Using 1N4001 as Zener Diode

  • Thread starter Watson A.Name - "Watt Sun
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Watson A.Name - "Watt Sun

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This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf



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I don't see any 1n4001's being used as Zener diodes at all.
I see two standard 1n4001 diodes being used to provide an additional voltage
drop of .6-.7v each diode.

Why not use a single 1n4002? Because it would have the same forward biased
voltage drop as a single 1n4001.

David

Watson A.Name - Watt Sun, Dark Remover <alondra101@hotmail.com> wrote in
message news:MPG.1a217660a2ce553998993c@news.dslextreme.com...
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf



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###Got a Question about ELECTRONICS? Check HERE First:###
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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
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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@@
Click to expand...
 
On Sun, 16 Nov 2003 11:57:53 -0800, Watson A.Name - "Watt Sun, Dark
Remover" <alondra101@hotmail.com> wrote:

This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf
Click to expand...

That is a really weird circuit. It looks to me that all three diodes
in the string are drawn backwards... it doesn't seem to do anything
sensible as shown.

John
 
Thats a typical circuit to extract a stable clock from a bridge rect.

Cheers

"Watson A.Name - Watt Sun, Dark Remover" <alondra101@hotmail.com> wrote in message
news:MPG.1a217660a2ce553998993c@news.dslextreme.com...
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf



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###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@@
Click to expand...
 
John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:
http://www.repairfaq.org/sam/hwpl1sch.pdf


That is a really weird circuit. It looks to me that all three diodes
in the string are drawn backwards... it doesn't seem to do anything
sensible as shown.

John
Click to expand...
That's how it looks to me, too. :-|

Bob
 
"John Larkin" <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> schreef in
bericht news:9fnfrv86b36epm14ethn5hgeqeq5q837im@4ax.com...
On Sun, 16 Nov 2003 11:57:53 -0800, Watson A.Name - "Watt Sun, Dark
Remover" <alondra101@hotmail.com> wrote:

This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf


That is a really weird circuit. It looks to me that all three diodes
in the string are drawn backwards... it doesn't seem to do anything
sensible as shown.
Click to expand...
If C1A is charged, and C1B is discharged (after a flash), and the
bridge is zerocrossing the AC input, well I don't know ;)

Weird indeed, but not sure if the diodes are reversed.

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
On Sun, 16 Nov 2003 11:57:53 -0800, Watson A.Name - "Watt Sun, Dark
Remover" <alondra101@hotmail.com> wrote:

This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf
Click to expand...

Looks like a reverse blocking 11.4V Zener to me.
 
Bob Parker <bobp@bluebottle.com> writes:

John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

http://www.repairfaq.org/sam/hwpl1sch.pdf


That is a really weird circuit. It looks to me that all three diodes
in the string are drawn backwards... it doesn't seem to do anything
sensible as shown.

John

That's how it looks to me, too. :-|
Click to expand...
I agree it is weird and I need to look into it more closely. I have
tried to contact the owner to see if they can more carefully trace the
relevant portion of the circuit.

Realize though that the output of the bridge is 120 Hz pulses and what's
relevant is what happens during the rise of each pulse to determine if
the SCR gets triggered (to charge the cap) or doesn't (to light the
ready light). I think that if Q1 were NPN and the pot were a higher
value, it would make more sense with the diodes in their current
direction.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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In article <3fb80f86@news.greennet.net>, dkuhajda@locl.net.spam
mentioned...
I don't see any 1n4001's being used as Zener diodes at all.
I see two standard 1n4001 diodes being used to provide an additional voltage
drop of .6-.7v each diode.
Click to expand...
Looked to me like the base of the transistor was 300V or more, and the
bottom of the CR7 1N4001 would have a lot lower voltage on it. But
then now that I've looked at it more, I see your point. I'm now
wondering what the whole purpose of the transistor is.

Anyway, it looked to me like when the unit was first turned on, the
two 1N4001s would have over 300V across them, until C1A charged up.
And whenever the flash using C1A was triggered, the cap would
discharge and the diodes would again have over 300V across them. I
guess I'll have to do some more studying of the circuit to get
uncornfused.


Why not use a single 1n4002? Because it would have the same forward biased
voltage drop as a single 1n4001.

David

Watson A.Name - Watt Sun, Dark Remover <alondra101@hotmail.com> wrote in
message news:MPG.1a217660a2ce553998993c@news.dslextreme.com...
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf
Click to expand...

--
@@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 Sun, Dark Remover" <alondra101@hotmail.com> wrote:

This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf
Click to expand...
I don't think Samuel M. Goldwasser did a very good job redrawing it.

If you reverse the thyristor, reverse CR5, 6 and 7. Swap the location of Q1
and R1 then it makes sense.

That way Q1 and so the thyristor are on until the voltage across R3 exceeds
the 12v across the zener and diode combination (roughly).

Not sure why there are two diodes. I know the temperature coefficient of a
silicon diode is an inverse match for a zener of about 6v. Are two diodes a
worthwhile match for a 10v zener?
 
Sam Goldwasser <sam@saul.cis.upenn.edu> wrote:

I agree it is weird and I need to look into it more closely. I have
tried to contact the owner to see if they can more carefully trace the
relevant portion of the circuit.
Click to expand...
Sorry about the incorrect attribution of blame in my other post, I had a
feeling the circuit must have come from a traced PCB.
 
"Watson A.Name - Watt Sun, Dark Remover" <alondra101@hotmail.com> wrote in
message news:MPG.1a217660a2ce553998993c@news.dslextreme.com...
| This is an interesting schematic. I hadn't noticed this one before on
| Sam's website. Apparently the two 1N4001s are connected in series to
| be used as two zener diodes. Why not use a single 1N4002? Maybe to
| hand select for the right combination of the two to give the total
| breakdown voltage. I'm guessing about 150V each. Never tried it,
| tho.
|
| http://www.repairfaq.org/sam/hwpl1sch.pdf
|
|
|

A standard diode in series with a zener diode as in CR5 and CR6 is a
standard way to temperature compensate a zener. Zeners also have to be
protected from carrying any forward current (shifts the zener voltage). CR7
probably compensates for the Vbe of Q1.
Some designers tend to get totally anal retentive about temperature
compensation.

In a circuit like this, the SCR is used to charge the storage caps from the
DC source. It is supposed to allow for a fast charge with a trickle supplied
by IL1 lamp. The SCR has to turn off before the strobe is triggered or the
lamp will stay continuously on (and be destroyed).

In Royer type dc-dc converters used in many older flashes, the converter is
current limiting and shuts down when the lamp flashes.

I agree though that something in the direction of the D5,6,7 string seems to
be amiss

Oppie.

--
For valid response address, remove the '1' following oppie
_________________
 
nospam <nospam@nospam.invalid> writes:

Sam Goldwasser <sam@saul.cis.upenn.edu> wrote:

I agree it is weird and I need to look into it more closely. I have
tried to contact the owner to see if they can more carefully trace the
relevant portion of the circuit.

Sorry about the incorrect attribution of blame in my other post, I had a
feeling the circuit must have come from a traced PCB.
Click to expand...
http://www.repairfaq.org/sam/hwpl1sch.pdf

No, the attribution is more or less correct. I'm the one who traced it
and was bothered by the regulator from the beginning.

It would almost make sense if Q1 were an NPN but that part number is
definitely PNP and I didn't pick it out of thin air.

May have to remain a mystery until someone can find one of these units
to look at. The owner has since given it away unfortunately.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
On 17 Nov 2003 08:10:44 -0500, Sam Goldwasser <sam@saul.cis.upenn.edu>
wrote:

nospam <nospam@nospam.invalid> writes:

Sam Goldwasser <sam@saul.cis.upenn.edu> wrote:

I agree it is weird and I need to look into it more closely. I have
tried to contact the owner to see if they can more carefully trace the
relevant portion of the circuit.

Sorry about the incorrect attribution of blame in my other post, I had a
feeling the circuit must have come from a traced PCB.

http://www.repairfaq.org/sam/hwpl1sch.pdf

No, the attribution is more or less correct. I'm the one who traced it
and was bothered by the regulator from the beginning.

It would almost make sense if Q1 were an NPN but that part number is
definitely PNP and I didn't pick it out of thin air.
Click to expand...
The PNP turns the SCR off when the voltage gets to the desired
setpoint. It's fighting the gate pullup resistor.

May have to remain a mystery until someone can find one of these units
to look at. The owner has since given it away unfortunately.
Click to expand...
Actually, it will work OK if the diodes are flipped over. But it's
still kind of weird. The 1N4001s mainly keep from blowing out the base
of the PNP, I think. This circuit looks more fiddled than designed to
me.

John
 
"Oppie" bravely wrote to "All" (17 Nov 03 00:30:18)
--- on the heady topic of "Re: Using 1N4001 as Zener Diode"

Op> From: "Oppie" <oppie1@cloud9.net>

Op> Some designers tend to get totally anal retentive about temperature
Op> compensation.

I've found something about this by experiment. One can use 2 identical
general purpose transistors, one as zener reverse E-B, in the negative
feedback loop from the collector to base of the other transistor, to get
nearly zero tempco over a wide range of temperatures. BUT it only works
when the zener current of the former is about half the collector current
of the latter. I worked out the approximation at the time and it did
track pretty well when testing.

Asimov
******

.... I worked hard to attach the electrodes to it.
 
Watson A.Name - Watt Sun, Dark Remover wrote:
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf
Click to expand...
I am very rusty in this, but I seem to recall, that an PNP transistor
operated as an NPN has a very low Von (as compared to a "normal"
coupled/biased NPN transistor) when used as a saturated switch.

So if this is the case my suggestion is.

When the capacitors reach full charge the Q1 is driven on preventing the
SCR form firing.

The only thing I miss is R4 to be connected to the cathode of the SCR in
order to provide a ground path for the Q1 base current.

/John
 
John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:
This circuit looks more fiddled than designed to me.

John
Click to expand...
I think that there are more "Fiddled Than Designed" circuits in use
than most of us would dare to believe.
A few years ago I was repairing switchmode DC-DC power converters
made by a US company I won't mention, which use a 555 at the centre of
a mass of components to control the switching. As time went on, I got
more and more certain that probably no-one ever knew how how they
really worked. There was just no logic to it. They'd just added more
and more components until they got the result they were after. Of
course I could be mistaken. :)
Some of the older Panasonic VCRs have circuitry which seems to be
ridiculously complex for what it actually does, too.

Bob
 
In news:3fb93a27$0$171$edfadb0f@dread11.news.tele.dk (John Damm Sřrensen):
Watson A.Name - Watt Sun, Dark Remover wrote:
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf




I am very rusty in this, but I seem to recall, that an PNP transistor
operated as an NPN has a very low Von (as compared to a "normal"
coupled/biased NPN transistor) when used as a saturated switch.

So if this is the case my suggestion is.

When the capacitors reach full charge the Q1 is driven on preventing the
SCR form firing.

The only thing I miss is R4 to be connected to the cathode of the SCR in
order to provide a ground path for the Q1 base current.

/John
Click to expand...

Someone should just build the thing, and test it.

: )
 
"Bob Parker" <bobp@bluebottle.com> wrote in message
news:sreirv4evke7t9f99s4kg2h4jvthu01ssc@4ax.com...
John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:
This circuit looks more fiddled than designed to me.

John

I think that there are more "Fiddled Than Designed" circuits in use
than most of us would dare to believe.
A few years ago I was repairing switchmode DC-DC power converters
made by a US company I won't mention, which use a 555 at the centre of
a mass of components to control the switching. As time went on, I got
more and more certain that probably no-one ever knew how how they
really worked. There was just no logic to it. They'd just added more
and more components until they got the result they were after. Of
course I could be mistaken. :)
Some of the older Panasonic VCRs have circuitry which seems to be
ridiculously complex for what it actually does, too.

Bob
Click to expand...
I'll see your Panasonic and raise you one H.P. ;-)
 
"Mark Jones" <127.0.0.1> wrote in message
news:BoidnQgwabFboiSiRVn-jA@buckeye-express.com...
In news:3fb93a27$0$171$edfadb0f@dread11.news.tele.dk (John Damm Sřrensen):
Watson A.Name - Watt Sun, Dark Remover wrote:
This is an interesting schematic. I hadn't noticed this one before on
Sam's website. Apparently the two 1N4001s are connected in series to
be used as two zener diodes. Why not use a single 1N4002? Maybe to
hand select for the right combination of the two to give the total
breakdown voltage. I'm guessing about 150V each. Never tried it,
tho.

http://www.repairfaq.org/sam/hwpl1sch.pdf




I am very rusty in this, but I seem to recall, that an PNP transistor
operated as an NPN has a very low Von (as compared to a "normal"
coupled/biased NPN transistor) when used as a saturated switch.

So if this is the case my suggestion is.

When the capacitors reach full charge the Q1 is driven on preventing the
SCR form firing.

The only thing I miss is R4 to be connected to the cathode of the SCR in
order to provide a ground path for the Q1 base current.

/John


Someone should just build the thing, and test it.

: )
Click to expand...
I tried to simulate it in Spice and the computer started to smoke :)
 
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