv.45960087,d.eWU

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CGUQFjAD&url=http%3A%2F%2Fwww.charleysgreenhouse.com%2Flearn_more%2Fpdf%2FC3259_Shutter_Motor_Manual.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGWafTifnKroTJdG9932mXFd_Hqxg&sig2=ntWF2coocobBbvKJXyNgSw&bvm=bv.45960087,d.eWU

[Uncle Steve]

Back again for some more abuse.

I'm building a 12V battery charger that will be controlled by a small
low-power microcontroller. I've not yet hooked up the
microcontroller, but most of the code is written and I'm trying to
finalize the charger electronics before I hook it up.

The circuit is very simple. An 18V 2A transformer, a bridge
rectifier, and filter capacitor feeds a main power rail. A 5V
regulator produces a few mA for the microcontroller, which I won't show
here. The charger is more or less as follows, though I will leave out
the resistor/divider taps which hook up to the ADC channels on the
micro.


+18VDC ---------------------------+
Q1 c e | D1 R1
-----\_/--------->|----\/\/\--------+12(batt)
b| |
+------+ |
| | +--+----------+
/ Q2 e\_/c |
R1 \ |b |
/ | e |c Q3
\ +--\/\/\------\_/
| R2 |b
| | R3 SW1
LED1 \_/ +--\/\/\-- \-- +5V
---
|
|
GND --------------+------------------------------------ GND(batt)


Q1 - MJE3055
D1 - 1N4004
R1 - .5 5W

Q2 - BC557
R2 - 200K

Q3 - 2N2222
R3 - 1K


The microcontroller will strobe R3 with PCM at about 488HZ with a duty
cycle dependant on the charge profile. R1 is the sense resistor and
permits measuring instantaneous charge current. I've got the battery
attached and can watch the voltage rise (and settle) as I manually
engage a switch attached as shown. The battery voltage as it came
from Wallmart was about 12.7V. Charge current with this circuit
is 1.4A at this point in its charge cycle. The heat-sink gets rather
warm, but it isn't all that big and I'm going to target 3 or 4A as the
peak charge current so I'll probably substitute a TO-3 package with a
much beefier heat-sink when I put the project in an enclosure.

So far, so good. The output of Q1 shows .6V ripple. Attaching my
scope to the base of Q1 shows an idle (SW off) voltage of 16mV and a
120Hz signal with a 70mVpp with a duty cycle of 17%. I'm not exactly
sure where this signal is coming from, although its frequency suggests
a causal relationship with the AC mains. There does not appear to be
any ripple on the 5V rail, but my scope isn't good enough to really
zoom in on it.

The other side of the coin is that the Q2/Q3 network seems to be
rather sensitive. When I pass my hand over the breadboard the
distortion described above doubles and I can get an amplitude of 1V on
that distortion by standing up suddenly while sitting in front of the
idle circuit. It is difficult to say what is happening because I can
double the distortion by attaching the scope to a wall-wart USB
charger, and I know I haven't yet calibrated the scope all that well
either. (Scope shows 4.5V from the 5V regulator.) But the fact
that I can affect the circuit just by moving things in the general
vicinity is, um, rather shocking.

Besides installing the circuit in a metal case, are there any easy
solutions to fix that 16mV idle voltage? Should I just change the
BC557 to a 2n2222 and work out how many of what kind of resistors I
need to supply the 3055 with the mA it needs to dump several amps into
the battery? I like this version because it is easy to set up and has
a low part count, but I'd really like to get rid of the noise and the
sensitivity to movement.


Regards,

Uncle Steve

--
There should be a special word in the English language to identify
people who create problems and then turn around and offer up their own
tailor-made bogus non-solutions designed to completely avoid the root
causes of the situation under consideration. 'Traitor' might be a
good choice, but lacks the requisite specificity. One of the problems
with contemporary English is it lacks many such words that would
otherwise categorically identify certain kinds of person, place, or
thing -- making it difficult or impossible to think analytically about
such objects. These shortcomings of the English lexicon are
representative of Orwellian linguistics at work in the real world.

[Jim Thompson]

Yep, Some powered louvers I've seen sense air pressure and open.

> From what I read, the louver controller opens with power on and closes
>when power is removed.
> The second link refers to the replacement model that Grainger
>recommends for your unit.
>
>> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CGAQFjAC&url=http%3A%2F%2Fwww.captiveaire.com%2FMANUALS%2FMAKEUPAIR%2FSUPPLYFANTRAINING%2FAWV%2FDamper%2520Motor%2520Installation%2520Instructions.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGdNM-SJGseowbcLXueCYuzJlv05Q&sig2=dlsAN3pdeP1yRQ-Xip_Rzw&bvm=bv.45960087,d.eWU&cad=rja
>
>http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CGAQFjAC&url=http%3A%2F%2Fwww.captiveaire.com%2FMANUALS%2FMAKEUPAIR%2FSUPPLYFANTRAINING%2FAWV%2FDamper%2520Motor%2520Installation%2520Instructions.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGdNM-SJGseowbcLXueCYuzJlv05Q&sig2=dlsAN3pdeP1yRQ-Xip_Rzw&bvm=bv.45960087,d.eWU&cad=rja
>
>> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CGUQFjAD&url=http%3A%2F%2Fwww.charleysgreenhouse.com%2Flearn_more%2Fpdf%2FC3259_Shutter_Motor_Manual.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGWafTifnKroTJdG9932mXFd_Hqxg&sig2=ntWF2coocobBbvKJXyNgSw&bvm=bv.45960087,d.eWU
>
>http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CGUQFjAD&url=http%3A%2F%2Fwww.charleysgreenhouse.com%2Flearn_more%2Fpdf%2FC3259_Shutter_Motor_Manual.pdf&ei=6MaHUdSFE4f09gSi54HYDw&usg=AFQjCNGWafTifnKroTJdG9932mXFd_Hqxg&sig2=ntWF2coocobBbvKJXyNgSw&bvm=bv.45960087,d.eWU
>

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

[Uncle Steve]

On Mon, May 06, 2013 at 12:01:44PM -0400, Uncle Steve wrote:
> +18VDC ---------------------------+
> Q1 c e | D1 R1
> -----\_/--------->|----\/\/\--------+12(batt)
> b| |
> +------+ |
> | | +--+----------+
> / Q2 e\_/c |
> R1 \ |b |
> / | e |c Q3

Ah, sorry. R1 immediately above is 2.2K and it's the other R1 that is
.5 ohms.

[Tim Wescott]

Start a new thread! This isn't even remotely related to fan motors!

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

[amdx]

On 5/6/2013 11:01 AM, Uncle Steve wrote:
> Back again for some more abuse.

Where's Phil when somebody really deserves abuse?
Mikek

[Uncle Steve]

On Mon, May 06, 2013 at 02:35:52PM -0500, Tim Wescott wrote:

> On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve wrote:
>
> > Back again for some more abuse.
> >

> > I'm building a 12V battery charger that will be controlled by a small
> > low-power microcontroller. I've not yet hooked up the microcontroller,
> > but most of the code is written and I'm trying to finalize the charger
> > electronics before I hook it up.
> >
> > The circuit is very simple. An 18V 2A transformer, a bridge rectifier,
> > and filter capacitor feeds a main power rail. A 5V regulator produces a
> > few mA for the microcontroller, which I won't show here. The charger is
> > more or less as follows, though I will leave out the resistor/divider
> > taps which hook up to the ADC channels on the micro.
> >
> >

> > +18VDC ---------------------------+
> > Q1 c e | D1 R1
> > -----\_/--------->|----\/\/\--------+12(batt)
> > b| |
> > +------+ |
> > | | +--+----------+
> > / Q2 e\_/c |
> > R1 \ |b |
> > / | e |c Q3
> > \ +--\/\/\------\_/
> > | R2 |b
> > | | R3 SW1
> > LED1 \_/ +--\/\/\-- \-- +5V
> > ---
> > |
> > |
> > GND --------------+------------------------------------ GND(batt)
> >
> >

Sorry. My newsreader crashes when I 'post' so I have to reply to
something and then delete the references header, which I forgot to do
in this case. What happens next is dependant on the newsreader you
use.

[Uncle Steve]

On Mon, May 06, 2013 at 12:01:44PM -0400, Uncle Steve wrote:
> Back again for some more abuse.
>
> I'm building a 12V battery charger that will be controlled by a small
> low-power microcontroller. I've not yet hooked up the
> microcontroller, but most of the code is written and I'm trying to
> finalize the charger electronics before I hook it up.
>
> The circuit is very simple. An 18V 2A transformer, a bridge
> rectifier, and filter capacitor feeds a main power rail. A 5V
> regulator produces a few mA for the microcontroller, which I won't show
> here. The charger is more or less as follows, though I will leave out
> the resistor/divider taps which hook up to the ADC channels on the
> micro.
>
>
> +18VDC ---------------------------+
> Q1 c e | D1 R1
> -----\_/--------->|----\/\/\--------+12(batt)
> b| |
> +------+ |
> | | +--+----------+
> / Q2 e\_/c |

R4 \ |b |

> / | e |c Q3
> \ +--\/\/\------\_/
> | R2 |b
> | | R3 SW1
> LED1 \_/ +--\/\/\-- \-- +5V
> ---
> |
> |
> GND --------------+------------------------------------ GND(batt)
>
>
> Q1 - MJE3055
> D1 - 1N4004
> R1 - .5 5W
>
> Q2 - BC557
> R2 - 200K
>
> Q3 - 2N2222
> R3 - 1K

R4 - 2k

As suggested, I moved this out of the existing thread. It was an
mistake that I did not remove the references header.

At any rate, I set up a separate pair of 2n2222, 10K resistor, and
BC557 similar to the input stage above as well as a LED. Then I
connected a small spool of insulated wire to the base of the 2n2222
and then let it out a couple of feet until the LED stayed onish without
my hands being near the device.

The result is a strong 6-7MHz signal for a bunch of cycles and then
some dead time. It looks like there could be some FM in there, and on
the high part of the cycle there appears to be an additional small
signal, but I can't resolve any detail with my equipment.

If I hold the spool in my hand the amount of on time changes
considerably depending how much of my hand is in contact with the
plastic and insulation. With palm open, there is one rise/fall cycle
at about 6.5MHz when my hand is about 6in from the wire. As my hand
gets closer, a second peak appears and so on until there is a train of
several dozen cycles at or near the measured frequency.

Any idea what the hell that signal might be?

[George Herold]

> Tim Wescott, Communications, Control, Circuits & Softwarehttp://www.wescottdesign.com- Hide quoted text -
>
> - Show quoted text -

Yes a new thread is in order. The middle of the circuit is weird. (at
least to me.) Your moving hand thing is a sure sign of electrostatic
pickup.

George H.

[amdx]

Fix your newsreader!

[Tim Wescott]

I'm not making sense of your schematic. If Q2 is a PNP it should have
its emitter to +18V and its collector to the base of Q1. (Q1 should have
its collector _connected_!!). Q3 is configured to deliver current to the
base of Q2, but it needs to pull current -- ?!?!?!?!

Could you be showing the emitters and collectors of Q2 and Q3 reversed?

If it's doing anything at all (which presumably it is) then amongst your
various transistors you have tons of uncontrolled gain, so it's not
surprising that its oscillating or doing other weird stuff.

What's your goal? A charge current that's proportional to the voltage at
the SW1 end of R3?

I'd have to think about how to take that collection of transistors and
make a stable circuit out of it, but if you're really building to that
schematic then I suspect that you need to make some changes!

Note that if you're charging a lead-acid battery (gel or flood) the ideal
charge profile is to limit both voltage and current. Voltage is limited
to some magic number (which I can never remember -- look it up), and
current is limited either by the charger's capabilities or the
battery's. When the charge of the battery is low it accepts charge at
the constant current, but then as it charges you must drop the current to
hold the voltage constant.

[Uncle Steve]

I started doing that, but the path I went down is superficially
similar to Larry Wall's story and I fear it will be a while yet before
I have running code.

[Uncle Steve]

I don't think so. The arrangement is described as a Sziklai Pair, and
is described at the following URL:

http://www.talkingelectronics.com/projects/TheTransistorAmplifier/TheTransistorAmplifier-P1.html#THEDARLINGTON

> If it's doing anything at all (which presumably it is) then amongst your
> various transistors you have tons of uncontrolled gain, so it's not
> surprising that its oscillating or doing other weird stuff.
>
> What's your goal? A charge current that's proportional to the voltage at
> the SW1 end of R3?

SW1 is a stand in for the TTL level output from a microcontroller pin
and will operate at 488Hz PWM as described above.

> I'd have to think about how to take that collection of transistors and
> make a stable circuit out of it, but if you're really building to that
> schematic then I suspect that you need to make some changes!

The oscillation showing up at the base of Q1 may be the result of some
sort of capacitance issue with Q2/Q3. I fiddled with a few small
ceramic capacitors in a naive fashion, but I did not accomplish
anything other than destroying a 2n2222. I simply haven't
internalized enough information about how these things operate to
figure out what I should do to eliminate the distortion.

> Note that if you're charging a lead-acid battery (gel or flood) the ideal
> charge profile is to limit both voltage and current. Voltage is limited
> to some magic number (which I can never remember -- look it up), and
> current is limited either by the charger's capabilities or the
> battery's. When the charge of the battery is low it accepts charge at
> the constant current, but then as it charges you must drop the current to
> hold the voltage constant.

I understand that. The preliminary figures I have suggest that the
charge voltage should be 13.8V and the float voltage 13.5V.

The current strategy I'm working on will limit the average current
over time with PWM, measuring instantaneous current when Q1 is on to
drive a feedback loop to set PWM duty-cycle. I'll be reading supply
voltage, and voltage at either side of the .5 Ohm sense resister at
various times throughout the PWM cycle. The software will do ADC at
about 125KHz so there's lots of room to average things nicely. I
assume there's no real problem with allowing current to spike at short
intervals if the battery naturally wants more amps than my PS will
supply on a continual basis. I may be wrong, and it may be a simple
matter to install a load resistor with the sense resistor. I'm still
in larval stage so this stuff is still a little mysterious.

[Tim Wescott]

Look again -- I don't think you're there. One huge thing to note: your
Sziklai pair is only going to work well when it's all the way off or all
the way on -- PWM is good, but don't expect it to work in anything
resembling a linear fashion.


+18V Q1 ___ battery
o---------------- ------|___|-----o
\ ^
---
|
|
.-.
| |
| |
'-'
|
|
|<
.---| Q2
| |\
| |
| |
| |
PWM |/ |
o---------| Q3 |
|> |
| |
| |
=== ===
GND GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

[Uncle Steve]

I will consider that, but note that Q1 is NPN. What you propose
suggests I was counting on current-limiting to occur in the wrong
place.

The software feedback loop ought to allow the ideal pulse width to
'fly' automatically at the correct setting, assuming the ADC readings
are reasonably accurate. Theoretically, I should also be able to
detect collapse (?) of the transformer flux if the current draw grows
too large, which would be a nice bonus.

[Jim Thompson]

On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>Back again for some more abuse.
>
>I'm building a 12V battery charger that will be controlled by a small
>low-power microcontroller. I've not yet hooked up the
>microcontroller, but most of the code is written and I'm trying to
>finalize the charger electronics before I hook it up.
>

[snip]

How is the charger "controlled"?

Do you mean that the output CURRENT from the charger will be a
function of the "duty-cycle" from the micro-controller?

Or do you have some other algorithm in mind?

[Uncle Steve]

On Mon, May 06, 2013 at 06:59:01PM -0700, Jim Thompson wrote:
> On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >Back again for some more abuse.
> >
> >I'm building a 12V battery charger that will be controlled by a small
> >low-power microcontroller. I've not yet hooked up the
> >microcontroller, but most of the code is written and I'm trying to
> >finalize the charger electronics before I hook it up.
> >
> [snip]
>
> How is the charger "controlled"?
>
> Do you mean that the output CURRENT from the charger will be a
> function of the "duty-cycle" from the micro-controller?

The average current, yes.

> Or do you have some other algorithm in mind?

I've used a similar technique in other circumstances. In this
instance the ADC measurements of the carger circuit will determine how
much energy will be dumped into the battery at any given time, again
/on average/. Lead acid battery chemistry has significant hysteresis,
so I do not at this time expect any major problems with this strategy.
The instantaneous current at any time will be limited by the power
supply, so it's not as if there will be tens of amps rushing the
battery while the power transistor is turned on.

[Jim Thompson]

On Mon, 06 May 2013 22:16:14 -0400, Uncle Steve <stev...@gmail.com>

How about something like this...

http://www.analog-innovations.com/SED/ChargerForUncleSteve.pdf

[Jasen Betts]

On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:

> I will consider that, but note that Q1 is NPN. What you propose
> suggests I was counting on current-limiting to occur in the wrong
> place.

You can do it like this using the transistors you have.

+18V ----+---+ _+----->|--[Rsense]-----> BAT+
| \ /|
| ----- '3055
| |
+ +
_\| /
------ BC557
|
[100] 0.25W
|
+
/
pwm in |/
---[1K]--| PN2222
|\
_\|
+
|
0V ---+---

> The software feedback loop ought to allow the ideal pulse width to
> 'fly' automatically at the correct setting, assuming the ADC readings
> are reasonably accurate.

> Theoretically, I should also be able to
> detect collapse (?) of the transformer flux if the current draw grows
> too large, which would be a nice bonus.

saturation will show in the primary current much more than anything on
in the secondary circuit and the by detecting it you're measuring the
line voltage more than any other variable.

--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Uncle Steve]

On Tue, May 07, 2013 at 06:43:00AM +0000, Jasen Betts wrote:
> On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:
>
> > I will consider that, but note that Q1 is NPN. What you propose
> > suggests I was counting on current-limiting to occur in the wrong
> > place.
>
> You can do it like this using the transistors you have.
>
> +18V ----+---+ _+----->|--[Rsense]-----> BAT+
> | \ /|
> | ----- '3055
> | |
> + +
> _\| /
> ------ BC557
> |
> [100] 0.25W
> |
> +
> /
> pwm in |/
> ---[1K]--| PN2222
> |\
> _\|
> +
> |
> 0V ---+---

How do you arrive at 100 ohms? I was using 200K because the value is
close to the threshold where it allows something like full power to
flow through the 3055. With 100k or less I was seeing my (cheap)
meter show fluxuating nonsense voltages at the emitter of up to 1500V,
although my scope showed nothing much amiss at lower frequency
settings. I was thinking that the 3055 was somehow generating large
spikes with the rising edge of the pulse, but I did not test it
exhaustively.

> > The software feedback loop ought to allow the ideal pulse width to
> > 'fly' automatically at the correct setting, assuming the ADC readings
> > are reasonably accurate.
>
> > Theoretically, I should also be able to
> > detect collapse (?) of the transformer flux if the current draw grows
> > too large, which would be a nice bonus.
>
> saturation will show in the primary current much more than anything on
> in the secondary circuit and the by detecting it you're measuring the
> line voltage more than any other variable.

That's what I meant. I don't like to be wrong, so it bugs me that I
am not familiar enough with the nomenclature to avoid stepping on my
dick. I probably should say that the PWM will limit the average
/power/ going in the battery, which is what really matters.

As I understand it, volts are sort of like the size of the pipe;
amperes are like the pressure or the rate of flow, and power is the
throughput. Of course it isn't plumbing and there isn't any water.

[Uncle Steve]

I quickly experimented with some lower value resisters and found that
the primary effect of using anything lower than 10K is damage to
either the 2n2222 or the BC557. The failure mode appears to be mainly
permanently shorting collector and emitter, but I observed partially
damaged transistors which would produce 1V at the base of Q1 in the
idle state. Since I've been doing a fair bit of fooling around in the
last 24 hours, it seems I've collected a half-dozen damaged
transistors, which probably contributed to some of the anomalous
readings I have had.

Using fresh parts and 100K between Q3 and Q2, everything is good. The
battery is only drawing 1.6A at this time so I can't easily test the
circuit at higher currents without draining the battery a whole lot.
The ripple at the base of Q1 is still there at 60mVpp which propagates
to the emitter, although I wouldn't see it without the diode. My
guess is that the Sziklai pair is too sensitive for this application,
but I don't really know why or what to do about it. The proximal
sensitivity to mass is another concern, and I don't know whether there
is an internal oscillation occuring that is amplified by a proximal
mass, or whether a proximal mass is triggering the amplification of
power-line hum. An extra .22uF filter capacitor on the 5V rail has no
effect.

[Jamie]

The white wire is the other power wire you need to connect one of the
black wires on the motor to.

THe only reason it is not protected via a wire nut is because that
wire ends up being the low side of the circuit, which should be near
0 volts. But don't take any chances to think it is just a ground wire,
just because it does connect to the ground back to subpanel.

Jamie

[Jamie]

Kind of curious how that LED is handling the current when you only have
a .5 ohm R feeding it? Even if that bias on the base was current
limited, you'll be suppressing the voltage to the battery no more than
what the LED forward voltage is plus the 0.650 drop from the base and
emitter.

As for the noise you maybe seeing, it's possible you are picking that
up because of the wires hanging all over the place. You most likely have
lights with ballast circuits in them, they can generate noise, putting
your hands over the circuit is just using your body to convey the noise
closer.

bjts are grate for acting as R.F. detectors...

Jamie

[George Herold]

I redrew your circuit and tried to make Q2/Q3 look like a Darlington
or Sziklai.. didn't work.

One issue I have with your 'pair' is that the idea of the pair is to
get more current gain. So a transistor with only a small maximum
current drives the bigger transistor. I your case you've got it
backwards. The BC557 has a max Ic of 100mA and the 2n2222 is 500mA.
It also seems like the BC557 wiil driven right near it's max
current... Maybe a beefier pnp is in order?

George H.
>
> http://www.talkingelectronics.com/projects/TheTransistorAmplifier/The...

> representative of Orwellian linguistics at work in the real world.- Hide quoted text -

[Tom Biasi]

On 5/7/2013 8:52 AM, Uncle Steve wrote:

> As I understand it, volts are sort of like the size of the pipe;
> amperes are like the pressure or the rate of flow, and power is the
> throughput. Of course it isn't plumbing and there isn't any water.
>
>
> Regards,
>
> Uncle Steve
>

Even with water, pressure and rate of flow are not the same thing.
Power is the rate of doing work.

[Jim Thompson]

On Tue, 07 May 2013 13:15:10 -0400, Tom Biasi <tomb...@optonline.net>
wrote:

The length of the pipe divided by the diameter is proportionally
equivalent to resistance.

Volts equates to pressure

Current equates to flow rate

[Uncle Steve]

On Mon, May 06, 2013 at 06:44:23PM -0400, Jamie wrote:
> Kind of curious how that LED is handling the current when you only have
> a .5 ohm R feeding it? Even if that bias on the base was current

That's the other R1. The R1 attached to the LED is 2.2K, a mistake I
updated in a later post.

> limited, you'll be suppressing the voltage to the battery no more than
> what the LED forward voltage is plus the 0.650 drop from the base and
> emitter.
>
> As for the noise you maybe seeing, it's possible you are picking that
> up because of the wires hanging all over the place. You most likely have
> lights with ballast circuits in them, they can generate noise, putting
> your hands over the circuit is just using your body to convey the noise
> closer.

I have CFL lights, a stereo, a HDTV, several laptop computers, 4G
phone, oh, and there's a single fluorescent tube in the bathroom. but
the signal I'm seeing at the base of Q1 (NPN) is 60/120 Hz at 70mVpp
(depending on how the scope sees it) on 16V DC, and I'm only seeing
the positive side of the ripple. At power on, the spikes are much
larger and fall over a couple of seconds to the stated amplitude. The
transformer that is powering everything has no regulator, only a
bridge rectifier and a 470uF filter cap. There may be some ripple but
it must be very close to the resolution that my scope LCD can display.
Open-circuit voltage is 26V, which quickly drops to 19V with a 1.6A
load, so I'm wondering if a 7818 regulator would clear things up, but
that would necessarily introduce a different problem.

> bjts are grate for acting as R.F. detectors...

The wires hooking up anything related to Q2/Q3 are no more than four
inches long; everything else (other than the 5V supply rail for the
uC) is attached to the 18V rail. I can tighten things up on the
breadboard a bit, but if RF is getting to the transistors through
their 1" leads there's little I can do about that. ISR that antennas
are sensitive to wavelength as a function of lengths, and VLF antennas
are measured in the hundreds of meters. Obviously IANAEE, and I know
much less about antennas than I do about transistors, which is next to
zilch.

[Tom Biasi]

On 5/7/2013 1:18 PM, Jim Thompson wrote:
> On Tue, 07 May 2013 13:15:10 -0400, Tom Biasi <tomb...@optonline.net>
> wrote:
>
>> On 5/7/2013 8:52 AM, Uncle Steve wrote:
>>
>>> As I understand it, volts are sort of like the size of the pipe;
>>> amperes are like the pressure or the rate of flow, and power is the
>>> throughput. Of course it isn't plumbing and there isn't any water.
>>>
>>>
>>> Regards,
>>>
>>> Uncle Steve
>>>
>> Even with water, pressure and rate of flow are not the same thing.
>> Power is the rate of doing work.
>>
>
> The length of the pipe divided by the diameter is proportionally
> equivalent to resistance.
>
> Volts equates to pressure
>
> Current equates to flow rate
>
> ...Jim Thompson
>

I thought he might look it up himself Jim :-)

[Uncle Steve]

On Tue, May 07, 2013 at 09:43:54AM -0700, George Herold wrote:
> > I don't think so. �The arrangement is described as a Sziklai Pair, and
> > is described at the following URL:
>
> I redrew your circuit and tried to make Q2/Q3 look like a Darlington
> or Sziklai.. didn't work.
>
> One issue I have with your 'pair' is that the idea of the pair is to
> get more current gain. So a transistor with only a small maximum
> current drives the bigger transistor. I your case you've got it
> backwards. The BC557 has a max Ic of 100mA and the 2n2222 is 500mA.
> It also seems like the BC557 wiil driven right near it's max
> current... Maybe a beefier pnp is in order?

Those are just the parts I have on hand, which were selected more or
less at random for the purpose of experimentation. I'm not really
concerned with the fact that the BC557 is 'smaller' than the 2n2222,
only that there is enough juice getting to the base of the MJE3055,
which appears to be true at this point. Before I hooked up the
battery, I used a 36VDC permanent magnet motor and stalled it by hand
to show almost 4A going through the sense resistor.

I suppose you're correct, as the diagrams of Darlington pairs don't
include anything like the 100K I have installed on the Emitter of the
2n2222, and clearly the last BC557 I blew up was due to the greater
driving power of the 2n2222. I see 26mA going out of the PNP.
Perhaps I don't really need the BC557, and could get away with just
the 2n2222 and an appropriate current limiting resistor.

What led to using the PNP transistor was my initial misunderstanding
of how the 3055 worked, and I assumed the base-emitter voltage of 5V
meant that it should have 5V going in to it max, but I failed to
appreciate that I have the 3055 and battery configured in the emitter-
follower configuration. Perhaps I should move the 3055 to the other
side of the battery and try again.

[Jim Thompson]

On Tue, 07 May 2013 13:27:24 -0400, Tom Biasi <tomb...@optonline.net>

Ooooops! Sorry! He is flailing quite a bit. I remember being there
;-)

[Daniel Pitts]

On 5/7/13 5:52 AM, Uncle Steve wrote:
> As I understand it, volts are sort of like the size of the pipe;
> amperes are like the pressure or the rate of flow, and power is the
> throughput. Of course it isn't plumbing and there isn't any water.

Volts are like PSI (pressure).
Amperes are like flow-rate.
Ohms are like 1/(pipe size).
Watts are work performed.

Sans quantum and gravitational effects, electricity is very much like a
electron fluid. There are differences, but it is a useful comparison for
intuitive reasoning.

[Michael A. Terrell]

> The only reason it is not protected via a wire nut is because that

> wire ends up being the low side of the circuit, which should be near
> 0 volts. But don't take any chances to think it is just a ground wire,
> just because it does connect to the ground back to subpanel.

No, it doesn't. It connects to the Neutral, if the circuit is 120
VAC. It may be the other side of a 240 VAC circuit, if it's not wired
to code.

[Michael A. Terrell]

amdx wrote:

>
> On 5/6/2013 11:01 AM, Uncle Steve wrote:
> > Back again for some more abuse.
>

> Where's Phil when somebody really deserves abuse?


Off abusing someone who doesn't deserve it.

[Tom Biasi]

On 5/7/2013 1:46 PM, Jim Thompson wrote:
> On Tue, 07 May 2013 13:27:24 -0400, Tom Biasi <tomb...@optonline.net>
> wrote:
>
>> On 5/7/2013 1:18 PM, Jim Thompson wrote:
>>> On Tue, 07 May 2013 13:15:10 -0400, Tom Biasi <tomb...@optonline.net>
>>> wrote:
>>>
>>>> On 5/7/2013 8:52 AM, Uncle Steve wrote:
>>>>
>>>>> As I understand it, volts are sort of like the size of the pipe;
>>>>> amperes are like the pressure or the rate of flow, and power is the
>>>>> throughput. Of course it isn't plumbing and there isn't any water.
>>>>>
>>>>>
>>>>> Regards,
>>>>>
>>>>> Uncle Steve
>>>>>
>>>> Even with water, pressure and rate of flow are not the same thing.
>>>> Power is the rate of doing work.
>>>>
>>>
>>> The length of the pipe divided by the diameter is proportionally
>>> equivalent to resistance.
>>>
>>> Volts equates to pressure
>>>
>>> Current equates to flow rate
>>>
>>> ...Jim Thompson
>>>
>> I thought he might look it up himself Jim :-)
>
> Ooooops! Sorry! He is flailing quite a bit. I remember being there
> ;-)
>
> ...Jim Thompson
>

No need to apologize. At least you gave a helpful answer and didn't see
the need to "rip him a new one". After all, this is a basic group.

Regards,
Tom

[Jim Thompson]

On Tue, 07 May 2013 14:21:35 -0400, Tom Biasi <tomb...@optonline.net>

I only provide extra assholes to those already exhibiting such
behavior, like our special group of posters here who are
always-dead-wrong, but scream at the top of their lungs that they are
correct, and name-call anyone who dares to suggest a different
scenario.

I'm quite like you, I try to induce thinking. Doesn't always work :-(
And I do remember "being there". In my early teens I really flailed
around trying to make sense of how circuits work ;-)

[Tom Biasi]

On 5/7/2013 2:31 PM, Jim Thompson wrote:
In my early teens I really flailed
> around trying to make sense of how circuits work ;-)
>
> ...Jim Thompson
>

I also. But the most memorable moments were the ones I figured out myself.
No internet then, just a building with some smelly old books.
Regards,
Tom

[Jim Thompson]

On Tue, 07 May 2013 14:39:51 -0400, Tom Biasi <tomb...@optonline.net>
wrote:

My great lurch forward was getting an old GE manual on Germanium
transistors.

My second great lurch forward was getting a technician job in MIT
Building 20. I could solder ;-) And I was simultaneously taking the
right circuit courses.

[Tim Wescott]

On Tue, 07 May 2013 10:18:15 -0700, Jim Thompson wrote:

> On Tue, 07 May 2013 13:15:10 -0400, Tom Biasi <tomb...@optonline.net>
> wrote:
>
>>On 5/7/2013 8:52 AM, Uncle Steve wrote:
>>
>>> As I understand it, volts are sort of like the size of the pipe;
>>> amperes are like the pressure or the rate of flow, and power is the
>>> throughput. Of course it isn't plumbing and there isn't any water.
>>>
>>>
>>> Regards,
>>>
>>> Uncle Steve
>>>
>>Even with water, pressure and rate of flow are not the same thing. Power
>>is the rate of doing work.
>>
>>
> The length of the pipe divided by the diameter is proportionally
> equivalent to resistance.
>
> Volts equates to pressure
>
> Current equates to flow rate

That depends on what system you're using to make a mechanical analog of
an electrical system.

And the head drop through a restriction is generally some constant times
the square of the flow -- quite unlike most electrically resistive
materials, which make for components whose voltage drop is some constant
times current^1.

(Apparently, for decades back at the dawn of electronics, people knew
that the current/voltage relationship through a resistor was

voltage drop = current^x,

but measurement technology was so crude that no one was sure -- even to a
factor of two -- what x was. The prime candidates were 1/2, 1, and 2.
Ohm didn't figure out that resistance happened -- he was the one that
showed that for nearly all materials, x = unity.)

[Rheilly Phoull]

If Uncle is using a micro to control it, why not just control a mosfet
with the PWM output ???

[Jasen Betts]

On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:
> On Tue, May 07, 2013 at 06:43:00AM +0000, Jasen Betts wrote:
>> On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:
>>
>> > I will consider that, but note that Q1 is NPN. What you propose
>> > suggests I was counting on current-limiting to occur in the wrong
>> > place.
>>
>> You can do it like this using the transistors you have.
>>
>> +18V ----+---+ _+----->|--[Rsense]-----> BAT+
>> | \ /|
>> | ----- '3055
>> | |
>> + +
>> _\| /
>> ------ BC557
>> |

change: [1K]

>> |
>> +
>> /
>> pwm in |/

>> --[2K2]--| PN2222

>> |\
>> _\|
>> +
>> |
>> 0V ---+---
>
> How do you arrive at 100 ohms?

it was just a guess, and your're right it's probably bit low for
a BC557 about 18ma in from base would would be better than about
180 so use 1K instead.

as you can see I'm not trying to get precise results transistors
vary but upto a factor of 3 in their gain ratio so ignoring the
small details often doesn't hurt the result.

> I was using 200K because the value is
> close to the threshold where it allows something like full power to
> flow through the 3055.

yeah but i'm not desiging an analogue circuit my goal is to over
bias the transistors so they go into saturation, stay there and
stay cool.

> With 100k or less I was seeing my (cheap)
> meter show fluxuating nonsense voltages at the emitter of up to 1500V,
> although my scope showed nothing much amiss at lower frequency
> settings. I was thinking that the 3055 was somehow generating large
> spikes with the rising edge of the pulse, but I did not test it
> exhaustively.

I woudn't trust a cheap digital meter on a PWM signal, I'd add a
low-pass filter or envelope detector circuit depending on what I
wanted to measure.

[Jasen Betts]

100K seems high, a but BC557 does have quite a lot of gain and can
only handle 100mA, hoever the MJE3066 has much more gain then the
venerable 2N3055 so it hard to predict how strong that transistor need
to be.

A stronger transistor may be better suited there, eg BC327 or
MPSA56, or an even bigger one like BD78 or TIP42

If you want to increase the current just connect a load in parallel
with the battery, eg. a a car headlamp, or other dummy load.

> The ripple at the base of Q1 is still there at 60mVpp which propagates
> to the emitter, although I wouldn't see it without the diode. My
> guess is that the Sziklai pair is too sensitive for this application,
> but I don't really know why or what to do about it. The proximal
> sensitivity to mass is another concern, and I don't know whether there
> is an internal oscillation occuring that is amplified by a proximal
> mass, or whether a proximal mass is triggering the amplification of
> power-line hum. An extra .22uF filter capacitor on the 5V rail has no
> effect.

Hmm, mysterious. You're not pluging the '3055 into a solderless
breadboard, or using long jumper wires to hook this up are you?

[Jasen Betts]

On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:

> On Tue, May 07, 2013 at 09:43:54AM -0700, George Herold wrote:
>> > I don't think so. �The arrangement is described as a Sziklai Pair, and
>> > is described at the following URL:
>>
>> I redrew your circuit and tried to make Q2/Q3 look like a Darlington
>> or Sziklai.. didn't work.
>>
>> One issue I have with your 'pair' is that the idea of the pair is to
>> get more current gain. So a transistor with only a small maximum
>> current drives the bigger transistor. I your case you've got it
>> backwards. The BC557 has a max Ic of 100mA and the 2n2222 is 500mA.
>> It also seems like the BC557 wiil driven right near it's max
>> current... Maybe a beefier pnp is in order?
>
> Those are just the parts I have on hand, which were selected more or
> less at random for the purpose of experimentation. I'm not really
> concerned with the fact that the BC557 is 'smaller' than the 2n2222,
> only that there is enough juice getting to the base of the MJE3055,
> which appears to be true at this point. Before I hooked up the
> battery, I used a 36VDC permanent magnet motor and stalled it by hand
> to show almost 4A going through the sense resistor.

if you want to switch the 3055 by turning on a current to ground (where
the microconttoller is connected) you need to make the top NPN transistor
look like a PNP

The Sziklai pair arrangement does that almost perfectly

> I suppose you're correct, as the diagrams of Darlington pairs don't

> Perhaps I should move the 3055 to the other
> side of the battery and try again.

That would work, but would also make monitoring the battery voltage
using the microcontroller much harder.

[Uncle Steve]

I have the app notes for the LM338 and such, which show simple charger
circuits like that, but the fact of the matter is I have a couple of
3055s and this project is as much about learning some basics as it is
about charging a battery. For my requirements it is easier to use
what I have on hand than try to select among parts that I don't really
understand. If there were a fundamental reason why the 3055 is bad
for this application I might consider a mosfet, but I don't see why I
should bother.

[Uncle Steve]

After figuring out that it seems better in this case to have the
battery on the emitter side of the 3055 (probably doesn't really
matter, but this way seems easier) I rebuilt this configuration with
2.2k on the base of the 2n2222 (to reduce the drain on the uC pin,
perhaps for no good reason) and used 220 ohms on the base of the
BC557, which sets the current into the 3055 base at about 35mA and
10mA for the LED.

> > I was using 200K because the value is
> > close to the threshold where it allows something like full power to
> > flow through the 3055.
>
> yeah but i'm not desiging an analogue circuit my goal is to over
> bias the transistors so they go into saturation, stay there and
> stay cool.

That's the bit I haven't yet figured out. When I understand how to do
that reliably, or at least to requirements, with arbitrary transistors
and without fooling around on a breadboard so much I'll be happier.

> > With 100k or less I was seeing my (cheap)
> > meter show fluxuating nonsense voltages at the emitter of up to 1500V,
> > although my scope showed nothing much amiss at lower frequency
> > settings. I was thinking that the 3055 was somehow generating large
> > spikes with the rising edge of the pulse, but I did not test it
> > exhaustively.
>

> I wouldn't trust a cheap digital meter on a PWM signal, I'd add a

> low-pass filter or envelope detector circuit depending on what I
> wanted to measure.

There's no PWM yet, just a mechanical switch. The weird readings I got
on a couple of occasions were perhaps pathological cases where broken
transistors were doing something stupid.

I have a couple of wrinkles to figure out yet before I start
finalizing the software and begin testing the uC. I probably should
put a LM338 on the p/s to set the voltage to the bulk charge rate,
etc.

[Jim Thompson]

On Wed, 08 May 2013 11:21:13 -0400, Uncle Steve <stev...@gmail.com>

You need a B-E resistor on the 3055. The lack of that probably
accounts for your observed instability.

I'm out this A.M., will post embellishments when I return.

[Uncle Steve]

I have enough gain at the moment, so this is a non-issue until I have
an excuse to make another run to the local electronics retailer.

> If you want to increase the current just connect a load in parallel
> with the battery, eg. a a car headlamp, or other dummy load.

Grin. I have just such a dummy load (25W or so) but it won't tolerate
13.5V (or more) so I'll have to be careful about how it gets hooked
up.

> > The ripple at the base of Q1 is still there at 60mVpp which propagates
> > to the emitter, although I wouldn't see it without the diode. My
> > guess is that the Sziklai pair is too sensitive for this application,
> > but I don't really know why or what to do about it. The proximal
> > sensitivity to mass is another concern, and I don't know whether there
> > is an internal oscillation occuring that is amplified by a proximal
> > mass, or whether a proximal mass is triggering the amplification of
> > power-line hum. An extra .22uF filter capacitor on the 5V rail has no
> > effect.
>
> Hmm, mysterious. You're not pluging the '3055 into a solderless
> breadboard, or using long jumper wires to hook this up are you?

It is a TO-220 package so fits in the breadboard, however I have been
wondering a little about the power rating of the breadboard rails...
The transformer is 55W so I suspect this might not be an entirely
academic issue.

[Uncle Steve]

On Wed, May 08, 2013 at 12:11:13PM +0000, Jasen Betts wrote:
> On 2013-05-07, Uncle Steve <stev...@gmail.com> wrote:
> > On Tue, May 07, 2013 at 09:43:54AM -0700, George Herold wrote:

> >> > I don't think so. ?The arrangement is described as a Sziklai Pair, and

> >> > is described at the following URL:
> >>
> >> I redrew your circuit and tried to make Q2/Q3 look like a Darlington
> >> or Sziklai.. didn't work.
> >>
> >> One issue I have with your 'pair' is that the idea of the pair is to
> >> get more current gain. So a transistor with only a small maximum
> >> current drives the bigger transistor. I your case you've got it
> >> backwards. The BC557 has a max Ic of 100mA and the 2n2222 is 500mA.
> >> It also seems like the BC557 wiil driven right near it's max
> >> current... Maybe a beefier pnp is in order?
> >
> > Those are just the parts I have on hand, which were selected more or
> > less at random for the purpose of experimentation. I'm not really
> > concerned with the fact that the BC557 is 'smaller' than the 2n2222,
> > only that there is enough juice getting to the base of the MJE3055,
> > which appears to be true at this point. Before I hooked up the
> > battery, I used a 36VDC permanent magnet motor and stalled it by hand
> > to show almost 4A going through the sense resistor.
>
> if you want to switch the 3055 by turning on a current to ground (where
> the microconttoller is connected) you need to make the top NPN transistor
> look like a PNP
>
> The Sziklai pair arrangement does that almost perfectly

I first tried that because I was having difficulty getting two 2n2222s
to produce enough gain. I believe I was not setting them up properly,
and is on my to-do list to understand how two NPN stages should work
in this kind of arrangement.

> > I suppose you're correct, as the diagrams of Darlington pairs don't
>
> > Perhaps I should move the 3055 to the other
> > side of the battery and try again.
>
> That would work, but would also make monitoring the battery voltage
> using the microcontroller much harder.

How so? I have a high-impedance resister-divider network hooked up to
the +ve battery terminal and ground, eventually going to a uC pin
configured for ADC. I'd just have to move it to span the battery
terminals instead of +batt and supply ground. The current arrangement
does have the advantage that all three r/d networks will have the same
scale.

[Jim Thompson]

On Wed, 08 May 2013 10:36:21 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>On Wed, May 08, 2013 at 04:44:25PM +0800, Rheilly Phoull wrote:
>> On 07/05/13 10:57, Jim Thompson wrote:

[snip]

>> >
>> >How about something like this...
>> >
>> > http://www.analog-innovations.com/SED/ChargerForUncleSteve.pdf
>> >
>> > ...Jim Thompson
>> >
>> If Uncle is using a micro to control it, why not just control a mosfet
>> with the PWM output ???
>
>I have the app notes for the LM338 and such, which show simple charger
>circuits like that, but the fact of the matter is I have a couple of
>3055s and this project is as much about learning some basics as it is
>about charging a battery. For my requirements it is easier to use
>what I have on hand than try to select among parts that I don't really
>understand. If there were a fundamental reason why the 3055 is bad
>for this application I might consider a mosfet, but I don't see why I
>should bother.
>
>Regards,
>
>Uncle Steve

The 3055 has a minimum beta of 20 at 4 Amps, which you spoke of at one
point in this thread, which means the base current that must be
supplied is 200mA... not a big deal EXCEPT the driving device will see
considerable dissipation.

You ought to go buy the TO-3 version of the LM317 for the circuit I
suggested and avoid the magic smoke ;-)

[Uncle Steve]

I'm starting to appreciate these factors. Yet, after removing the
4004 diode as superfluous and changing the .5 ohm sense resistor to
.1 ohms, I'm seeing 3A output which is pretty much the capacity of the
power supply. The 3055 runs cooler as well; not sure what that means.

Now I have to use an op-amp comparator to measure the current to get
decent resolution.

> You ought to go buy the TO-3 version of the LM317 for the circuit I
> suggested and avoid the magic smoke ;-)

The literature doesn't specify the switching frequency, rise time,
etc. for that part.

[Jim Thompson]

On Wed, 08 May 2013 17:55:36 -0400, Uncle Steve <stev...@gmail.com>

I'm curious why you need to "switch" it? Isn't your only concern the
_average_ current, as determined by the PWM?

All you need is a low-pass R/C between the micro and the base of Q1
(as noted in the text box on the schematic).

I'll run a simulation of that and repost later (under this same link).

http://www.analog-innovations.com/SED/ChargerForUncleSteve.pdf

[Jim Thompson]

And you don't need to measure the current via a high-side OpAmp
kludge, it's calculable from the voltage at the emitter of Q1.

(If you want it to be super precise, just add an OpAmp between your
micro and Q1.)

[Jim Thompson]

On Wed, 08 May 2013 16:01:24 -0700, Jim Thompson

Reposted with those features added...

http://www.analog-innovations.com/SED/ChargerForUncleSteve.pdf

Non-linearity at low end is due to bias current from LM317 adjust pin.
Scaling both R2 and R3, proportionately to lower values, will lower
that break point.

Diode is necessary as a safety in the case where battery is connected,
but 18V supply is set to zero. Diode can be moved in front of LM317
if desired.

[Uncle Steve]

You're probably correct, except the rating of the LM317 is half of
what I need. It's an interesting idea to use PWM to control a voltage
regulator, but it's a completely different approach from what I
intended to build. Perhaps it will be worthwhile to refactor your
design and substitute a LM338, which has the requisite capacity. For
now I think I will fool around with the existing arrangement.

Even at 3A output, the 3055 doesn't appear to be saturated as Vce is
only .9V. I picked up a couple of BC517 which have a beta of 30000
and 1A current capacity. Perhaps that will be more effective than the
BC557 in the pseudo-Sziklai arrangement.

[Jasen Betts]

I would't go over 200mA per contact on an unknown breadboard.
especially where an open circuit or unexpected resistance
could cause a problem.

[Uncle Steve]

Too late! I have already determined that the conducters are capable
of handling 12V at 4A without melting anything. The battery is
another matter with a listed capacity of 180 Cold Cranking Amps, and I
am quite certain a short would cause major damage.

[Jasen Betts]

On 2013-05-09, Uncle Steve <stev...@gmail.com> wrote:
> On Thu, May 09, 2013 at 07:06:21AM +0000, Jasen Betts wrote:
>> On 2013-05-08, Uncle Steve <stev...@gmail.com> wrote:
>> > On Wed, May 08, 2013 at 11:58:50AM +0000, Jasen Betts wrote:
>> >> Hmm, mysterious. You're not pluging the '3055 into a solderless
>> >> breadboard, or using long jumper wires to hook this up are you?
>> >
>> > It is a TO-220 package so fits in the breadboard, however I have been
>> > wondering a little about the power rating of the breadboard rails...
>> > The transformer is 55W so I suspect this might not be an entirely
>> > academic issue.
>> >
>>
>> I would't go over 200mA per contact on an unknown breadboard.
>> especially where an open circuit or unexpected resistance
>> could cause a problem.
>
> Too late! I have already determined that the conducters are capable
> of handling 12V at 4A without melting anything.

not melted anything, but you've destroyed a few transistors in
mysterious circumstances.

If the Q1 (MJE3055) collector contact gets a bit loose all current will
go through Q2 (BC557) and destroy it.

Melt some solder, take the main current path off the breadourd.

> The battery is
> another matter with a listed capacity of 180 Cold Cranking Amps, and I
> am quite certain a short would cause major damage.

100CCA, so it's just a little one (motorcycle?)

[Uncle Steve]

On Fri, May 10, 2013 at 10:47:12AM +0000, Jasen Betts wrote:
> On 2013-05-09, Uncle Steve <stev...@gmail.com> wrote:
> > On Thu, May 09, 2013 at 07:06:21AM +0000, Jasen Betts wrote:
> >> On 2013-05-08, Uncle Steve <stev...@gmail.com> wrote:
> >> > On Wed, May 08, 2013 at 11:58:50AM +0000, Jasen Betts wrote:
> >> >> Hmm, mysterious. You're not pluging the '3055 into a solderless
> >> >> breadboard, or using long jumper wires to hook this up are you?
> >> >
> >> > It is a TO-220 package so fits in the breadboard, however I have been
> >> > wondering a little about the power rating of the breadboard rails...
> >> > The transformer is 55W so I suspect this might not be an entirely
> >> > academic issue.
> >> >
> >>
> >> I would't go over 200mA per contact on an unknown breadboard.
> >> especially where an open circuit or unexpected resistance
> >> could cause a problem.
> >
> > Too late! I have already determined that the conducters are capable
> > of handling 12V at 4A without melting anything.
>
> not melted anything, but you've destroyed a few transistors in
> mysterious circumstances.

Mainly due to bone-headedness.

> If the Q1 (MJE3055) collector contact gets a bit loose all current will
> go through Q2 (BC557) and destroy it.
>
> Melt some solder, take the main current path off the breadourd.

Almost there.

> > The battery is
> > another matter with a listed capacity of 180 Cold Cranking Amps, and I
> > am quite certain a short would cause major damage.
>
> 100CCA, so it's just a little one (motorcycle?)

It's a "lawn and garden" battery. $20.00 on sale, so a good deal even
if it doesn't tolerate actual use all that well. As a backup power
solution it will be used only rarely.

[ehsjr]

I would urge you to follow JT's advice. Build his circuit.

It is easy to add a pass element to get higher current later on.
Here's an example diagram to give you an idea how it's done:


MJ2955
Vin ---+----> ------------------+-----------> Vout
| e\ /c |
[3R] --- |
| | ----- |
+------+---Vin|LM317|Vout---+-------+
| ----- | |
| Adj [240R] |
| | | |
| +----------+ |
| | |
[.22uF] / [.1uF]
| \ |
| 5K /<---+ |
| \ | |
| / | |
| | | |
Gnd ----------+---------+----+-------------+


Current drawn from the 317 causes a voltage drop across the
3 ohm resistor. When that voltage drop is below about .6 volts,
the 2955 conducts no e-c current. When the voltage drop rises
to about .6 volts the 2955 begins to conduct e-c current. The
more current drawn by the load, the greater the e-c current.
The e-c current passes around (not through) the 317 so the 2955
is called a pass element or pass transistor.

You can also do it with your 3055, but you need an inverting
stage to its base. See "High Current Adjustable Regulator"
diagram in the datasheet for the 317 for an example of using
an NPN pass element. They use 3 195's in that diagram, but
you need only the single 3055.

> It's an interesting idea to use PWM to control a voltage
> regulator, but it's a completely different approach from what I
> intended to build.

In reading your various posts it seems clear to me that you are
expending a lot of effort and have a lot of interest in this, which
is all to the good. But I also see that you are speeding by some
points where you could benefit by working to understand them,
rather than passing them by - which is what prompted me to reply.

> Perhaps it will be worthwhile to refactor your
> design and substitute a LM338, which has the requisite capacity.

No perhaps about it, it is definitely worthwhile. The earlier
part of my reply suggests how you can do it with parts on
hand, then later on add a pass element, or, as you mention,
substitute a 338.

> For
> now I think I will fool around with the existing arrangement.
>
> Even at 3A output, the 3055 doesn't appear to be saturated as Vce is
> only .9V. I picked up a couple of BC517 which have a beta of 30000
> and 1A current capacity. Perhaps that will be more effective than the
> BC557 in the pseudo-Sziklai arrangement.
>
>

Well, you may get it to work, but you won't learn why
it does, or why the previous attempts didn't. It is
my impression that you are leap frogging some of the
basics. Sometimes throwing bigger/better/stronger parts
at a problem is not in your best interests.

Ed


>
> Regards,
>
> Uncle Steve
>

[Uncle Steve]

Actually, I recalled seeing this circuit in the app notes, but only
after I replied.

> Current drawn from the 317 causes a voltage drop across the
> 3 ohm resistor. When that voltage drop is below about .6 volts,
> the 2955 conducts no e-c current. When the voltage drop rises
> to about .6 volts the 2955 begins to conduct e-c current. The
> more current drawn by the load, the greater the e-c current.
> The e-c current passes around (not through) the 317 so the 2955
> is called a pass element or pass transistor.
>
> You can also do it with your 3055, but you need an inverting
> stage to its base. See "High Current Adjustable Regulator"
> diagram in the datasheet for the 317 for an example of using
> an NPN pass element. They use 3 195's in that diagram, but
> you need only the single 3055.

That's the one.

> >It's an interesting idea to use PWM to control a voltage
> >regulator, but it's a completely different approach from what I
> >intended to build.
>
> In reading your various posts it seems clear to me that you are
> expending a lot of effort and have a lot of interest in this, which
> is all to the good. But I also see that you are speeding by some
> points where you could benefit by working to understand them,
> rather than passing them by - which is what prompted me to reply.

That's the understatement of the week. The problem is there are too
many points, here and in the various bits of literature I've read, to
study in any reasonable length of time.

> >Perhaps it will be worthwhile to refactor your
> >design and substitute a LM338, which has the requisite capacity.
>
> No perhaps about it, it is definitely worthwhile. The earlier
> part of my reply suggests how you can do it with parts on
> hand, then later on add a pass element, or, as you mention,
> substitute a 338.
>
> >For
> >now I think I will fool around with the existing arrangement.
> >
> >Even at 3A output, the 3055 doesn't appear to be saturated as Vce is
> >only .9V. I picked up a couple of BC517 which have a beta of 30000
> >and 1A current capacity. Perhaps that will be more effective than the
> >BC557 in the pseudo-Sziklai arrangement.
> >
> >
>
> Well, you may get it to work, but you won't learn why
> it does, or why the previous attempts didn't. It is
> my impression that you are leap frogging some of the
> basics. Sometimes throwing bigger/better/stronger parts
> at a problem is not in your best interests.

I'm more interested in using the different parts to see how they
affect the whole thing. I think I am at the stage where it is
becoming practical to do that sort of experimentation.

[Jim Thompson]

On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>Back again for some more abuse.
>
>I'm building a 12V battery charger that will be controlled by a small
>low-power microcontroller. I've not yet hooked up the
>microcontroller, but most of the code is written and I'm trying to
>finalize the charger electronics before I hook it up.
>
[snip]

Remembered where I had stashed some ancient data...

http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf

These are the TC curves provided to me by GM and Ford back in the day
when I designed alternator regulators.

Your regulator should approximate such a TC if you want to hold a
reasonable charge on your lead-acid battery.

What information do you actually need fed back to your
microcontroller?

[Uncle Steve]

On Fri, May 10, 2013 at 07:27:39PM -0700, Jim Thompson wrote:
> On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >Back again for some more abuse.
> >
> >I'm building a 12V battery charger that will be controlled by a small
> >low-power microcontroller. I've not yet hooked up the
> >microcontroller, but most of the code is written and I'm trying to
> >finalize the charger electronics before I hook it up.
> >
> [snip]
>
> Remembered where I had stashed some ancient data...
>
> http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf

What, no NDA? Holy crap! I don't want to have to install plumbing to
keep the water level above the top of the plates.

> These are the TC curves provided to me by GM and Ford back in the day
> when I designed alternator regulators.
>
> Your regulator should approximate such a TC if you want to hold a
> reasonable charge on your lead-acid battery.

I suspect the thing will charge reasonably quickly with a fixed-
voltage set to the float charge level, but I have numbers from 13.1V
to 13.5V for the float from different sources. It may depend a little
on the battery. For EOC float, it may be easier to specify 50-150mA
or so charge current.

> What information do you actually need fed back to your
> microcontroller?

Supply voltage, battery voltage, sense resistor voltage, battery
temperature. It would be nice to have load voltage and load current
as well, but I could do without if I had to since my NAS is a static
load.

Serial I/O is one pin since as I'm only doing TX. The ATtiny85 I was
trying out has 5 I/O pins if I keep _RESET_, so I'll have to multiplex
all those measurements on one A/D channel, which actually simplifies
the software a lot. Should be doable, assuming I can make the
electronics work properly. I don't know if any extra safety devices
or sensors are recommended, but with three select bits available,
there are options. Sound reasonable?

[Jim Thompson]

On Fri, 10 May 2013 23:14:42 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Fri, May 10, 2013 at 07:27:39PM -0700, Jim Thompson wrote:
>> On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> >Back again for some more abuse.
>> >
>> >I'm building a 12V battery charger that will be controlled by a small
>> >low-power microcontroller. I've not yet hooked up the
>> >microcontroller, but most of the code is written and I'm trying to
>> >finalize the charger electronics before I hook it up.
>> >
>> [snip]
>>
>> Remembered where I had stashed some ancient data...
>>
>> http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf
>
>What, no NDA? Holy crap!

No NDA? You missed the dates. This was 46+ years ago ;-)

"Jerry" Stenklyft was a nice engineer/friend from Anderson, Indiana,
who, while visiting Motorola, would come over to my house, help me lay
floor tile, then have dinner with us ;-)

He died in 2004 at age 70.

>I don't want to have to install plumbing to
>keep the water level above the top of the plates.

That's what following the TC curve does for you... minimizes water
usage.

BTW, the flattening at low and high temperatures is NOT lead-acid
physics, it's to keep from burning out head lights when cold, and to
minimize dimming when hot. A straight curve is quite adequate for
your purposes.

(My ignition system designs work down to 3V cranking voltage ;-)

>
>> These are the TC curves provided to me by GM and Ford back in the day
>> when I designed alternator regulators.
>>
>> Your regulator should approximate such a TC if you want to hold a
>> reasonable charge on your lead-acid battery.
>
>I suspect the thing will charge reasonably quickly with a fixed-
>voltage set to the float charge level, but I have numbers from 13.1V
>to 13.5V for the float from different sources. It may depend a little
>on the battery. For EOC float, it may be easier to specify 50-150mA
>or so charge current.

You're in for a surprise... holding at 13.2V will give you a weenie
capability charge.

>
>> What information do you actually need fed back to your
>> microcontroller?
>
>Supply voltage, battery voltage, sense resistor voltage, battery
>temperature. It would be nice to have load voltage and load current
>as well, but I could do without if I had to since my NAS is a static
>load.

I still don't understand what you are trying accomplish. Charging a
lead acid battery to a proper level is downright trivial with
stand-alone simple-minded circuitry. How do you plan to measure
battery temperature?

>
>Serial I/O is one pin since as I'm only doing TX. The ATtiny85 I was
>trying out has 5 I/O pins if I keep _RESET_, so I'll have to multiplex
>all those measurements on one A/D channel, which actually simplifies
>the software a lot. Should be doable, assuming I can make the
>electronics work properly. I don't know if any extra safety devices
>or sensors are recommended, but with three select bits available,
>there are options. Sound reasonable?

I don't speak micros... I hire that out. I have a long-time buddy in
Columbus, OH, who adds any needed digital and bus needs (SPI, I2C,
CAN, etc.) to my analog chips and he also does my layouts. He has a
Master's from Ohio State and is a whiz at Verilog and VHDL. (Let me
know if you have such needs, and I'll provide contact information.)

>
>
>Regards,
>
>Uncle Steve

[Uncle Steve]

On Sat, May 11, 2013 at 09:19:40AM -0700, Jim Thompson wrote:
> On Fri, 10 May 2013 23:14:42 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >On Fri, May 10, 2013 at 07:27:39PM -0700, Jim Thompson wrote:
> >> On Mon, 06 May 2013 12:01:44 -0400, Uncle Steve <stev...@gmail.com>
> >> wrote:
> >>
> >> >Back again for some more abuse.
> >> >
> >> >I'm building a 12V battery charger that will be controlled by a small
> >> >low-power microcontroller. I've not yet hooked up the
> >> >microcontroller, but most of the code is written and I'm trying to
> >> >finalize the charger electronics before I hook it up.
> >> >
> >> [snip]
> >>
> >> Remembered where I had stashed some ancient data...
> >>
> >> http://www.analog-innovations.com/SED/AlternatorRegulatorTC.pdf
> >
> >What, no NDA? Holy crap!
>
> No NDA? You missed the dates. This was 46+ years ago ;-)

The lawyers have been busy since that time. 46 years ago farmers
could buy dynamite to remove tree stumps on their property. Kids
these days would find "Rocket Ship Galileo" utterly alien. Building
rocket motors? Radar? Preposterous.

We're all so much safer now that all that icky science and engineering
is restricted to licensed and regulated corporate facilities.

> "Jerry" Stenklyft was a nice engineer/friend from Anderson, Indiana,
> who, while visiting Motorola, would come over to my house, help me lay
> floor tile, then have dinner with us ;-)
>
> He died in 2004 at age 70.

Condolences. I suppose he didn't have his head frozen to be stored
and tended to by ultra-reliable robots at some autonomous cryogenic
facility in the far North.

> >I don't want to have to install plumbing to
> >keep the water level above the top of the plates.
>
> That's what following the TC curve does for you... minimizes water
> usage.
>
> BTW, the flattening at low and high temperatures is NOT lead-acid
> physics, it's to keep from burning out head lights when cold, and to
> minimize dimming when hot. A straight curve is quite adequate for
> your purposes.

I should think so. My reading on the matter tells me the key to
battery-longevity are gentle charge/discharge curves, minimizing
temperature excursions, and of course keeping them fully charged.

> (My ignition system designs work down to 3V cranking voltage ;-)

Heh. That's a lot of amps.

> >> These are the TC curves provided to me by GM and Ford back in the day
> >> when I designed alternator regulators.
> >>
> >> Your regulator should approximate such a TC if you want to hold a
> >> reasonable charge on your lead-acid battery.
> >
> >I suspect the thing will charge reasonably quickly with a fixed-
> >voltage set to the float charge level, but I have numbers from 13.1V
> >to 13.5V for the float from different sources. It may depend a little
> >on the battery. For EOC float, it may be easier to specify 50-150mA
> >or so charge current.
>
> You're in for a surprise... holding at 13.2V will give you a weenie
> capability charge.

I haven't decided on a charge voltage yet. Once I sort of have the
electronics where I want them, I'll run a discharge/charge cycle and
watch what actually occurs. If I start with 15V supply and PWM, the
battery voltage can be set to whatever is appropriate given battery
state-of-charge. I'm ready for surprises.

> >> What information do you actually need fed back to your
> >> microcontroller?
> >
> >Supply voltage, battery voltage, sense resistor voltage, battery
> >temperature. It would be nice to have load voltage and load current
> >as well, but I could do without if I had to since my NAS is a static
> >load.
>
> I still don't understand what you are trying accomplish. Charging a
> lead acid battery to a proper level is downright trivial with
> stand-alone simple-minded circuitry. How do you plan to measure
> battery temperature?

I'll tape a thermistor to the case, or maybe I'll use some glue.

This is a good first project with the microcontroller precisely
because it is so trivial. I could go out and buy a small UPS for less
than a hundred bucks but where's the fun in that? I'll probably write
it up afterwards, so you'll be able to see what it looks like then.

> >Serial I/O is one pin since as I'm only doing TX. The ATtiny85 I was
> >trying out has 5 I/O pins if I keep _RESET_, so I'll have to multiplex
> >all those measurements on one A/D channel, which actually simplifies
> >the software a lot. Should be doable, assuming I can make the
> >electronics work properly. I don't know if any extra safety devices
> >or sensors are recommended, but with three select bits available,
> >there are options. Sound reasonable?
>
> I don't speak micros... I hire that out. I have a long-time buddy in
> Columbus, OH, who adds any needed digital and bus needs (SPI, I2C,
> CAN, etc.) to my analog chips and he also does my layouts. He has a
> Master's from Ohio State and is a whiz at Verilog and VHDL. (Let me
> know if you have such needs, and I'll provide contact information.)

I'm just getting started with microcontrollers, but I already know
what I'm doing in so far as programming is concerned. It was
surprisingly easy to do the serial code; the Atmel part is full of
features that make everything super-easy without a lot of external
electronics.

[Jim Thompson]

On Sat, 11 May 2013 13:19:33 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Sat, May 11, 2013 at 09:19:40AM -0700, Jim Thompson wrote:
>> On Fri, 10 May 2013 23:14:42 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>

[snip]

>
>> (My ignition system designs work down to 3V cranking voltage ;-)
>
>Heh. That's a lot of amps.

Think Detroit, -20�F, parked outside overnight. I've observed 4V
myself :-)

I'd still go a buck regulator (with a limited current capability), and
fudge in the TC curve.

[Uncle Steve]

On Sat, May 11, 2013 at 10:46:47AM -0700, Jim Thompson wrote:
> On Sat, 11 May 2013 13:19:33 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >On Sat, May 11, 2013 at 09:19:40AM -0700, Jim Thompson wrote:
> >> On Fri, 10 May 2013 23:14:42 -0400, Uncle Steve <stev...@gmail.com>
> >> wrote:
> >>
> [snip]
> >
> >> (My ignition system designs work down to 3V cranking voltage ;-)
> >
> >Heh. That's a lot of amps.
>
> Think Detroit, -20°F, parked outside overnight. I've observed 4V
> myself :-)

Oh, you were referring to the battery chemistry hysteresis. I would
never have imagined that car batteries dropped out that much.

This Atmel application note describes a development board using such a
circuit. I suppose a buck regulator is common in these applications.

http://www.atmel.com/Images/doc8088.pdf

[Jim Thompson]

On Sat, 11 May 2013 14:19:20 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Sat, May 11, 2013 at 10:46:47AM -0700, Jim Thompson wrote:
>> On Sat, 11 May 2013 13:19:33 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> >On Sat, May 11, 2013 at 09:19:40AM -0700, Jim Thompson wrote:
>> >> On Fri, 10 May 2013 23:14:42 -0400, Uncle Steve <stev...@gmail.com>
>> >> wrote:
>> >>
>> [snip]
>> >
>> >> (My ignition system designs work down to 3V cranking voltage ;-)
>> >
>> >Heh. That's a lot of amps.
>>
>> Think Detroit, -20�F, parked outside overnight. I've observed 4V
>> myself :-)

No, no! While cranking a cold engine.

Yep. Just replace the output bank of capacitors with your battery.

>
>
>
>Regards,
>
>Uncle Steve