Transistors

[Uncle Steve]

Ok, this is a question that is not so battery-charger specific, but
is obviously related.

So here's a circuit fragment:

18V +----+--------__^------/\/\/-----------+
| 2n3055| 0R5 |
| | 5W /
| | \ 5R10W
| | /
|_______|> \
| |_ 2n2906 |
| | |
| | |
| | |
+------__^ 2n2222 |
| |
/ |
1M \ |
/ |
\ |
| |
| |
\ SW |
\ |
| |
5V +-----------+ |
|
GND +-----------+-------------------------+

So this circuit shows ~38mA going in to the base of the 2n3055, and
~13.9V across the 5 ohm resistor. It gets warm quickly.

If I change the 2n3055 for a TIP147 (PNP, beta 1k) and make the
obvious changes to the 2n2906 to make it work, there is ~80mA current
at the base of the TIP147, and ~14.1V across the 10W resistor.

WTF, over?

Needless to say I am happy that my $14.00 DVM has a transistor tester,
because with 10k feeding the 2n2222 the 2n2906 doesn't last very long
with a TIP147 in-circuit. Of course, in that configuration the base
of a 2n3055 still shows 38mA. These results suggest that the
base-emitter current of the 2n3055 cannot go any higher without a
larger power supply, but that is supposition that the 2n3055 somehow
limits the base current to some proportionate ratio to the collector-
emitter current available to it. Is that in any way a reasonable
explanation for what is occurring here?



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.

[Phil Allison]

"Uncle Steve"

> Of course, in that configuration the base
> of a 2n3055 still shows 38mA. These results suggest that the
> base-emitter current of the 2n3055 cannot go any higher without a
> larger power supply, but that is supposition that the 2n3055 somehow
> limits the base current to some proportionate ratio to the collector-
> emitter current available to it. Is that in any way a reasonable
> explanation for what is occurring here?
>

** Yep.

The B-E current is related to the C-E current by a ratio called "beta" or
"Hfe". Beta is not however a fixed number, it varies over the range of
possible collector currents.

For a 2N3055 over the range of 0.1 amps to 3 amps, the number is fairly
constant at about 50 to 100 - depending on the particular device. The value
falls at lower and higher currents PLUS when the C-E voltage is very low.

See figure 3 " DC Current Gain, 2N3055 NPN "

http://www.onsemi.com/pub_link/Collateral/2N3055-D.PDF

All the graphs are worth study, as this is how most power transistors
behave.



... Phil

[Jim Thompson]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

Draw it up real purty, so you can tell PNP's from NPN's and can see
that current can only flow OUT of the NPN emitter and INTO a PNP
emitter... and DO THE MATH ;-)

...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.

[Tim Wescott]

OK. First, the drawing came through mangled. I hope I reconstituted it
correctly.

Second, the way you have it drawn, the 2N2222 isn't going to act like a
transistor. If you _really_ did it as drawn, the BE junction of the
2N2222 will act like a zener diode at around 6V, because that's just what
little transistors do when you challenge their BE junctions with too much
voltage.

Third, you've drawn the 2N2906 as an NPN, but my references says it's a
PNP.

Frankly, I don't see how this circuit can do _anything_, which leads me
to believe that either it is not drawn as built, or there's some more
zener breakdown or other oddball things happening.

Like JT said: you've got to put current _into_ the base of an NPN, and
pull current _out_ of the base of a PNP for them to act properly. You
don't seem to be making that happen.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Jasen Betts]

On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:
> Ok, this is a question that is not so battery-charger specific, but
> is obviously related.

if you want to use a microcontroller you have to design
the low side switch part so that current flows out of
the 5V node, not into it.

so dont do this:

> | |
> | |
> \ SW |
> \ |
> | |
> 5V +-----------+ |
> |
> GND +-----------+-------------------------+

do either this

|
|/
5V--[10K]--|
|>|
|
|
\ sw
\
|
------------+----------


or this:

sw |
/ |/
5V--/ --[10K]--|
|>|
|
|
------------+-------


--
⚂⚃ 100% natural

[Jasen Betts]

On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:

> Ok, this is a question that is not so battery-charger specific, but
> is obviously related.

If you want to use a microcontroller you have to design

the low side switch part so that current flows out of
the 5V node, not into it.

so dont do this:

> | |
> | |

> \ SW |
> \ |
> | |
> 5V +-----------+ |
> |
> GND +-----------+-------------------------+

do either this

|
|/
5V--[10K]--|
|>|
|
|
\ sw
\
|
------------+----------


or this:

sw |
/ |/
5V--/ --[10K]--|
|>|
|
|
------------+-------

if you wat to be sure put in a diode from the switch output to +5
, a microcontroller will have that internally.
it also has a diode from ground.

like this:

|
|
|/
5V--+--[10K]--|
| |>|
| |
`----|<-----+
|
.---->|-----+
| |
| \ sw
| \
| |
+-----------+----------


or this:
|
|
/ |/
5V-+-/ -+-[10K]--|
| | |>|
`-|<-+-|<-. |
| |
--------+-----+-------


the followig has no chance of working, because
once you put the protection diodes in it becomes
obvious that the current from the high side
switch components will just flow through the
top diode

|
.--|<---+ |
| | |
| \ SW |
| \ |
| | |
5V +---+-------+---|<---. |
| |
GND +--------------------+----------------+

infact the oscillations and other wierd behavior you
have seen may be due to your 5V supply being back fed.

--
⚂⚃ 100% natural

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

[Uncle Steve]

I see the significance of these curves a little better now, and it's
probably somewhat unreasonable to compare a BJT with a Darlington.
The interesting thing is that the behaviour of the BJT seems to be
more 'reasonable' in this application since it protects the previous
stage.

The next step for me is to figure out how to predict these factors to
reduce the amount of fooling around I am still doing. Nevertheless,
there is nothing like making measurements to show what is in fact
going on with these devices.

[Phil Allison]

"Uncle Steve"

>
> Nevertheless,
> there is nothing like making measurements to show what is in fact
> going on with these devices.

** Give this man a Kewpie doll.



... Phil

[Uncle Steve]

On Thu, May 09, 2013 at 07:11:43PM -0700, Jim Thompson wrote:
> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >Ok, this is a question that is not so battery-charger specific, but
> >is obviously related.
> >
> >So here's a circuit fragment:
> >

> >18V +----+--------__^------/\/\/--------+

> > | 2n3055| 0R5 |
> > | | 5W /
> > | | \ 5R10W
> > | | /

> > | | \
> > +------__v 2n2906 |
> > | |
> > | |
> > 2n2222 +---| |
> > | |>----+ |
> > | | |
> > / | |
> > 1M \ | |
> > / | |
> > \ | |
> > | | |
> > | | |
> > \ SW | |
> > \ | |
> > | | |
> >5V +-----+ | |
> > | |
> >GND +---------------+------------------+

> >
> >So this circuit shows ~38mA going in to the base of the 2n3055, and
> >~13.9V across the 5 ohm resistor. It gets warm quickly.
> >
> >If I change the 2n3055 for a TIP147 (PNP, beta 1k) and make the
> >obvious changes to the 2n2906 to make it work, there is ~80mA current
> >at the base of the TIP147, and ~14.1V across the 10W resistor.
> >
> >WTF, over?
> >
> >Needless to say I am happy that my $14.00 DVM has a transistor tester,
> >because with 10k feeding the 2n2222 the 2n2906 doesn't last very long
> >with a TIP147 in-circuit. Of course, in that configuration the base
> >of a 2n3055 still shows 38mA. These results suggest that the
> >base-emitter current of the 2n3055 cannot go any higher without a
> >larger power supply, but that is supposition that the 2n3055 somehow
> >limits the base current to some proportionate ratio to the collector-
> >emitter current available to it. Is that in any way a reasonable
> >explanation for what is occurring here?
>
>

> Draw it up real purty, so you can tell PNP's from NPN's and can see
> that current can only flow OUT of the NPN emitter and INTO a PNP
> emitter... and DO THE MATH ;-)

Sorry, I was tired and really mangled the schematic. Fixed above.

[Uncle Steve]

On Thu, May 09, 2013 at 10:57:58PM -0500, Tim Wescott wrote:
>
> OK. First, the drawing came through mangled. I hope I reconstituted it
> correctly.

No, this is actually it:


18V +----+--------__^------/\/\/--------+

| 2n3055| 0R5 |
| | 5W /
| | \ 5R10W
| | /

| | \
+------__v 2n2906 |
| |
| |
2n2222 +---| |
| |>----+ |
| | |

/ | |
1M \ | |
/ | |
\ | |
| | |
| | |
\ SW | |
\ | |
| | |
5V +-----+ | |
| |
GND +---------------+------------------+

> Second, the way you have it drawn, the 2N2222 isn't going to act like a
> transistor. If you _really_ did it as drawn, the BE junction of the
> 2N2222 will act like a zener diode at around 6V, because that's just what
> little transistors do when you challenge their BE junctions with too much
> voltage.
>
> Third, you've drawn the 2N2906 as an NPN, but my references says it's a
> PNP.
>
> Frankly, I don't see how this circuit can do _anything_, which leads me
> to believe that either it is not drawn as built, or there's some more
> zener breakdown or other oddball things happening.
>
> Like JT said: you've got to put current _into_ the base of an NPN, and
> pull current _out_ of the base of a PNP for them to act properly. You
> don't seem to be making that happen.

My brain isn't trained to recognize the symbols and circuits with any
fluency yet, so when I did the original drawing while tired, it didn't
register. Apologies for the confusion.

When I make silly errors like that when writing code it's also vastly
amusing.

[Uncle Steve]

On Fri, May 10, 2013 at 11:13:48AM +0000, Jasen Betts wrote:
> On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:
> > Ok, this is a question that is not so battery-charger specific, but
> > is obviously related.
>
> If you want to use a microcontroller you have to design
> the low side switch part so that current flows out of
> the 5V node, not into it.
>
> so dont do this:
>
> > | |
> > | |
> > \ SW |
> > \ |
> > | |
> > 5V +-----------+ |
> > |
> > GND +-----------+-------------------------+

When I actually hook this up to a microcontroller the 5V will be the
output from the pin designated for PWM, assuming I stick with that
strategy. As I said earlier, the switch is there to simulate a
microcontroller.

> do either this
>
> |
> |/
> 5V--[10K]--|
> |>|
> |
> |
> \ sw
> \
> |
> ------------+----------
>
>
> or this:
>
> sw |
> / |/
> 5V--/ --[10K]--|
> |>|
> |
> |
> ------------+-------
>
>
> if you wat to be sure put in a diode from the switch output to +5
> , a microcontroller will have that internally.
> it also has a diode from ground.
>
> like this:
>
> |
> |
> |/
> 5V--+--[10K]--|
> | |>|
> | |
> `----|<-----+
> |
> .---->|-----+
> | |
> | \ sw
> | \
> | |
> +-----------+----------

Not sure what the purpose of the second diode is there. Doesn't look
like it can do much of anything.

> or this:
> |
> |
> / |/
> 5V-+-/ -+-[10K]--|
> | | |>|
> `-|<-+-|<-. |
> | |
> --------+-----+-------
>
>
> the followig has no chance of working, because
> once you put the protection diodes in it becomes
> obvious that the current from the high side
> switch components will just flow through the
> top diode
>
> |
> .--|<---+ |
> | | |
> | \ SW |
> | \ |
> | | |
> 5V +---+-------+---|<---. |
> | |
> GND +--------------------+----------------+
>
> infact the oscillations and other wierd behavior you
> have seen may be due to your 5V supply being back fed.

It's hard to say. When I was using a motor as a load there were wierd
things happening all over the place, but I was also making stupid
mistakes and damaging small signal transistors in non-obvious ways.

[Uncle Steve]

I've always wanted a Kewpie doll.

It's interesting that all of the literature and web-pages I've read so
far have failed to impart an accurate sense of what these things do.
I don't know whether that is because the learning curve is so steep,
or whether the terminology is truly confusing to the uninitiated. I
think it might be easier to understand electronics if circuit diagrams
represented electron flow and electron charge potential more
obviously. After all it's the electrons moving around that gets
work done, correct?

[John Fields]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

---
Version 4
SHEET 1 880 708
WIRE -16 0 -192 0
WIRE 96 0 -16 0
WIRE 176 0 96 0
WIRE 320 0 272 0
WIRE -16 64 -16 0
WIRE 96 112 96 0
WIRE 224 112 224 64
WIRE 224 112 192 112
WIRE -16 208 -16 144
WIRE 144 208 144 176
WIRE 144 208 -16 208
WIRE 144 240 144 208
WIRE 320 272 320 0
WIRE 144 352 144 320
WIRE -32 400 -80 400
WIRE 80 400 48 400
WIRE -192 480 -192 0
WIRE -80 480 -80 400
WIRE -192 624 -192 560
WIRE -80 624 -80 560
WIRE -80 624 -192 624
WIRE 144 624 144 448
WIRE 144 624 -80 624
WIRE 320 624 320 352
WIRE 320 624 144 624
WIRE -192 688 -192 624
FLAG -192 688 0
SYMBOL npn 176 64 R270
WINDOW 0 68 29 VRight 2
WINDOW 3 99 3 VRight 2
SYMATTR InstName Q1
SYMATTR Value 2N3055
SYMBOL npn 80 352 R0
SYMATTR InstName Q3
SYMATTR Value 2N2222
SYMBOL res 304 256 R0
SYMATTR InstName R1
SYMATTR Value 5.5
SYMBOL voltage -192 464 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 18
SYMBOL voltage -80 464 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 100n 100n 1 2)
SYMBOL res 64 384 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 2.7k
SYMBOL pnp 192 176 M270
WINDOW 0 61 61 VLeft 2
WINDOW 3 92 86 VLeft 2
SYMATTR InstName Q2
SYMATTR Value 2N2907
SYMBOL res -32 48 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res 128 224 R0
SYMATTR InstName R4
SYMATTR Value 1k
TEXT -176 656 Left 2 !.tran 5

--
JF

[Jim Thompson]

On Fri, 10 May 2013 08:58:49 -0400, Uncle Steve <stev...@gmail.com>

PNP collector must be more negative than its emitter... swap emitter
and collector on the 2N2906.

But you're still in "fry" land :-(

WHAT is the OBJECT of your endeavor? Trickle charging a back-up
battery?

[Jim Thompson]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>Ok, this is a question that is not so battery-charger specific, but
>is obviously related.
>

[snip]

>but that is supposition that the 2n3055 somehow
>limits the base current to some proportionate ratio to the collector-
>emitter current available to it. Is that in any way a reasonable
>explanation for what is occurring here?

Nope, that is your main conceptual error.

>
>
>
>Regards,
>
>Uncle Steve

[Uncle Steve]

On Fri, May 10, 2013 at 07:38:44AM -0700, Jim Thompson wrote:
> On Fri, 10 May 2013 08:58:49 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >On Thu, May 09, 2013 at 07:11:43PM -0700, Jim Thompson wrote:
> >> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> >> wrote:
> >>
> >> >Ok, this is a question that is not so battery-charger specific, but
> >> >is obviously related.
> >> >
> >> >So here's a circuit fragment:
> >> >
> >> >18V +----+--------__^------/\/\/--------+
> >> > | 2n3055| 0R5 |
> >> > | | 5W /
> >> > | | \ 5R10W
> >> > | | /
> >> > | | \

> >> > +------v_| 2n2906 |

> >> > | |
> >> > | |
> >> > 2n2222 +---| |
> >> > | |>----+ |
> >> > | | |
> >> > / | |
> >> > 1M \ | |
> >> > / | |
> >> > \ | |
> >> > | | |
> >> > | | |
> >> > \ SW | |
> >> > \ | |
> >> > | | |
> >> >5V +-----+ | |
> >> > | |
> >> >GND +---------------+------------------+
> >> >

> PNP collector must be more negative than its emitter... swap emitter
> and collector on the 2N2906.

I wish I could run that fancy ASCII schematic CAD tool, but I don't
use Windows.

> But you're still in "fry" land :-(
>
> WHAT is the OBJECT of your endeavor? Trickle charging a back-up
> battery?

I wouldn't characterize 3A as a trickle, but in essence I hope to end
up with a battery charger that will charge the battery while it is
under a moderate 20W+ load. I have bit-banged serial out on the
microcontroller, so it will log status to the load device that way,
and inform it when mains power fails.

It is a learning exercise, but I hope to end up with something
vaguely resembling a UPS when all is said and done.

[Phil Hobbs]

On 5/10/2013 10:22 AM, Uncle Steve wrote:
> On Fri, May 10, 2013 at 11:00:13PM +1000, Phil Allison wrote:
>>
>> "Uncle Steve"
>>>
>>> Nevertheless,
>>> there is nothing like making measurements to show what is in fact
>>> going on with these devices.
>>
>>
>> ** Give this man a Kewpie doll.
>
> I've always wanted a Kewpie doll.
>
> It's interesting that all of the literature and web-pages I've read so
> far have failed to impart an accurate sense of what these things do.
> I don't know whether that is because the learning curve is so steep,
> or whether the terminology is truly confusing to the uninitiated. I
> think it might be easier to understand electronics if circuit diagrams
> represented electron flow and electron charge potential more
> obviously. After all it's the electrons moving around that gets
> work done, correct?
>

Except in PNPs. ;)

Seriously, once current starts to be an intuitive concept for you,
you'll rarely need to think about electrons at all.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

[John Fields]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>Needless to say I am happy that my $14.00 DVM has a transistor tester,
>because with 10k feeding the 2n2222 the 2n2906 doesn't last very long
>with a TIP147 in-circuit. Of course, in that configuration the base
>of a 2n3055 still shows 38mA. These results suggest that the
>base-emitter current of the 2n3055 cannot go any higher without a
>larger power supply, but that is supposition that the 2n3055 somehow
>limits the base current to some proportionate ratio to the collector-
>emitter current available to it. Is that in any way a reasonable
>explanation for what is occurring here?

---
No.

In reality it's the base-to-emitter current which controls the
collector-to-emitter current.

The ratio of Ice to Ibe is called 'beta' or 'Hfe' and describes the
current gain of the device.

From the curves you have, you can see that Hfe varies widely with
collector current and temperature, and also from device to device.

--
JF

[John Fields]

On Fri, 10 May 2013 10:59:14 -0400, Uncle Steve <stev...@gmail.com>

---
You might try changing your format.

Here's an example; it's the ASCIImatic for the LTspice circuit list I
posted for you earlier: (View using a fixed-pitch font.)


+18V-----------+-----+-C E---------+
| | B 2N3055 |
| | | |
[10k] E C |
| B 2N2907 |
| | |
+-------+ [5.5]
| |
[1K] |
| |
C |
IO>--[2.7K]--B 2N2222 |
E |
| |
GND>-----------+---------------------+

--
JF

[Uncle Steve]

On Fri, May 10, 2013 at 07:42:40AM -0700, Jim Thompson wrote:
> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >Ok, this is a question that is not so battery-charger specific, but
> >is obviously related.
> >
> [snip]
> >but that is supposition that the 2n3055 somehow
> >limits the base current to some proportionate ratio to the collector-
> >emitter current available to it. Is that in any way a reasonable
> >explanation for what is occurring here?
>
> Nope, that is your main conceptual error.

Because the TIP147 is PNP and operates completely differently. Is the
issue here that the 3055 is 'fully on' with 5 uA driving the
2n2222?

Perhaps my frustration with arrangements other than the Sziklai Pair
is due to an irrational desire to decouple the 5v circuit from the 18V
section as much as possible. Other than in a darlington arrangement,
I am still having trouble making 2 2n2222 stages do what I want and
the frustration of things not working as I think they should is really
annoying.

But at pennies per transistor at least it's not expensive to fiddle.

[Jim Thompson]

On Fri, 10 May 2013 11:31:33 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Fri, May 10, 2013 at 07:42:40AM -0700, Jim Thompson wrote:
>> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> >Ok, this is a question that is not so battery-charger specific, but
>> >is obviously related.
>> >
>> [snip]
>> >but that is supposition that the 2n3055 somehow
>> >limits the base current to some proportionate ratio to the collector-
>> >emitter current available to it. Is that in any way a reasonable
>> >explanation for what is occurring here?
>>
>> Nope, that is your main conceptual error.
>
>Because the TIP147 is PNP and operates completely differently. Is the
>issue here that the 3055 is 'fully on' with 5 uA driving the
>2n2222?
>
>Perhaps my frustration with arrangements other than the Sziklai Pair
>is due to an irrational desire to decouple the 5v circuit from the 18V
>section as much as possible. Other than in a darlington arrangement,
>I am still having trouble making 2 2n2222 stages do what I want and
>the frustration of things not working as I think they should is really
>annoying.
>
>But at pennies per transistor at least it's not expensive to fiddle.
>
>
>Regards,
>
>Uncle Steve

Why don't you download LTspice? It's free. And use it as a learning
tool.

Then you'll be able to see the destructive currents.

[Uncle Steve]

So basically I'm approaching this problem backwards. I guess it's
time to step back and re-read some of the tutorial materials I didn't
understand the first time around.

[Jim Thompson]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

[snip]

Trying to zero in on the object of your endeavor... it sounds like you
want a trickle charger, BUT, when a 20W load is added, you want this
"regulator" to support that load, IF you have 18V available... is that
your target function?

[Uncle Steve]

On Fri, May 10, 2013 at 08:51:42AM -0700, Jim Thompson wrote:
> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> [snip]
>
> Trying to zero in on the object of your endeavor... it sounds like you
> want a trickle charger, BUT, when a 20W load is added, you want this
> "regulator" to support that load, IF you have 18V available... is that
> your target function?

Well, it has to trickle charge the battery if it is fully charged, but
otherwise must also support the load device if it is turned on, which
it will be most of the time.

Stated more generally, the charger has so much capacity, 3A in this
case, with the transformer I am currently using. So, the power
available to charge the battery is whatever isn't being used by the
load device. I realize I may not need PWM to control this thing after
all. The idea I would came before I understood exactly how lead-acid
batteries behave during the charge cycle. This is why I haven't
bothered using the microcontroller in-circuit yet.

[John Fields]

On Fri, 10 May 2013 11:31:33 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Fri, May 10, 2013 at 07:42:40AM -0700, Jim Thompson wrote:
>> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> >Ok, this is a question that is not so battery-charger specific, but
>> >is obviously related.
>> >
>> [snip]
>> >but that is supposition that the 2n3055 somehow
>> >limits the base current to some proportionate ratio to the collector-
>> >emitter current available to it. Is that in any way a reasonable
>> >explanation for what is occurring here?
>>
>> Nope, that is your main conceptual error.
>
>Because the TIP147 is PNP and operates completely differently. Is the
>issue here that the 3055 is 'fully on' with 5 uA driving the
>2n2222?
>
>Perhaps my frustration with arrangements other than the Sziklai Pair
>is due to an irrational desire to decouple the 5v circuit from the 18V
>section as much as possible. Other than in a darlington arrangement,
>I am still having trouble making 2 2n2222 stages do what I want and
>the frustration of things not working as I think they should is really
>annoying.
>
>But at pennies per transistor at least it's not expensive to fiddle.
>
>
>Regards,
>
>Uncle Steve

---
In the data sheets for your parts, notice that the values for Vce(sat)
and Vbe(sat) are given when Hfe = 10.

What that means is that if you need about (say) 100mA of collector
current for your load, then 10% of that (10mA) needs to be forced
through the b-e junction in order to force the transistor into
saturation.

Looking at a typical circuit using an NPN with a beta of (say) 100 to
300 at an Ic of about 100mA:


+5>-+--------+
| |
[Rb] [50R]
| |
O-> | |
| C
O--B NPN
E
|
GND>---------+

Assuming a Vce(sat) of 0.3V,

Vs - Vce(sat) 5V - 0.3V
Ic = --------------- = ----------- = 0.094 amperes
Rl 50R

Then, to force 10 percent of that through ther b-e junction we figure
out the value of Rb like this:


Vs - Vbe(sat) 5V - 0.8V
Rb = --------------- = --------------- = 446.8 ohms
0.1 * Ic 0.1 * 0.094A


420 ohms and 470 ohms are the closest 5% values and either would work
perfectly well since the natural beta of the transistor is much
greater than 10.

--
JF

[Jim Thompson]

On Fri, 10 May 2013 12:04:52 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Fri, May 10, 2013 at 08:51:42AM -0700, Jim Thompson wrote:
>> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> [snip]
>>
>> Trying to zero in on the object of your endeavor... it sounds like you
>> want a trickle charger, BUT, when a 20W load is added, you want this
>> "regulator" to support that load, IF you have 18V available... is that
>> your target function?
>
>Well, it has to trickle charge the battery if it is fully charged, but
>otherwise must also support the load device if it is turned on, which
>it will be most of the time.
>
>Stated more generally, the charger has so much capacity, 3A in this
>case, with the transformer I am currently using. So, the power
>available to charge the battery is whatever isn't being used by the
>load device. I realize I may not need PWM to control this thing after
>all. The idea I would came before I understood exactly how lead-acid
>batteries behave during the charge cycle. This is why I haven't
>bothered using the microcontroller in-circuit yet.
>
>
>Regards,
>
>Uncle Steve

Naaaah! Lose the micro. Micros are only applied to analog functions
by people who don't understand analog >:-}

What you need is a buck switcher charging you battery. Biggest
problem (for you) is tracking the battery temperature to avoid
overcharging.

I'm wondering if it might be possible to modify an off-the-shelf
alternator regulator to control a buck switcher... I'll pursue the
concept.

[Tim Wescott]

The biggest problem that I see in that drawing is that you've got the
collector of a PNP connected to a supply voltage that's higher than it's
emitter voltage. So the CB junction is forward biased and the BE
junction is reverse biased. So the 2N2906 is going to work in reverse --
the collector will work (poorly) as an emitter, and the emitter will work
(poorly) as a collector. The current gain will be around 1 or less.

The other biggest problem that I see is that you don't have nearly enough
current-limiting resistors in there.

If you turn the 2N2906 around then when the 2N2222 pulls current from its
base it'll deliver LOTS of current to the 2N3055 base. In fact, you'll
generally get too much current all around -- the 2N2222 will pull current
out of the 2N2906 that's limited only by the trickle of base current into
the 2N2222 and the 2N2222's beta, and the 2N2906 will put current into
the base of the 2N3055 that's limited only by it's base current and
beta. Everything will be hugely device- and temperature dependent, so
you'll constantly be fighting the thing not working or burning up.

You really want a resistor into the base of each transistor. Do that,
and you can significantly reduce the 1M resistance to the 2N2222, speed
up switching, and not burn out transistors.

--
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

[Uncle Steve]

I expect it's rather difficult to build an analog circuit to send
"powerok" at 38400bps to a serial port.

> What you need is a buck switcher charging you battery. Biggest
> problem (for you) is tracking the battery temperature to avoid
> overcharging.

PCM still isn't out of the question. The way battery voltage rises,
it might be feasible to use PCM if the input supply is variable, and
have the thing to a proper job independent of the voltage/current
capacity of the transformer. Who knows, perhaps next week a 36V-10A
switching power supply will fall from the sky and I'll want to use it
to charge the battery.

Mind you, I want to charge this battery fairly slowly to minimize
hydrogen-gas production as it will live indoors. Pulse charging
lead-acid may also be good to reduce sulfation of the plates, but I
don't know yet how much.

> I'm wondering if it might be possible to modify an off-the-shelf
> alternator regulator to control a buck switcher... I'll pursue the
> concept.

I wonder if I can make an inductor out of lacquered motor-winding wire.

[Uncle Steve]

In reality the PNP is connected the right way.

> The other biggest problem that I see is that you don't have nearly enough
> current-limiting resistors in there.

Well that's my thought too, but...

> If you turn the 2N2906 around then when the 2N2222 pulls current from its
> base it'll deliver LOTS of current to the 2N3055 base. In fact, you'll
> generally get too much current all around -- the 2N2222 will pull current
> out of the 2N2906 that's limited only by the trickle of base current into
> the 2N2222 and the 2N2222's beta, and the 2N2906 will put current into
> the base of the 2N3055 that's limited only by it's base current and
> beta. Everything will be hugely device- and temperature dependent, so
> you'll constantly be fighting the thing not working or burning up.

10k or 1M, the current into the base of the 3055 is never more than
38mA. Combined beta of the two small transistors is 180000, so Vb-e
of the 3055 sort-of ought to be 90mA. If I used a TIP122 it probably
would be, but then I'd really only need 3mA to turn it on. I suppose
this mean I could use a 2.2M resistor on the base of the 2n2222.

I have five 2n3055 parts so it would probably be better to actually
use them, not that they're all that expensive in the first place.

> You really want a resistor into the base of each transistor. Do that,
> and you can significantly reduce the 1M resistance to the 2N2222, speed
> up switching, and not burn out transistors.

I dunno. I'd be happier if I could just burn out transistors a little
more slowly so I could see it happening and stop it before they are
completely destroyed.

I have a 2n2906 that works in-circuit, but doesn't register at all on
my cheap transistor tester. The good ones show 120Hfe.

I guess it's just part of that "learn by destroying" thing.

[Tim Wescott]

Not if you have it the way it's pictured!

>
>> The other biggest problem that I see is that you don't have nearly
>> enough current-limiting resistors in there.
>
> Well that's my thought too, but...
>
>> If you turn the 2N2906 around then when the 2N2222 pulls current from
>> its base it'll deliver LOTS of current to the 2N3055 base. In fact,
>> you'll generally get too much current all around -- the 2N2222 will
>> pull current out of the 2N2906 that's limited only by the trickle of
>> base current into the 2N2222 and the 2N2222's beta, and the 2N2906 will
>> put current into the base of the 2N3055 that's limited only by it's
>> base current and beta. Everything will be hugely device- and
>> temperature dependent, so you'll constantly be fighting the thing not
>> working or burning up.
>
> 10k or 1M, the current into the base of the 3055 is never more than
> 38mA. Combined beta of the two small transistors is 180000, so Vb-e of
> the 3055 sort-of ought to be 90mA. If I used a TIP122 it probably would
> be, but then I'd really only need 3mA to turn it on. I suppose this
> mean I could use a 2.2M resistor on the base of the 2n2222.

The Vbe of the 3055 can't be 90mA, because Vbe denotes voltage.

Unless the 3055 is getting close to saturation you should be flowing
plenty of base current out of that 2906, and get way more than 38mA into
the base of the 3055.

So something's just not right.

Try connecting a 1K resistor to the base of the 2906 and manually
switching it to ground. You should get tons-o-current into the base of
the 3055 _assuming_ that there's enough voltage drop across the 2906 for
it to work.

If that doesn't lead to joy, back up and try connecting the base of the
3055 to +18V with a 2.2 to 10 ohm resistor -- that should turn the 3055
on good and hard. If it doesn't, don't mess around with anything else
until you get that figured out.

[Tim Wescott]

Ignore Jim's ranting. He's just a superannuated old geezer. Everyone
knows that analog circuits are only applied to analog functions by people
who don't understand microprocessors.

[Uncle Steve]

On Fri, May 10, 2013 at 12:50:41PM -0500, Tim Wescott wrote:
> On Fri, 10 May 2013 13:24:45 -0400, Uncle Steve wrote:
>
> > On Fri, May 10, 2013 at 11:40:38AM -0500, Tim Wescott wrote:
> >> On Fri, 10 May 2013 09:13:44 -0400, Uncle Steve wrote:
> >>
> >> > On Thu, May 09, 2013 at 10:57:58PM -0500, Tim Wescott wrote:
> >> >>
> >> >> OK. First, the drawing came through mangled. I hope I
> >> >> reconstituted it correctly.
> >> >
> >> > No, this is actually it:
> >> >
> >> >
> >> > 18V +----+--------__^------/\/\/--------+
> >> > | 2n3055| 0R5 |
> >> > | | 5W /
> >> > | | \ 5R10W
> >> > | | /
> >> > | | \

> >> > +-----v__| 2n2906 |

What picture?

> >> The other biggest problem that I see is that you don't have nearly
> >> enough current-limiting resistors in there.
> >
> > Well that's my thought too, but...
> >
> >> If you turn the 2N2906 around then when the 2N2222 pulls current from
> >> its base it'll deliver LOTS of current to the 2N3055 base. In fact,
> >> you'll generally get too much current all around -- the 2N2222 will
> >> pull current out of the 2N2906 that's limited only by the trickle of
> >> base current into the 2N2222 and the 2N2222's beta, and the 2N2906 will
> >> put current into the base of the 2N3055 that's limited only by it's
> >> base current and beta. Everything will be hugely device- and
> >> temperature dependent, so you'll constantly be fighting the thing not
> >> working or burning up.
> >
> > 10k or 1M, the current into the base of the 3055 is never more than
> > 38mA. Combined beta of the two small transistors is 180000, so Vb-e of
> > the 3055 sort-of ought to be 90mA. If I used a TIP122 it probably would
> > be, but then I'd really only need 3mA to turn it on. I suppose this
> > mean I could use a 2.2M resistor on the base of the 2n2222.
>
> The Vbe of the 3055 can't be 90mA, because Vbe denotes voltage.

Base-emitter current is what I meant.

> Unless the 3055 is getting close to saturation you should be flowing
> plenty of base current out of that 2906, and get way more than 38mA into
> the base of the 3055.

I'll measure it again. 37mA with one 2n3055 and 39mA with another.
I have a TIP122, and unlike the PNP TIP147, it shows .5mA when used as
a drop-in replacement for the 2n3055. So it seems that the base
current is being limited to what is required to saturate the power
transistor

> So something's just not right.
>
> Try connecting a 1K resistor to the base of the 2906 and manually
> switching it to ground. You should get tons-o-current into the base of
> the 3055 _assuming_ that there's enough voltage drop across the 2906 for
> it to work.

44mA.

> If that doesn't lead to joy, back up and try connecting the base of the
> 3055 to +18V with a 2.2 to 10 ohm resistor -- that should turn the 3055
> on good and hard. If it doesn't, don't mess around with anything else
> until you get that figured out.

10 ohms: 38mA

At this point the circuit is pretty minimal so it's difficult to say
whether there could be a component defect. Ignoring the LED/2.2k pair
on the output, that leaves a 10 ohm resister, the 2n3055, and a 5 ohm,
10 watt resistor for a load -- plus some wire.

[Tim Wescott]

_your_ picture. The emitter of the 2N2906 should be connected to +18V,
the collector should connect to the emitter of the 2N3055. You have the
emitter and the collector swapped.

Hah. OK, 10 ohms implies 380mV. That, plus the VBE of the 2N3055 is a
bit above 1V. You probably have something similar with the 2N2906, where
the VCB of the 2N3055 drops, dropping the VCE of the 2N2906, which makes
it go into saturation and reduces base current to the 2N3055 --
particularly if the 2N2906 is backwards.

[Tim Wescott]

On Fri, 10 May 2013 10:22:39 -0400, Uncle Steve wrote:

> On Fri, May 10, 2013 at 11:00:13PM +1000, Phil Allison wrote:
>>
>> "Uncle Steve"
>> >
>> > Nevertheless,
>> > there is nothing like making measurements to show what is in fact
>> > going on with these devices.
>>
>>
>> ** Give this man a Kewpie doll.
>
> I've always wanted a Kewpie doll.
>
> It's interesting that all of the literature and web-pages I've read so
> far have failed to impart an accurate sense of what these things do. I
> don't know whether that is because the learning curve is so steep, or
> whether the terminology is truly confusing to the uninitiated. I think
> it might be easier to understand electronics if circuit diagrams
> represented electron flow and electron charge potential more obviously.
> After all it's the electrons moving around that gets work done, correct?

Yes, it's electrons moving around that gets the work done. But in the
end it's usually easier to just think of current as a magic fluid that
goes in the direction indicated.

I'm not sure what you mean by "accurate sense of what these things do".
If you mean transistors, yes, the subject is both deep and wide. You can
do most anything with one of two models, though:

Model 1: there's a fixed drop from base to emitter of 0.65V, the
collector current equals beta * base current, and odd things happen in
saturation.

Model 2: There's a diode from base to emitter, and a diode from base to
collector. Both either point to or away from the base (that's the
meaning of the arrow on the emitter lead). There's a current source in
parallel with the collector. When current flows through the base-emitter
diode, the current source in parallel with the collector flows almost the
same amount of current (beta / (beta - 1), in fact, also known as alpha
in the old literature).

With that model you not only predict beta, but you can predict a lot of
behavior around saturation because that base-collector diode gets forward-
biased in saturation and starts to flow its own current.

[John Fields]

On Fri, 10 May 2013 15:07:05 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>I'll measure it again. 37mA with one 2n3055 and 39mA with another.
>I have a TIP122, and unlike the PNP TIP147, it shows .5mA when used as
>a drop-in replacement for the 2n3055. So it seems that the base
>current is being limited to what is required to saturate the power

>transistor.

---
Since the power transistor is wired as an emitter follower, you'll
never be able to run it into saturation, but it'll probably be good
enough for your application.

The best you'll be able to do is to get the emitter voltage equal to
the supply voltage minus the sum of Vbe of the power transistor and
Vce(sat) of the PNP.

If you like, try the circuit I posted for you; it just works. :-)

--
JF

[Jamie]

Uncle Steve wrote:
> On Thu, May 09, 2013 at 07:11:43PM -0700, Jim Thompson wrote:
>
>>On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
>>wrote:
>>
>>

>>>Ok, this is a question that is not so battery-charger specific, but
>>>is obviously related.
>>>

>>>So here's a circuit fragment:
>>>

>>>18V +----+--------__^------/\/\/--------+
>>> | 2n3055| 0R5 |
>>> | | 5W /
>>> | | \ 5R10W
>>> | | /
>>> | | \

>>> +------__v 2n2906 |

>>> | |
>>> | |
>>> 2n2222 +---| |
>>> | |>----+ |
>>> | | |
>>> / | |
>>> 1M \ | |
>>> / | |
>>> \ | |
>>> | | |
>>> | | |
>>> \ SW | |
>>> \ | |
>>> | | |
>>>5V +-----+ | |
>>> | |
>>>GND +---------------+------------------+
>>>

>>>So this circuit shows ~38mA going in to the base of the 2n3055, and
>>>~13.9V across the 5 ohm resistor. It gets warm quickly.
>>>
>>>If I change the 2n3055 for a TIP147 (PNP, beta 1k) and make the
>>>obvious changes to the 2n2906 to make it work, there is ~80mA current
>>>at the base of the TIP147, and ~14.1V across the 10W resistor.
>>>
>>>WTF, over?
>>>

>>>Needless to say I am happy that my $14.00 DVM has a transistor tester,
>>>because with 10k feeding the 2n2222 the 2n2906 doesn't last very long
>>>with a TIP147 in-circuit. Of course, in that configuration the base
>>>of a 2n3055 still shows 38mA. These results suggest that the
>>>base-emitter current of the 2n3055 cannot go any higher without a

>>>larger power supply, but that is supposition that the 2n3055 somehow

>>>limits the base current to some proportionate ratio to the collector-
>>>emitter current available to it. Is that in any way a reasonable
>>>explanation for what is occurring here?
>>
>>

>>Draw it up real purty, so you can tell PNP's from NPN's and can see
>>that current can only flow OUT of the NPN emitter and INTO a PNP
>>emitter... and DO THE MATH ;-)
>
>
>
> Sorry, I was tired and really mangled the schematic. Fixed above.
>
>
> Regards,
>
> Uncle Steve
>

The 2N2906 is orientated incorrectly. The emitter should be on the
18Volts and 2N3055 collector and of course the collector to the base
of the 2N3055.

As for the base drive to the 2N2906 from the 2N2222 collector, you
should be using a resistor, otherwise you'll let the blue smoke out.

Jamie

[Jim Thompson]

On Fri, 10 May 2013 12:53:49 -0500, Tim Wescott <t...@seemywebsite.com>

Sno-o-o-o-ort ;-)

[John Fields]

---
Wow, an echo claiming to be source?

--
JF

[Tim Wescott]

I thought you might like that.

[Jasen Betts]

hmm, your newsreader claims to be "nn" some sort of *nix prolly.

Assuming you're using X and something with an X86 processor
install "wine" and "xchm" then having downloaded the installer do

wine swcadiii.exe

after the installer ends do

wine 'C:\Program\ Files/LTC/SwCADIII/scad3.exe'

to launch it.

> I wouldn't characterize 3A as a trickle, but in essence I hope to end
> up with a battery charger that will charge the battery while it is
> under a moderate 20W+ load.

Many off-the-shelf regulated chargers will do that reasonably well.
Jim's the expert on lead-acid battery charging.

> I have bit-banged serial out on the
> microcontroller, so it will log status to the load device that way,
> and inform it when mains power fails.

that bit is probably going to need to be custom, or overpriced.

--
⚂⚃ 100% natural

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

[Jasen Betts]

On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:

> On Fri, May 10, 2013 at 11:13:48AM +0000, Jasen Betts wrote:
>> On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:
>> > Ok, this is a question that is not so battery-charger specific, but
>> > is obviously related.
>>

>> If you want to use a microcontroller you have to design
>> the low side switch part so that current flows out of
>> the 5V node, not into it.
>>
>> so dont do this:
>>
>> > | |
>> > | |
>> > \ SW |
>> > \ |
>> > | |
>> > 5V +-----------+ |
>> > |
>> > GND +-----------+-------------------------+
>
> When I actually hook this up to a microcontroller the 5V will be the
> output from the pin designated for PWM, assuming I stick with that
> strategy. As I said earlier, the switch is there to simulate a
> microcontroller.

but it doesn't even come close to simulating a microcontroller
output.


>> |
>> |
>> |/
>> 5V--+--[10K]--|
>> | |>|
>> | |
>> `----|<-----+
>> |
>> .---->|-----+
>> | |
>> | \ sw
>> | \
>> | |
>> +-----------+----------
>
> Not sure what the purpose of the second diode is there. Doesn't look
> like it can do much of anything.

it's part of the static protection circuitry typical of
microcontrollers in your circuit it does nothing. It's
there for completeness. if I left it out there would
be four of five people telling me. These diodes are
pretty wimpy, it's usualy best that they never conduct
any current.

[Jim Thompson]

On Fri, 10 May 2013 18:26:25 -0500, Tim Wescott <t...@seemywebsite.com>

Indeed! "Superannuated", that sure is a supercalifragilistic word for
old fart >:-}

You want a thrill for the day... look up your own actuarial data. I'm
12 years to EOL per the actuarial tables, 18 years if I follow my
Father's genetics, 3 years if I follow my Mother's (though that's
unlikely... she died in a botched heart valve procedure.. never decide
to have heart surgery done in Huntington, WV).

[Rheilly Phoull]

And perhaps a bit of a fiddle with some books or tutorials ??

[Jamie]

Wtf are you talking abt?

Jamie

[Uncle Steve]

It is not installed incorrectly.

What was biting me was perhaps the way I was driving the load on the
low-side of the 2n3055 transistor. I moved the load to the high-side
and changed the PNP transistor to source current from the 5V rail.
Now there's lots of current to drive the base of the 2n3055. But
there's only .2V developing across the thing.

2A, 17.4V from the p/s, 35W. The 2n3055 is only dissipating 400mA, so
no wonder it's running cool. Basically, I detect that the transformer
doesn't want to deliver more than 40W, so that's seems to be the limit
here. 55W my ass.

[Uncle Steve]

So if I use a 338 and set it to supply 14V, and then drive the pnp
from 18V the results might be better.

> If you like, try the circuit I posted for you; it just works. :-)

Maybe.

[Uncle Steve]

On Fri, May 10, 2013 at 05:47:58PM -0400, Jamie wrote:
> Uncle Steve wrote:
> >On Thu, May 09, 2013 at 07:11:43PM -0700, Jim Thompson wrote:
> >
> >>On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> >>wrote:
> >>
> >>
> >>>Ok, this is a question that is not so battery-charger specific, but
> >>>is obviously related.
> >>>
> >>>So here's a circuit fragment:
> >>>
> >>>18V +----+--------__^------/\/\/--------+
> >>> | 2n3055| 0R5 |
> >>> | | 5W /
> >>> | | \ 5R10W
> >>> | | /
> >>> | | \

> >>> +-----v__| 2n2906 |

No it isn't. What you're seeing is an optical illusion that only
makes you think it is oriented backwards.

> As for the base drive to the 2N2906 from the 2N2222 collector, you
> should be using a resistor, otherwise you'll let the blue smoke out.

I've got 400mA out of a 2n2907 at this time. No magic blue smoke yet.

[Uncle Steve]

On Fri, May 10, 2013 at 11:12:12PM +0000, Jasen Betts wrote:
> On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:
> > On Fri, May 10, 2013 at 11:13:48AM +0000, Jasen Betts wrote:
> >> On 2013-05-10, Uncle Steve <stev...@gmail.com> wrote:
> >> > Ok, this is a question that is not so battery-charger specific, but
> >> > is obviously related.
> >>
> >> If you want to use a microcontroller you have to design
> >> the low side switch part so that current flows out of
> >> the 5V node, not into it.
> >>
> >> so dont do this:
> >>
> >> > | |
> >> > | |
> >> > \ SW |
> >> > \ |
> >> > | |
> >> > 5V +-----------+ |
> >> > |
> >> > GND +-----------+-------------------------+
> >
> > When I actually hook this up to a microcontroller the 5V will be the
> > output from the pin designated for PWM, assuming I stick with that
> > strategy. As I said earlier, the switch is there to simulate a
> > microcontroller.
>
> but it doesn't even come close to simulating a microcontroller
> output.

A really sllloooooooowwwww microcontroller.

> >> |
> >> |
> >> |/
> >> 5V--+--[10K]--|
> >> | |>|
> >> | |
> >> `----|<-----+
> >> |
> >> .---->|-----+
> >> | |
> >> | \ sw
> >> | \
> >> | |
> >> +-----------+----------
> >
> > Not sure what the purpose of the second diode is there. Doesn't look
> > like it can do much of anything.
>
> it's part of the static protection circuitry typical of
> microcontrollers in your circuit it does nothing. It's
> there for completeness. if I left it out there would
> be four of five people telling me. These diodes are
> pretty wimpy, it's usualy best that they never conduct
> any current.

That makes a little more sense. Needless to say I want to get this
right before doing anything non-trival with the microcontroller.

[Uncle Steve]

I'm really completely uninterested in running anything Windows, even
if I could run it in a HVM domain. I have better things to do with
RAM.

> > I wouldn't characterize 3A as a trickle, but in essence I hope to end
> > up with a battery charger that will charge the battery while it is
> > under a moderate 20W+ load.
>
> Many off-the-shelf regulated chargers will do that reasonably well.
> Jim's the expert on lead-acid battery charging.

Constant voltage at 13.1V ought to be fine, but then powering a 12V
device from either 13.1 _or_ 12.8-12.2V is another matter. I have a
precision voltage reference and an op-amp to make a calibrated 12V
supply, but haven't got around to it yet.

> > I have bit-banged serial out on the
> > microcontroller, so it will log status to the load device that way,
> > and inform it when mains power fails.
>
> that bit is probably going to need to be custom, or overpriced.

The microcontroller running at 8MHz does 38400bps just fine with a
little state-machine I bashed out on Monday. It would do 115200, but
the interrupt vectors live in flash so I can't change them at
run-time, hence there's a 39 cycle register save/restore penalty I
can't seem to get rid of or reduce. If I did it in ASM it might be
doable, but C is so much easier. Damn you Atmel; damn you GCC!

[Jamie]

Play all the games you wish, and keep twisting the post around.

Jamie

[John Fields]

On Fri, 10 May 2013 20:01:24 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Fri, May 10, 2013 at 03:54:59PM -0500, John Fields wrote:
>> On Fri, 10 May 2013 15:07:05 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>>
>> >I'll measure it again. 37mA with one 2n3055 and 39mA with another.
>> >I have a TIP122, and unlike the PNP TIP147, it shows .5mA when used as
>> >a drop-in replacement for the 2n3055. So it seems that the base
>> >current is being limited to what is required to saturate the power
>> >transistor.
>>
>> ---
>> Since the power transistor is wired as an emitter follower, you'll
>> never be able to run it into saturation, but it'll probably be good
>> enough for your application.
>>
>> The best you'll be able to do is to get the emitter voltage equal to
>> the supply voltage minus the sum of Vbe of the power transistor and
>> Vce(sat) of the PNP.
>
>So if I use a 338 and set it to supply 14V, and then drive the pnp
>from 18V the results might be better.

---
Dunno.

Post a schematic.
---

>> If you like, try the circuit I posted for you; it just works. :-)
>
>Maybe.

---
Try it; what have you got to lose?

--
JF

[John Fields]

---
You have no idea, do you?

--
JF

[Uncle Steve]

Give me a break. All those little symbols look the same to me.

[Tim Wescott]

17.4V into 10 ohms is going to give you 1.74A. That's not the
transformer being "unwilling", that's you failing to load it down enough.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[ehsjr]

Why? He's got 5 ua max to the base of the 2N2222.

Ed

>
> Jamie
>

[P E Schoen]

I made some changes to your circuit to make it a current and voltage limited
source with a maximum current of 3 amps and a maximum voltage of about 6.6
volts. The OP's circuit as you interpreted it with LTspice is just a switch
with no regulation of current or voltage, and could be accomplished with a
simple switch or relay. I performed a parametric sweep of the load
resistance from 0.5 to 6.0 ohms. The circuit is far from optimum but it
performs the function of a linear battery charger.

For a screenshot of the simulation:
http://enginuitysystems.com/pix/UncleSteve1.png

Paul

============================================================

Version 4
SHEET 1 1592 708
WIRE -16 0 -192 0
WIRE 96 0 -16 0
WIRE 176 0 96 0
WIRE 320 0 272 0
WIRE 544 0 400 0
WIRE 624 0 544 0
WIRE 656 0 624 0
WIRE -16 64 -16 0
WIRE 224 96 224 64
WIRE 352 96 224 96
WIRE 464 96 416 96
WIRE 544 96 544 0
WIRE 544 96 528 96
WIRE 96 176 96 0
WIRE 224 176 192 176
WIRE 544 272 544 96
WIRE 544 272 448 272
WIRE 656 272 656 0
WIRE -16 288 -16 144
WIRE 144 288 144 240
WIRE 144 288 -16 288
WIRE 144 304 144 288
WIRE -192 352 -192 0
WIRE -80 352 -192 352
WIRE 352 352 64 352
WIRE 448 352 448 336
WIRE 144 400 144 384
WIRE 352 416 352 352
WIRE -80 448 -80 352
WIRE -32 448 -80 448
WIRE 64 448 64 352
WIRE 64 448 48 448
WIRE 80 448 64 448
WIRE 448 464 448 432
WIRE 448 464 416 464
WIRE -192 480 -192 352
WIRE -192 624 -192 560
WIRE 144 624 144 496
WIRE 144 624 -192 624
WIRE 352 624 352 512
WIRE 352 624 144 624
WIRE 656 624 656 352
WIRE 656 624 352 624
WIRE -192 688 -192 624
FLAG -192 688 0
FLAG 624 0 out
SYMBOL npn 176 64 R270
WINDOW 0 68 29 VRight 2
WINDOW 3 99 3 VRight 2
SYMATTR InstName Q1
SYMATTR Value 2N3055
SYMBOL npn 80 400 R0
SYMATTR InstName Q3
SYMATTR Value 2N2222
SYMBOL res 640 256 R0
WINDOW 3 36 68 Left 2
SYMATTR InstName R1
SYMATTR Value {RVAL}
SYMBOL voltage -192 464 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 18
SYMBOL res 64 432 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 2.7k
SYMBOL pnp 192 240 M270
WINDOW 0 61 61 VLeft 2
WINDOW 3 92 86 VLeft 2
SYMATTR InstName Q2
SYMATTR Value 2N2907
SYMBOL res 432 336 R0
SYMATTR InstName R2
SYMATTR Value 100
SYMBOL res 128 288 R0
SYMATTR InstName R4
SYMATTR Value 1k
SYMBOL res 416 -16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R5
SYMATTR Value 0.25
SYMBOL zener 464 336 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value BZX84C6V2L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL diode 352 80 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D2
SYMATTR Value MURS120
SYMBOL diode 464 80 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName D3
SYMATTR Value MURS120
SYMBOL res 208 80 R0
SYMATTR InstName R6
SYMATTR Value 47
SYMBOL npn 416 416 M0
SYMATTR InstName Q4
SYMATTR Value 2N2222
SYMBOL res 0 160 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R7
SYMATTR Value 2.7k
TEXT -176 656 Left 2 !;tran 1
TEXT 704 256 Left 2 !.step param RVAL 0.5 6.0 1\n.op

[John Fields]

On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
wrote:

>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.

---
"Nazi" would be a better choice, I think, since it seems to meet your
criteria.
---

>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.

---
Nonsense.

What you're proposing is that a noun, say something like 'glarf' would
tag someone who liked roses.

And 'glarfa' would tag someone who liked yellow roses...

and so on and so on...

Think about Reductio ad absurdum, and you might come to a more
pragmatic conclusion.
---

>These shortcomings of the English lexicon are representative of
>Orwellian linguistics at work in the real world.

---
Sounds like total and utter nonsense to me, but I'd like see what
you're talking about, especially the Orwellian influence.

Can you expound?

--
JF

[Uncle Steve]

On Sun, May 12, 2013 at 04:33:45PM -0500, John Fields wrote:
> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >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.
>
> ---
> "Nazi" would be a better choice, I think, since it seems to meet your
> criteria.

Nazi is like 'traitor', but the idea that National Socialism was a
false flag operation is amusing.

> >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.
>
> ---
> Nonsense.
>
> What you're proposing is that a noun, say something like 'glarf' would
> tag someone who liked roses.
>
> And 'glarfa' would tag someone who liked yellow roses...
>
> and so on and so on...
>
> Think about Reductio ad absurdum, and you might come to a more
> pragmatic conclusion.

The point I am attempting to make, perhaps badly, is that there are
certain ideas about behaviour which lack descriptive and unique
identifiers. This makes it more diffucult to think about such things,
indeed if the inclination to do so ever arises.

> ---
>
> >These shortcomings of the English lexicon are representative of
> >Orwellian linguistics at work in the real world.
>
> ---
> Sounds like total and utter nonsense to me, but I'd like see what
> you're talking about, especially the Orwellian influence.
>
> Can you expound?

Just did.


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

[ehsjr]

On 5/11/2013 11:24 PM, P E Schoen wrote:
> I made some changes to your circuit to make it a current and voltage
> limited source with a maximum current of 3 amps and a maximum voltage of
> about 6.6 volts. The OP's circuit as you interpreted it with LTspice is
> just a switch with no regulation of current or voltage, and could be
> accomplished with a simple switch or relay.

As I recall the op wanted to control the charger with the output
from a microprocessor, John's circuit allows. If I understand
the OP's position, he already has the voltage and current sensing
and control designed in his up.

Ed

> I performed a parametric
> sweep of the load resistance from 0.5 to 6.0 ohms. The circuit is far
> from optimum but it performs the function of a linear battery charger.

<snip>

[John Fields]

On Sun, 12 May 2013 21:09:06 -0400, Uncle Steve <stev...@gmail.com>

wrote:

>On Sun, May 12, 2013 at 04:33:45PM -0500, John Fields wrote:
>> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
>> wrote:
>>
>> >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.
>>
>> ---
>> "Nazi" would be a better choice, I think, since it seems to meet your
>> criteria.
>
>Nazi is like 'traitor', but the idea that National Socialism was a
>false flag operation is amusing.

---
Not to the survivors, I daresay.
---

>> >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.
>>
>> ---
>> Nonsense.
>>
>> What you're proposing is that a noun, say something like 'glarf' would
>> tag someone who liked roses.
>>
>> And 'glarfa' would tag someone who liked yellow roses...
>>
>> and so on and so on...
>>
>> Think about Reductio ad absurdum, and you might come to a more
>> pragmatic conclusion.
>
>The point I am attempting to make, perhaps badly, is that there are
>certain ideas about behaviour which lack descriptive and unique
>identifiers. This makes it more diffucult to think about such things,
>indeed if the inclination to do so ever arises.

---

I disagree, in that if certain behaviors can't be identified with a
single "catchword" they can always be described more gently with a few
well-chosen words and even perhaps a sentence.

---

>> >These shortcomings of the English lexicon are representative of
>> >Orwellian linguistics at work in the real world.
>>
>> ---
>> Sounds like total and utter nonsense to me, but I'd like see what
>> you're talking about, especially the Orwellian influence.
>>
>> Can you expound?
>
>Just did.

---
Silly me, I must have missed it.

What are you talking about?

--
JF

[Uncle Steve]

On Wed, May 15, 2013 at 05:31:14PM -0500, John Fields wrote:
> On Sun, 12 May 2013 21:09:06 -0400, Uncle Steve <stev...@gmail.com>
> wrote:
>
> >On Sun, May 12, 2013 at 04:33:45PM -0500, John Fields wrote:
> >> On Thu, 09 May 2013 20:59:01 -0400, Uncle Steve <stev...@gmail.com>
> >> wrote:
> >>
> >> >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.
> >>
> >> ---
> >> "Nazi" would be a better choice, I think, since it seems to meet your
> >> criteria.
> >
> >Nazi is like 'traitor', but the idea that National Socialism was a
> >false flag operation is amusing.
>
> ---
> Not to the survivors, I daresay.

It's dark amusement.

> >> >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.
> >>
> >> ---
> >> Nonsense.
> >>
> >> What you're proposing is that a noun, say something like 'glarf' would
> >> tag someone who liked roses.
> >>
> >> And 'glarfa' would tag someone who liked yellow roses...
> >>
> >> and so on and so on...
> >>
> >> Think about Reductio ad absurdum, and you might come to a more
> >> pragmatic conclusion.
> >
> >The point I am attempting to make, perhaps badly, is that there are
> >certain ideas about behaviour which lack descriptive and unique
> >identifiers. This makes it more diffucult to think about such things,
> >indeed if the inclination to do so ever arises.
>
> ---
> I disagree, in that if certain behaviors can't be identified with a
> single "catchword" they can always be described more gently with a few
> well-chosen words and even perhaps a sentence.

While that is technically correct, you should consider that it is the
fashion today to place everything in neat categories with easily
recognized labels: Democrat, Republican, Christian, White, Leftist,
etc. These identifiers mean nothing and everything simultaneously.
But if someone is identified as a Christian, what does that mean?
What kind of Christian? So we do have a few more categories in such
cases: Catholic, Protestant, Born Again Christian, Christian
Scientist, Coptic Christian. These identifiers differentiate sects,
but the taxonomy of Christianity stops there. We have no identifiers
to differentiate according to the variations in ontology that occur
within such groups, excepting administrative roles and such. Yet, the
ontological variance occurring within any arbitrary sect may be
considerably larger than the official ontological differences between
sects.

The language and Lexicon has been structured to conceal a large amount
of detail that pertains to the realpolitik of politics, religion, and
sociology. To wit: it is my impression that there is a rather large
hidden subculture of heroin within Western society, with its own
rituals, politics, and norms. I am not speaking of gutter addicts,
but of a functional group that spans the middle-class to the political
elite. In practice a secret society (or several secret societies),
who live and work among mere mortals largely undetected because they
seem to be adept at concealing their addiction and mores in so
far as they are different from those of the average Joe and Jane.
Even their use of language has numerous defining characteristics which
differentiate their speech from accepted use.

Consider if some non-trivial segment of Federal political office was
occupied by individuals who have an interest in securing and
perpetuating the conditions that give them access to the drug. Would
that not constitute something of an Orwellian threat?

> >> >These shortcomings of the English lexicon are representative of
> >> >Orwellian linguistics at work in the real world.
> >>
> >> ---
> >> Sounds like total and utter nonsense to me, but I'd like see what
> >> you're talking about, especially the Orwellian influence.
> >>
> >> Can you expound?
> >
> >Just did.
>
> ---
> Silly me, I must have missed it.
>
> What are you talking about?

Let's try that again, shall we?


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