Transistors

[Tim Wescott]

On Fri, 10 May 2013 16:03:33 -0700, Jim Thompson wrote:

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

On Fri, 10 May 2013 13:01:57 -0400, Uncle Steve wrote:

On Fri, May 10, 2013 at 09:17:08AM -0700, Jim Thompson wrote:
On Fri, 10 May 2013 12:04:52 -0400, Uncle Steve <stevet810@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
stevet810@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 >:-}

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

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.

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

I thought you might like that.


--
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

 

[Jim Thompson]

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

On Fri, 10 May 2013 16:03:33 -0700, Jim Thompson wrote:

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

On Fri, 10 May 2013 13:01:57 -0400, Uncle Steve wrote:

On Fri, May 10, 2013 at 09:17:08AM -0700, Jim Thompson wrote:
On Fri, 10 May 2013 12:04:52 -0400, Uncle Steve <stevet810@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
stevet810@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 >:-}

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

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.

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

I thought you might like that.

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).


...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)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 Fri, May 10, 2013 at 03:39:18PM -0500, Tim Wescott wrote:

On Fri, 10 May 2013 15:07:05 -0400, Uncle Steve wrote:

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 |
| |
| |
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.

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.

In reality the PNP is connected the right way.

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

What picture?

_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.

It is not installed incorrectly.

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.

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.

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.


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.

 

[Rheilly Phoull]

On 10/05/13 23:46, Jim Thompson wrote:

On Fri, 10 May 2013 11:31:33 -0400, Uncle Steve <stevet810@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 <stevet810@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.

...Jim Thompson

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

 

[Uncle Steve]

On Fri, May 10, 2013 at 03:54:59PM -0500, John Fields wrote:

On Fri, 10 May 2013 15:07:05 -0400, Uncle Steve <stevet810@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.

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

Maybe.


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.

 

[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 <stevet810@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.

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.


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.

 

[Uncle Steve]

On Fri, May 10, 2013 at 11:12:12PM +0000, Jasen Betts wrote:

On 2013-05-10, Uncle Steve <stevet810@gmail.com> wrote:
On Fri, May 10, 2013 at 11:13:48AM +0000, Jasen Betts wrote:
On 2013-05-10, Uncle Steve <stevet810@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.


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.

 

[Jamie]

John Fields wrote:

On Fri, 10 May 2013 17:47:58 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> 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 <stevet810@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


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

Wtf are you talking abt?

Jamie

 

[Uncle Steve]

On Fri, May 10, 2013 at 11:04:09PM +0000, Jasen Betts wrote:

On 2013-05-10, Uncle Steve <stevet810@gmail.com> wrote:
On Fri, May 10, 2013 at 07:38:44AM -0700, Jim Thompson wrote:
On Fri, 10 May 2013 08:58:49 -0400, Uncle Steve <stevet810@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 <stevet810@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.

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'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!


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.

 

[John Fields]

On Fri, 10 May 2013 20:01:24 -0400, Uncle Steve <stevet810@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 <stevet810@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

 

[Jamie]

Uncle Steve wrote:

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 <stevet810@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.


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.


Regards,

Uncle Steve

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

Jamie

 

[Uncle Steve]

On Fri, May 10, 2013 at 08:46:00PM -0400, Jamie wrote:

Uncle Steve wrote:

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 <stevet810@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.


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.


Regards,

Uncle Steve

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

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


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.

 

[John Fields]

On Fri, 10 May 2013 20:14:11 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

John Fields wrote:

On Fri, 10 May 2013 17:47:58 -0400, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> 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 <stevet810@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


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

Wtf are you talking abt?
---

You have no idea, do you?

--
JF

 

[Tim Wescott]

On Fri, 10 May 2013 19:56:29 -0400, Uncle Steve wrote:

On Fri, May 10, 2013 at 03:39:18PM -0500, Tim Wescott wrote:
On Fri, 10 May 2013 15:07:05 -0400, Uncle Steve wrote:

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 |
| |
| |
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.

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.

In reality the PNP is connected the right way.

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

What picture?

_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.

It is not installed incorrectly.

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.

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.

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.

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]

On 5/10/2013 5:47 PM, 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 <stevet810@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.

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 <stevet810@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 <stevet810@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
representative of Orwellian linguistics at work in the real world.

 

[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 <stevet810@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 <stevet810@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