Various Transistors Tested for Ic and Vce(sat)

[Jim Thompson]

Or an RK5744 or 5703.

Tim

I seem to remember some hearing aid toobz that had flexible leads.

...Jim Thompson

 

[Active8]

Make sure you have some resistance in the inductor. Depending on
simulator, you may need an initial-condition statement.

...Jim Thompson

or skip the bias point calculation?

 

[Jim Thompson]

news:[email protected]... [snip]
BTW, the *only* restraint on battery voltage is that is must be less
than the VF of the LED. The ED article is just plain BS!

...Jim Thompson

At least they're consistent...a BS explanation for a BS circuit! Purrrfect!
I can't even get the simulation to work :-(

Make sure you have some resistance in the inductor. Depending on
simulator, you may need an initial-condition statement.

...Jim Thompson

or skip the bias point calculation?

Depends on simulator and what unchecking that box actually does.

...Jim Thompson

 

[Watson A.Name - Watt Sun, Dark Remover]

[email protected] mentioned... [snip]

I was just trying to introduce the concept of "analysis" into circuits
of this sort.

Watson has hung his hat on VCE(sat) and that's only a small portion of
the variability he's observing.

I am certain that Watson, and most lurkers here, *cannot* analyze
(i.e. predict performance in advance of building) this circuit.

Fred Bloggs: Please hold your tongue so that I can incite some
thinking... if you simply spit out the answer all my attempts at
teaching people to think will be lost.

...Jim Thompson

I don't have a SPICE prog. Like Steve Ciarcia says, my favorite
programming language is solder.

Hey the thing's sitting there, working. For the inductor, I used a
Mouser #580-22R104.

(1) I didn't have in mind using Spice. Use pencil and paper.
Remember that stuff?

(2) What is the definition of "working"... as you *predicted* before
building it, or that it just happens to light the LED ?

Of course I use 'pencil and paper', or more like a calculator and
computer. I see this schematic posted here,
http://home.comcast.net/~rcmonsen/misc/ledtorch.jpg
I looked at R3 and said, well, there's a volt and a half minus a B-E
drop, or about .9V across the resistor. In order to get a hundred mA
thru Q2, say with a forced beta of 30, which is what the graphs for
2SD965 show, the base current has to be at least 3 mA. Well, with a
1k for R3, it's _not_ gonna happen! So I figure at the highest, it
should be 330 ohms. And I work from there.

Is that pencil and paper?

...Jim Thompson

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[Jim Thompson]

[email protected] mentioned... [snip]
I was just trying to introduce the concept of "analysis" into circuits
of this sort.

Watson has hung his hat on VCE(sat) and that's only a small portion of
the variability he's observing.

I am certain that Watson, and most lurkers here, *cannot* analyze
(i.e. predict performance in advance of building) this circuit.

Fred Bloggs: Please hold your tongue so that I can incite some
thinking... if you simply spit out the answer all my attempts at
teaching people to think will be lost.

...Jim Thompson

I don't have a SPICE prog. Like Steve Ciarcia says, my favorite
programming language is solder.

Hey the thing's sitting there, working. For the inductor, I used a
Mouser #580-22R104.

(1) I didn't have in mind using Spice. Use pencil and paper.
Remember that stuff?

(2) What is the definition of "working"... as you *predicted* before
building it, or that it just happens to light the LED ?

Of course I use 'pencil and paper', or more like a calculator and
computer. I see this schematic posted here,
http://home.comcast.net/~rcmonsen/misc/ledtorch.jpg
I looked at R3 and said, well, there's a volt and a half minus a B-E
drop, or about .9V across the resistor. In order to get a hundred mA
thru Q2, say with a forced beta of 30, which is what the graphs for
2SD965 show, the base current has to be at least 3 mA. Well, with a
1k for R3, it's _not_ gonna happen! So I figure at the highest, it
should be 330 ohms. And I work from there.

Is that pencil and paper?

...Jim Thompson

What does "forced beta" mean? Seriously! It's a rule-of-thumb... not
a reality! Revert to fundamentals, stop guessing, otherwise you'll
always be a hacker.

...Jim Thompson

 

[Robert C Monsen]

All phases of this oscillator ARE CALCULABLE. Please attempt to do so
instead of giving a hand-waving re-description of the nonsense in the
Electronic Design article. For instance, please write out...

Tsat = f(beta, Vcc, L, RL, rsat, etc.)

Likewise...

Toff = g(beta, Vcc, L, RL, rsat, etc.)

BTW, the *only* restraint on battery voltage is that is must be less
than the VF of the LED. The ED article is just plain BS!

Here is a guess, based on your hint about beta...

When charging, the rate of change of I with t is Vind/L. Vind is
1.5-Vce(sat), which unfortunately depends on I. Punt that.

When I > ß.Ib, then Vce will start to increase dramatically. That will cause
Q1 to turn on, and turn off Q2, starting the 'discharge' cycle.

The discharge cycle ends when the current runs out, and the LED can no
longer keep the voltage up; this causes Q1 to turn off, turning on Q1, and
restarting the charge cycle.

Thats what causes the oscillations.



The period is derived as follows

Ib*ß = (Vcc - V2ce)*t/L

so

Ib*ß*L/(Vcc-V2ce) = tc

Ib is (Vcc-V2be)/R2

therefore

charge time = tc = (Vcc-V2be)*ß*L/((Vcc-V2ce)*R2)

the max current, Imax, is tc * (Vcc - V2ce)/L

discharge time = td = Imax/(dI/dt), since only when I gets near 0 will the
LED drop the voltage enough to turn off Q1 and end the discharge cycle.

for discharge, di/dt is -(Vcc-Vf)/L. Thus,

td = tc * ((Vcc-V2ce)/L) / ((Vf-Vcc)/L)
= tc * (Vcc-V2ce)/(Vf-Vcc)

Regards
Bob Monsen

 

[Jim Thompson]

Here is a guess, based on your hint about beta...

When charging, the rate of change of I with t is Vind/L. Vind is
1.5-Vce(sat), which unfortunately depends on I. Punt that.

When I > ß.Ib, then Vce will start to increase dramatically. That will cause
Q1 to turn on, and turn off Q2, starting the 'discharge' cycle.

The discharge cycle ends when the current runs out, and the LED can no
longer keep the voltage up; this causes Q1 to turn off, turning on Q1, and
restarting the charge cycle.

Thats what causes the oscillations.



The period is derived as follows

Ib*ß = (Vcc - V2ce)*t/L

so

Ib*ß*L/(Vcc-V2ce) = tc

Ib is (Vcc-V2be)/R2

therefore

charge time = tc = (Vcc-V2be)*ß*L/((Vcc-V2ce)*R2)

the max current, Imax, is tc * (Vcc - V2ce)/L

discharge time = td = Imax/(dI/dt), since only when I gets near 0 will the
LED drop the voltage enough to turn off Q1 and end the discharge cycle.

for discharge, di/dt is -(Vcc-Vf)/L. Thus,

td = tc * ((Vcc-V2ce)/L) / ((Vf-Vcc)/L)
= tc * (Vcc-V2ce)/(Vf-Vcc)

Regards
Bob Monsen

Looks like a good shot at the math.

I'll take a look late tomorrow... gotta face a design review first ;-)

...Jim Thompson

 

[Active8]

[snip]
BTW, the *only* restraint on battery voltage is that is must be less
than the VF of the LED. The ED article is just plain BS!

...Jim Thompson

At least they're consistent...a BS explanation for a BS circuit! Purrrfect!
I can't even get the simulation to work :-(


Make sure you have some resistance in the inductor. Depending on
simulator, you may need an initial-condition statement.

...Jim Thompson

or skip the bias point calculation?

Depends on simulator and what unchecking that box actually does.

...Jim Thompson

With mine, it prevents the bias point from being calculated which
would put a steady current through L1, i.e., the step function
wouldn't be there to make it do it's di/dt thing or (1/L).Int(v dt)
That's *my* read on why a bias point calc would keep this circuit
from starting.

It got my vco's going I usually try that before setting an .IC

Oh. Thanks for the exercises

 

[Baphomet]

I seem to remember some hearing aid toobz that had flexible leads.

...Jim Thompson

http://amps.zugster.net/projects/sub-mini/

 

[Baphomet]

news:[email protected]... [snip]
BTW, the *only* restraint on battery voltage is that is must be less
than the VF of the LED. The ED article is just plain BS!

...Jim Thompson

At least they're consistent...a BS explanation for a BS circuit! Purrrfect!
I can't even get the simulation to work :-(

Make sure you have some resistance in the inductor. Depending on
simulator, you may need an initial-condition statement.

...Jim Thompson

or skip the bias point calculation?

AARGHHH! Finally got the damn thing to work in LT Spice. Jeez...I could have
set up 10 breadboards or used an abacus to figure out the circuit in less
time that it took me to simulate it. I'm sure that says much more about my
lack of ability with Spice than with the program itself ;-)

 

[Baphomet]

Looks like a good shot at the math.

I'll take a look late tomorrow... gotta face a design review first ;-)

...Jim Thompson

Just reworked the circuit a bit, turning it into your run of the mill cross
coupled multivibrator with added base to ground resistors (6.8k). Everything
seems to be more stable, more symmetrical, and less dependent upon
individual circuit parameters such as coil resistance (up to at least 50
ohms), transistor Hfe blah blah. LED current is also more reasonable and
transistor independent.

 

[Active8]

[snip]
BTW, the *only* restraint on battery voltage is that is must be less
than the VF of the LED. The ED article is just plain BS!

...Jim Thompson

At least they're consistent...a BS explanation for a BS circuit! Purrrfect!
I can't even get the simulation to work :-(


Make sure you have some resistance in the inductor. Depending on
simulator, you may need an initial-condition statement.

...Jim Thompson

or skip the bias point calculation?

AARGHHH! Finally got the damn thing to work in LT Spice. Jeez...I could have
set up 10 breadboards or used an abacus to figure out the circuit in less
time that it took me to simulate it. I'm sure that says much more about my
lack of ability with Spice than with the program itself ;-)

LOL! The abacus and the breadboard with 2000 hand drilled holes on
tenth inch centers! It's a good thing we have people like Mike and
Helmut around S.E.C. to help with LT Spice. Kevin's and others are
adept at Spice, too.

With PSpice you have guys that can help, but if it's Orcad's
interaction with PSpice (or anything Orcad), it becomes somewhat of
an arcane ritual involving incantations, pidgeon entrails, and
cloaks made of virgin hair But help is still there even if you
just need help getting the friggin' candles lit

I hear it coming... "I don't use Orcad ;-) ...Jim Thompson"

 

[Jim Thompson]

On Mon, 05 Jan 2004 15:52:06 GMT, Active8

[snip]

With PSpice you have guys that can help, but if it's Orcad's
interaction with PSpice (or anything Orcad), it becomes somewhat of
an arcane ritual involving incantations, pidgeon entrails, and
cloaks made of virgin hair But help is still there even if you
just need help getting the friggin' candles lit

I hear it coming... "I don't use Orcad ;-) ...Jim Thompson"

I don't use Orcad ;-)

If you are a PSpice user, choose Custom Install, and select PSpice
Schematics... *much* more intuitive than Capture.

...Jim Thompson

 

[Active8]

On Mon, 05 Jan 2004 15:52:06 GMT, Active8

[snip]

With PSpice you have guys that can help, but if it's Orcad's
interaction with PSpice (or anything Orcad), it becomes somewhat of
an arcane ritual involving incantations, pidgeon entrails, and
cloaks made of virgin hair But help is still there even if you
just need help getting the friggin' candles lit

I hear it coming... "I don't use Orcad ;-) ...Jim Thompson"

I don't use Orcad ;-)

If you are a PSpice user, choose Custom Install, and select PSpice
Schematics... *much* more intuitive than Capture.

...Jim Thompson

It installs with Orcad and I haven't tried it. Let's see...

There's no pdf docs but a glance at the help topics and menus has
revealed that it does pretty much the same stuff. PADs netlist,
BOM. No back annotation... not too big of a deal.

Uh, I'm getting tired of kicking myself in the ass, Jim. Care to
take over?

 

[Graham W]

I seem to remember some hearing aid toobz that had flexible leads.

XFY34 for example - but what is this 6.3V pentode EF76 ?
EF80 and 85 here in profusion!

 

[Ben Bradley]

In a post so important that it was crossposted to:
sci.electronics.components,
sci.electronics.misc,
alt.binaries.schematics.electronic,

On Sat, 3 Jan 2004 20:03:43 -0800, Watson A.Name - "Watt Sun, Dark

Make a little converter board the reroutes the pins for you so you
don't have to rewire the circuit every time you go from cbe to bce.
or add a separate socket

You could use three pin-driver chips as used in IC testors, and
with a little bit of programming you can just plug in any transistor
(the thing could even be programmed to recognize FET's, regulators and
UJT's) and it would figure out polarity, what pins are E, B, and C,
and give you characteristic curves. If you mechanically/themally
attach the transistor to a combination Peltier cell/small high-power
resistor, you can get curves involving varying temperature as well.

 

[John Woodgate]

I read in alt.binaries.schematics.electronic that Graham W
rce9.net>) about 'Various Transistors Tested for Ic and Vce(sat)', on
Mon, 5 Jan 2004:

XFY34 for example - but what is this 6.3V pentode EF76 ?

It's a wire-ended valve/tube. You identified the basic spec from the
type number. Look how much more helpful that 'EF76' is than 'XFY34' or
'6245', for example.

However, a GK32 is not an octal-based heptode with 5 V heater. (;-)

 

[Mark Zenier]

What does "forced beta" mean? Seriously! It's a rule-of-thumb... not
a reality! Revert to fundamentals, stop guessing, otherwise you'll
always be a hacker.

Why shouldn't John (a.k.a. Watson) just hack it. It's his hobby, not
his job. (And we're not in s.e.d, so tapping your MIT Honors ring isn't
going to mean squat).

Mark Zenier [email protected] Washington State resident

 

[Active8]

In a post so important that it was crossposted to:
sci.electronics.components,
sci.electronics.misc,
alt.binaries.schematics.electronic,


You could use three pin-driver chips

Like what? Is that 3 "pin driver" chips or "3-pin driver" chips? I
suspect the former.

as used in IC testors, and
with a little bit of programming you can just plug in any transistor
(the thing could even be programmed to recognize FET's, regulators and
UJT's) and it would figure out polarity, what pins are E, B, and C,
and give you characteristic curves. If you mechanically/themally
attach the transistor to a combination Peltier cell/small high-power
resistor, you can get curves involving varying temperature as well.

Yeah. While we're at it, we might as well make it a full blown
curve tracer like the IC tester. Why stop short? And since he's
testing these things in a boost-converter circuit, not a tranny
tester, it could be self-testing, giving all the relevant circuit
performance data.

We'll call it the TIRE Analyzer.

Tranny/IC/Reglator/EDN_Circuit[_analyzer] Analyzer. 'tis the age of
the acronym, after all.

 

[Mark Jones]

In news:[email protected] (Active8):

In a post so important that it was crossposted to:
sci.electronics.components,
sci.electronics.misc,
alt.binaries.schematics.electronic,


You could use three pin-driver chips

Like what? Is that 3 "pin driver" chips or "3-pin driver" chips? I
suspect the former.

as used in IC testors, and
with a little bit of programming you can just plug in any transistor
(the thing could even be programmed to recognize FET's, regulators and
UJT's) and it would figure out polarity, what pins are E, B, and C,
and give you characteristic curves. If you mechanically/themally
attach the transistor to a combination Peltier cell/small high-power
resistor, you can get curves involving varying temperature as well.

Yeah. While we're at it, we might as well make it a full blown
curve tracer like the IC tester. Why stop short? And since he's
testing these things in a boost-converter circuit, not a tranny
tester, it could be self-testing, giving all the relevant circuit
performance data.

We'll call it the TIRE Analyzer.

Tranny/IC/Reglator/EDN_Circuit[_analyzer] Analyzer. 'tis the age of
the acronym, after all.

I'd love to see the schematic/code for that beast!