What's a Good Sub for a 45V Zener?

[Winfield Hill]

Emoneg wrote...

Oh, shouldn't that be juxtaposition. }~~~

justaproposition

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Pooh Bear]

Mac wrote:

What about 3 x 15v 1 watt zeners in series?

Why 1 watt ? do you reckon you need to dissipate 3 watts to drive the base of a
transistor ?

Since ppl are being shitheads to me - thought I'd return the compliment !

Btw - 1 watt zeners typically have a lousy 'knee'. In fact most 'zeners' are
crap - period ! Use bandgap references instead !

Graham

 

[Pooh Bear]

"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:7jdr5054bntpufeta9nvpnkn1eqebi967i@4ax.com...
On Sun, 21 Mar 2004 09:43:13 -0500, the renowned "David"
dkuhajda@locl.net.spam> wrote:

Why not use one of the simple, cheap ics already made for the purpose
of
voltage conversion?

Or 3 of those 15v smoke alarm batteries.

Might be cheaper to snap together 5 9V batteries. ;-)
570mA @ 45V for a mere $7.

Yeah, I did; see my other followup.

There's no reason you can't use the E-B junctions and they should be
very consistent within a lot of transistors, but don't try to use the
transistors as transistors again afterward.

I usually clip off the collector lead and wrap it around the base lead.
Takes care of that problem. I just wonder if I can get a Base to
Collector junction to reliably zener or breakdown. One time I rectified
and filtered 120VAC to get about 170VDC, and I put that thru a 150k or
so resistor and across some transistors to see what voltage they would
break down at. Well, as soon as I connected the meter leads, the things
oscillated so nasty that every channel on the TV was nothing but hum
bars and buzzing in the audio. Wow, what a jammer.

You are a complete TWAT !

If you want a cheap 'zener' - actually an avalanche breakdown device - you
reverse bias the B-E junction !

Should typically give you 7 Volts.

Seems you guys fall into the very worst of the 'nerds' category - trying to
make bits you bought cheap work that were never intended to be used that way
- good luck to you !

I'll say good luck to planks of wood too.


Graham

 

[Pooh Bear]

Ban wrote:

Pooh Bear wrote:
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

TL431

Graham

Again a bad advice, this part works only up to 36V

Apologies - a single 431 is indeed linited to 36V.

So - use 2 in series. Get a really accurate reference voltage. Remember to use
1% resistors !

Actually - there's a neat trick to use a 'jacked-up' LM317 to supply an
accurate voltage source too - but I guess you're too anal to admit it.

and cannot dissipate the required power either.

Uh ? Pls describe your calcalation for power dissipation !

Graham

 

[Watson A.Name - \"Watt Su]

"Mac" <vk2evb@swiftdsl.com.au> wrote in message
news:405e8964$0$27651$61ce578d@news.syd.swiftdsl.com.au...

What about 3 x 15v 1 watt zeners in series?

I thought I said that below. In any case, here's the URL for the schem
of the circuit I was thinking of using, or a similar one with fewer
transistors. I also plan on making it 1 wattt or less depending on my
current needs.
http://ourworld.compuserve.com/homepages/bill_bowden/page4.htm#ps5.gif

I've been getting a grayed out paperclip on the attachments in this
lousy IE6 lately, maybe it's got to do with the security settings. In
any case, it won't let me d/l anything. Like that wackbards genome
post, I click on the paperclip and it's grayed out. Probably because
it's got a virus? Or it could possibly have a virus? Dunno..

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:105pt5jfaie5j29@corp.supernews.com...
I'm gonna make a 6V to 45V V boost circuit that can put out a few
mA, so
I don't need much power or current from the four AA cells. It will
be
used as a substitute for a 45V "B" battery, which are expensive and
hard
to find nowadays. I figure a simple flyback circuit with inductor
to
give the higher voltage. But I want to put a transistor between
base of
the output transistor and ground to cut out the power when the
rectified
and filtered DC gets up to 45VDC. I thought about using two
resistors
in a V divider, with the .6V B-E junction voltage as the reference
V.
But the .6V changes with temp, and this V converter will be used in
a
portable environment where it will be exposed to variations in temp.
So
that's not a good reference.

I thought that I could use five E-B junctions of cheap transistors
in
series, each of which break down at about 9V, totalling about 45VDC.
That way, the current waste will be minimal. I could also use a 45V
zener, but they're not too common, and I think I'd rather use two
24V
zeners or three 15 or 16V zeners, or whatever.

What do you think about using the C to B or C to E junctions of a
30V or
40V transistor? Or tying the E to B and using the B to C junction?
I
would have to select one for the right breakdown voltage, which
might
take a bit of doing. But I have a whole lotta transistors to pick
from.

Maybe I should just waste a lotta power and put a 45V zener right
across
the output. But that would waste a lotta battery power. Maybe I
should
use rechargeable AA cells.. Hmmm..


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
@@@@@@

 

[Watson A.Name - \"Watt Su]

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:405E9B54.E45BE0D8@hotmail.com...

"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

TL431

Yeah, i thought about that. But they're good only up to 36V.

Graham

 

[Emoneg]

| I've been getting a grayed out paperclip on the attachments in this
| lousy IE6 lately, maybe it's got to do with the security settings. In
| any case, it won't let me d/l anything. Like that wackbards genome
| post, I click on the paperclip and it's grayed out. Probably because
| it's got a virus? Or it could possibly have a virus? Dunno..
|
|
| > "Watson A.Name - "Watt Sun, the Dark Remover""

Tools/Options/Security uncheck the relevant bit.

Windows is probably flagging files with a .asc extension as dodgy.

I run AVG on this machine, it checks outgoing and incoming messages
including newsgroup postings. If you are worried then choose to save the
file and scan it.

DNA

 

[Aubrey McIntosh]

Jim Thompson <thegreatone@example.com> wrote in message news:<op1s50117k1chc2hr8n1h841bg3os3lfo2@4ax.com>...

Then why are you asking about 45V zener replacements?

All that is required is any available zener plus a transistor and two
resistors... voila, multiplied zener.

Connection is left as an exercise for the student... since there is a
finite number of ways to connect 4 components with only two terminals
net ;-)

...Jim Thompson
--

This is what I came up with.


My first reasoning was that the transistor dissipates the bulk of the
power, and the zener sets the control point, and at higher supply
voltage I wanted higher transistor current and had higher zener
current, so I put the zener current into the base. I never found a
multiplier solution with this approach.

My next approach was that a voltage divider would somehow scale the
zener voltage. This approach leads to

1. The classic Vbe multiplier.
2. The zener lifting the emitter voltage.

I initially rejected it because it wasn't "flat" but I don't envision
anything else.

The analysis gives:

V.div0 = V.zen + V.be
also
V.div1 = V.out * (R2 / (R1+R2))


Transistor magic makes V.div0 = V.div1. If that is too much hand
waving, there are some pages of current analysis and limits to
eliminate hfe.

V.out = (V.zen + V.be) * (R1 + R2) / R2
= (V.zen + V.be) * (1 + R1/R2)

Now that I put in the analytical part, I *still* want pretty pictures.
Using LTC spice, I would like to draw the curves with different zener
voltages. With the schematic listed below, I tried something like
..step dio 1N750(bv) 5 6 8 and get an error that doesn't help me.

What spice directive can I ad to get some pretty curves?



Version 4
SHEET 1 1832 680
WIRE -96 64 -96 -16
WIRE -96 -160 -96 -96
WIRE -96 -160 -64 -160
WIRE 576 -256 336 -256
WIRE 688 -256 576 -256
WIRE 576 16 576 96
WIRE 576 256 576 336
WIRE 512 -32 336 -32
WIRE 336 -32 336 -144
WIRE 336 -32 336 32
WIRE 336 112 336 256
WIRE 336 256 576 256
WIRE 576 -80 576 -256
WIRE 336 -224 336 -256
WIRE 336 -256 176 -256
WIRE 576 160 576 256
WIRE 256 -32 336 -32
FLAG -96 64 0
FLAG 688 -256 Out
IOPIN 688 -256 Out
FLAG -64 -160 Supply
IOPIN -64 -160 Out
FLAG 176 -256 Supply
IOPIN 176 -256 In
FLAG 576 336 0
FLAG 256 -32 Div
IOPIN 256 -32 Out
SYMBOL res 352 -128 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R1
SYMATTR Value 47K
SYMBOL npn 512 -80 R0
SYMATTR InstName Q1
SYMATTR Value 2N5550
SYMBOL current -96 -16 R180
WINDOW 0 24 88 Left 0
WINDOW 3 24 0 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I1
SYMATTR Value 1
SYMBOL res 320 16 R0
SYMATTR InstName R2
SYMATTR Value 4K7
SYMBOL zener 592 160 R180
WINDOW 0 24 72 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName D1
SYMATTR Value 1N750
SYMATTR Description Diode
SYMATTR Type diode
TEXT -114 138 Left 0 !.op
TEXT -112 184 Left 0 !.step oct I1 1m 20m 8

 

[Jim Thompson]

On 23 Mar 2004 09:28:02 -0800, mcintosh@spam.vima.austin.tx.us (Aubrey
McIntosh) wrote:

Jim Thompson <thegreatone@example.com> wrote in message news:<op1s50117k1chc2hr8n1h841bg3os3lfo2@4ax.com>...

Then why are you asking about 45V zener replacements?

All that is required is any available zener plus a transistor and two
resistors... voila, multiplied zener.

Connection is left as an exercise for the student... since there is a
finite number of ways to connect 4 components with only two terminals
net ;-)

...Jim Thompson
--


This is what I came up with.


My first reasoning was that the transistor dissipates the bulk of the
power, and the zener sets the control point, and at higher supply
voltage I wanted higher transistor current and had higher zener
current, so I put the zener current into the base. I never found a
multiplier solution with this approach.

My next approach was that a voltage divider would somehow scale the
zener voltage. This approach leads to

1. The classic Vbe multiplier.
2. The zener lifting the emitter voltage.

I initially rejected it because it wasn't "flat" but I don't envision
anything else.

The analysis gives:

V.div0 = V.zen + V.be
also
V.div1 = V.out * (R2 / (R1+R2))


Transistor magic makes V.div0 = V.div1. If that is too much hand
waving, there are some pages of current analysis and limits to
eliminate hfe.

V.out = (V.zen + V.be) * (R1 + R2) / R2
= (V.zen + V.be) * (1 + R1/R2)

Now that I put in the analytical part, I *still* want pretty pictures.
Using LTC spice, I would like to draw the curves with different zener
voltages. With the schematic listed below, I tried something like
.step dio 1N750(bv) 5 6 8 and get an error that doesn't help me.

Your analysis is correct.

IIRC something like a 6.8V zener in combination with the transistor
will be pretty close to flat.

I don't know the verbiage for LTSpice. But you need to step a model
parameter, for example, in PSpice:

..STEP NPN Q2N2222 (IS) LIST 1e-16 2e-16 3e-16 4e-16 5e-16

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Throughout the history of this great country there have actually
been people of only two political persuasions: fighters and yellow-
bellies. WE MUST NOT LET THE LATTER PREVAIL IN THE NEXT ELECTION!

 

[Rolavine]

How about 2 LM317's? They have a high voltage one too but I think it is only
about 40 volts. Since Zeners suck you could just feed their adjustment pins off
a 3 resistor voltage divider on the output.

Rocky

 

[Mark Zenier]

"Watson A.Name - \"Watt Sun, the Dark Remover\"" <NOSPAM@dslextreme.com> wrote in message news:<1060gafnavf2va1@corp.supernews.com>...

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:405E9B54.E45BE0D8@hotmail.com...


"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

TL431

Yeah, i thought about that. But they're good only up to 36V.

But what's the end of life voltage of a 45 volt battery? I'd expect
a circuit that uses them to work down to 30 volts or so.

Mark Zenier mzenier@eskimo.com

 

[Aubrey McIntosh]

Jim Thompson <thegreatone@example.com> wrote in message news:<85t060hsf0qf8qo4p7v4bhjk5esl3b9cvl@4ax.com>...

On 23 Mar 2004 09:28:02 -0800, mcintosh@spam.vima.austin.tx.us (Aubrey
McIntosh) wrote:




IIRC something like a 6.8V zener in combination with the transistor
will be pretty close to flat.

I added a resistor and a pnp transistor. Two of the current voltage
points on the simulated curve are (10mA, 43.24V) and (500mA, 48.84V).
If I understand correctly, the impedence looking into it is del.V /
del.A = 11.4 ohm.

It seemed important to keep the current in the multiplied zener near
10mA.

 

[Aubrey McIntosh]

Jim Thompson <thegreatone@example.com> wrote in message news:<85t060hsf0qf8qo4p7v4bhjk5esl3b9cvl@4ax.com>...

On 23 Mar 2004 09:28:02 -0800, mcintosh@spam.vima.austin.tx.us (Aubrey
McIntosh) wrote:


IIRC something like a 6.8V zener in combination with the transistor
will be pretty close to flat.

I have added a resistor and a transistor, and the output voltage curve
is much flatter. Two of the points on the simulation output are
(10mA, 43.21V ) (500mA, 48.87V )

If I understand, that is an impedence looking into it of
del.V / del.A = 12.5 ohm

 

[Rich Grise]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:105pt5jfaie5j29@corp.supernews.com...

I'm gonna make a 6V to 45V V boost circuit that can put out a few mA, so
I don't need much power or current from the four AA cells. It will be
used as a substitute for a 45V "B" battery, which are expensive and hard
to find nowadays. I figure a simple flyback circuit with inductor to
give the higher voltage. But I want to put a transistor between base of
the output transistor and ground to cut out the power when the rectified
and filtered DC gets up to 45VDC. I thought about using two resistors
in a V divider, with the .6V B-E junction voltage as the reference V.
But the .6V changes with temp, and this V converter will be used in a
portable environment where it will be exposed to variations in temp. So
that's not a good reference.

What about just a 44.4v ;-) zener from the 45V. to the base of a crowbar
transistor? Or just to the negative feedback element of your regulator?

Have Fun!
Rich

 

[Rich Grise]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message >

I've been getting a grayed out paperclip on the attachments in this
lousy IE6 lately, maybe it's got to do with the security settings. In
any case, it won't let me d/l anything. Like that wackbards genome
post, I click on the paperclip and it's grayed out. Probably because
it's got a virus? Or it could possibly have a virus? Dunno..

You're being nannied by mommie MICRO$~1. I dunno about IE6, but in
butthook distress 6, I can click tools->options->security tab->
uncheck "Do not allow attachments..."

Good Luck!
Rich

 

[Watson A.Name \"Watt Sun]

Jim Thompson wrote:

On Sun, 21 Mar 2004 13:20:54 -0800, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

[snip]

Seriously, I believe you that it works, a schematic of it will do fine,
since I can build one from it. But I don't have any spice, I'm a
soldering fool with a hot soldering iron, ready to do some damage to a
PC board. That's all, no simulations needed. Really.

Version 4
SHEET 1 2132 1112

[snip]

Then why are you asking about 45V zener replacements?

All that is required is any available zener plus a transistor and two
resistors... voila, multiplied zener.

Connection is left as an exercise for the student... since there is a
finite number of ways to connect 4 components with only two terminals
net ;-)

...Jim Thompson

Here's my version of a constant voltage source, using a transistor and
zener:
(View with courier font)


Watson's Constant Current Source AKA Voltage Reference Mar 24,'04


6.2k (trim to
exactly 1 mA)
o---+---------/\/\/\-----\ /-----------------+
| E\ / --> |
+V | ------ I == 1 mA |
| PNP | |
| | |
| / | |
+--------|<-------------+------/\/\/\--+ |
/ 2.2k | +------Vout
6.8V Zener --- | (I =0)
GND |
\
/
\ R= 1k per volt
/
|
---
GND

 

[Watson A.Name \"Watt Sun]

Emoneg wrote:

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote in message news:105sh7rnir6abf9@corp.supernews.com...

| "Emoneg" <Emoneg@nothere.com> wrote in message
| news:qPo7c.27$%l2.10@newsfe1-win...

| > LTspice, available for free from

| > http://www.linear.com/software/

| > A full featured free unrestricted spice simulator.

| > Also useful for communicating circuit diagrams and ideas.

| > UCC380X datasheet available 'free' from

| > http://www.ti.com

| > Understand what you build

| Thank you, but understanding what one builds does not require a spice
| program, especially when you have the Real Thing.

| It also locks you into their products. TANSTAAFL.

| > DNA

If you looked at the circuit provided, using LTspice, you would see that
it does not contain any proprietry LT parts. It is a simple
implementation of the guts of a UCC380X (UC384X).

You are not, in any way locked into using their products.

If other manufacturers produce Spice models you can add them in. Like I
say it's full featured, free and unrestricted. It also gives me an
opportunity to express my ideas to you in a format available to both of
us. I could use it to give you a circuit diagram.

The first time I used Spice in anger, not this version a restricted free
copy of something else, was on a unit that was and had been in
production for some years that was failing final test.

The person who designed it 'had the real thing'. It turned out it was
borderline unstable. I could have spent ages drawing bode plots and such
stuff.

These days I might be able to. In fact most times I can crank some sums
on a calculator with a bit of paper, only because spice has given me the
experience, but I wouldn't.

I modelled it in spice and demonstrated that it was borderline unstable
with a 'bandwidth of 4KHz.

I used the knowledge I had at the time made it stable in spice and
increased the bandwidth to 24KHz....... yes the original engineer was
that far off what was possible an he was working with the real thing.

I implemented the mods and the thing went ape shit at 10KHz. I'd misread
a resistor value. I changed it and it worked. I put the wrong resistor
value in spice and spice went unstable at....... 10KHz.

It takes a minimum of three separate snubbers to deal with a forward
converter. I could have read someone elses attempt to explain what's
going on in words and got nowhere. I could have cried tears over the
real thing. I stuffed it up spice and isolated what was playing with
what went back to the real thing and sorted it.

In the process I discovered where the voltage spike on the rectifier
comes from and tamed that as well. I could used spice to explain it to
you and you'd understand.

I think I might do that today.

Spice is a mother beautiful tool. Next time I meet some 'hard man'
luddite who denies this for whatever reason I'll consign him to the
ignorant bucket.

Chances are that, once again, I'll be fixing his broken thing.

DNA

I d/l'd it (4 megs in 2.5 seconds) on my PC at work and installed it
just so I could print out your schematic. It works but I don't know how
to use it.

But I see on the schem that there is a circle with VREF 2.5V by it.
Well, that doesn'ttell me anything about how to do it in the real world.
One presumes that it really should be a TL431 with a resistor to V+,
but there's nothing there that tells one that.

What _IS_ this MSWITCH symbol?? A power FET? Surely you don't expect
me to sit there flipping a switch a hundred thousand times a second!?!?!
DOH! Why are D1 and D2 in series?? Etc., etc., etc...

 

[Jim Thompson]

See "HighVoltageOperationOfTL431.pdf" on the S.E.D/Schematics Page of
my website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Throughout the history of this great country there have actually
been people of only two political persuasions: fighters and cowards.
WE MUST NOT LET THE LATTER PREVAIL IN THE NEXT ELECTION!

 

[Watson A.Name \"Watt Sun]

Pooh Bear wrote:

Mac wrote:

What about 3 x 15v 1 watt zeners in series?

Why 1 watt ? do you reckon you need to dissipate 3 watts to drive the base of a
transistor ?

Since ppl are being shitheads to me - thought I'd return the compliment !

Btw - 1 watt zeners typically have a lousy 'knee'. In fact most 'zeners' are
crap - period ! Use bandgap references instead !

Yeah, but.. Where do I find a 45V bandgap ref? ;-)

Maybe I should find a 45V neon lamp??

> Graham

 

[Jim Thompson]

On Wed, 24 Mar 2004 13:15:19 -0800, "Watson A.Name \"Watt Sun - the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

[snip]

Yeah, but.. Where do I find a 45V bandgap ref? ;-)

[snip]

See "HighVoltageOperationOfTL431.pdf" on the S.E.D/Schematics Page of
my website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Throughout the history of this great country there have actually
been people of only two political persuasions: fighters and cowards.
WE MUST NOT LET THE LATTER PREVAIL IN THE NEXT ELECTION!