Using 1N4001 as Zener Diode

[Jim Thompson]

On Mon, 17 Nov 2003 22:15:02 +0100, John Damm Sřrensen
<john-nospam@nomail.hovedpuden.dk> wrote:

[snip]

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.

[snip]

You're confusing inverted-mode (swap emitter and collector
connections) with "PNP transistor operated as an NPN", which can't be
done.

See "InvertedTransistors(Hunter).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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[John Damm Sřrensen]

Jim Thompson wrote:

On Mon, 17 Nov 2003 22:15:02 +0100, John Damm Sřrensen
john-nospam@nomail.hovedpuden.dk> wrote:

[snip]

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.


[snip]

You're confusing inverted-mode (swap emitter and collector
connections) with "PNP transistor operated as an NPN", which can't be
done.

See "InvertedTransistors(Hunter).pdf" on the S.E.D/Schematics page of
my website.

...Jim Thompson
Well of course I am.

/John

 

[Sam Goldwasser]

"Mark Jones" <127.0.0.1> writes:

Someone should just build the thing, and test it.

: )

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

Someone who has one of these things should just remove the lid and check.

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Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.

 

[Ross Mac]

"David" <dkuhajda@locl.net.spam> wrote in message
news:3fb80f86@news.greennet.net...

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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You have to wonder why they did not use an 11 volt zener instead of a 10

volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet on
that SCR but perhaps it needed a little more voltage....guess I will have to
study this one a bit more too....Ross

 

[John Popelish]

Bob Parker wrote:

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

That approach is now glorified with the name, "evolutionary design".

--
John Popelish

 

[Ross Mac]

"EEng" <unmaileeng@budget.net> wrote in message
news:gaqfrvgb77lt3guc0qf6sf588nef6hlc1b@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


Looks like a reverse blocking 11.4V Zener to me.
I agree...It kind of looks like a custom zener!....Ross

 

[Ross Mac]

"Baphomet" <fandaDEATH2SPAMMERS@catskill.net> wrote in message
news:vrigrqjvtsku7c@corp.supernews.com...

"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.

: )

I tried to simulate it in Spice and the computer started to smoke


You know Baphomet, a bunch of us may end up in the garage tonight simulating

this damm thing...it should be simple....famous last words!.....Ross

 

[Jim Thompson]

On Mon, 17 Nov 2003 23:21:31 GMT, "Ross Mac"
<macroeng@example.invalid> wrote:

[snip]

You have to wonder why they did not use an 11 volt zener instead of a 10
volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet on
that SCR but perhaps it needed a little more voltage....guess I will have to
study this one a bit more too....Ross

Could be for TC reasons. Zeners above 5V have a positive TC, diodes
have a negative TC.

...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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Ross Mac]

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:3emirv4qcpfnho6dc41n1m86c85fabvkkr@4ax.com...

On Mon, 17 Nov 2003 23:21:31 GMT, "Ross Mac"
macroeng@example.invalid> wrote:

[snip]

You have to wonder why they did not use an 11 volt zener instead of a 10
volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet on
that SCR but perhaps it needed a little more voltage....guess I will have
to
study this one a bit more too....Ross


Could be for TC reasons. Zeners above 5V have a positive TC, diodes
have a negative TC.

...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 |

I love to cook with wine. Sometimes I even put it in the food.
It sounds to me like you hit the nail on the head Jim....since this device

most probably gets pretty warm under heavy use it makes a lot of sense. And
hey, I found it for 18 bucks at a camera shop. I also found a link that
somewhat speaks exactly to your comment.....good one...that one went right
past me....here is the link... http://www.microsemi.com/micnotes/205.pdf
And hey, I like to cook with wine too....on mushrooms
especially....yummmm.....Ross

 

[John Larkin]

On Tue, 18 Nov 2003 08:28:33 +1100, Bob Parker <bobp@bluebottle.com>
wrote:

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

We need an archival web site, StunninglyBadElectronicDesigns.com.

Hey, a google of 'bad design' has some cool hits, like

http://www.baddesigns.com/examples.html

John

 

[Jim Thompson]

On Tue, 18 Nov 2003 00:20:00 GMT, "Ross Mac"
<macroeng@example.invalid> wrote:

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:3emirv4qcpfnho6dc41n1m86c85fabvkkr@4ax.com...
On Mon, 17 Nov 2003 23:21:31 GMT, "Ross Mac"
macroeng@example.invalid> wrote:

[snip]

You have to wonder why they did not use an 11 volt zener instead of a 10
volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet on
that SCR but perhaps it needed a little more voltage....guess I will have
to
study this one a bit more too....Ross


Could be for TC reasons. Zeners above 5V have a positive TC, diodes
have a negative TC.

...Jim Thompson
[snip]
It sounds to me like you hit the nail on the head Jim....since this device
most probably gets pretty warm under heavy use it makes a lot of sense. And
hey, I found it for 18 bucks at a camera shop. I also found a link that
somewhat speaks exactly to your comment.....good one...that one went right
past me....here is the link... http://www.microsemi.com/micnotes/205.pdf
And hey, I like to cook with wine too....on mushrooms
especially....yummmm.....Ross

My rule-of-thumb for zeners, while not perfect, is fairly close:

TCz = (Vz-5)mV/°C

for diodes:

TCd = -2mV/°C

I have a *little* experience in that area: At Motorola, in the '60's,
my nickname was vBE-Thompson, since I fixed everything with diodes. I
even have some patents on TC-ing alternator regulators.

Mushrooms in wine sauce over filet = To Die For ;-)

...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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Ross Mac]

"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:slpirv44qt0vi5pok5s599mml5n8bs5ojl@4ax.com...

On Tue, 18 Nov 2003 00:20:00 GMT, "Ross Mac"
macroeng@example.invalid> wrote:


"Jim Thompson" <invalid@invalid.invalid> wrote in message
news:3emirv4qcpfnho6dc41n1m86c85fabvkkr@4ax.com...
On Mon, 17 Nov 2003 23:21:31 GMT, "Ross Mac"
macroeng@example.invalid> wrote:

[snip]

You have to wonder why they did not use an 11 volt zener instead of a
10
volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet
on
that SCR but perhaps it needed a little more voltage....guess I will
have
to
study this one a bit more too....Ross


Could be for TC reasons. Zeners above 5V have a positive TC, diodes
have a negative TC.

...Jim Thompson
[snip]
It sounds to me like you hit the nail on the head Jim....since this
device
most probably gets pretty warm under heavy use it makes a lot of sense.
And
hey, I found it for 18 bucks at a camera shop. I also found a link that
somewhat speaks exactly to your comment.....good one...that one went
right
past me....here is the link... http://www.microsemi.com/micnotes/205.pdf
And hey, I like to cook with wine too....on mushrooms
especially....yummmm.....Ross


My rule-of-thumb for zeners, while not perfect, is fairly close:

TCz = (Vz-5)mV/°C

for diodes:

TCd = -2mV/°C

I have a *little* experience in that area: At Motorola, in the '60's,
my nickname was vBE-Thompson, since I fixed everything with diodes. I
even have some patents on TC-ing alternator regulators.

Mushrooms in wine sauce over filet = To Die For ;-)

...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 |

I love to cook with wine. Sometimes I even put it in the food.
Thanks for the formulas, I figured you must be the diode man to know them so

intimately....
......and hey...mushrooms in wine and butter sauce spread over a
filet...can't argue that formula either....I better put the potatoes on now!
I guess I will be off to the kitchen to prepare a meal for the football game
tonight....thanks for the tips Jim, Ross

 

[Jim Weir]

Jim...

We went through a long song and dance to show that the crossover from -tc to +tc
was just a bit above 6 volts (in 1966). Have things dropped to 5 volts now?

Jim


Jim Thompson <invalid@invalid.invalid>
shared these priceless pearls of wisdom:


->
->Could be for TC reasons. Zeners above 5V have a positive TC, diodes
->have a negative TC.
->
-> ...Jim Thompson

 

[Jim Thompson]

On Mon, 17 Nov 2003 17:35:59 -0800, Jim Weir <jim@rst-engr.com> wrote:

Jim...

We went through a long song and dance to show that the crossover from -tc to +tc
was just a bit above 6 volts (in 1966). Have things dropped to 5 volts now?

Jim


Jim Thompson <invalid@invalid.invalid
shared these priceless pearls of wisdom:


-
->Could be for TC reasons. Zeners above 5V have a positive TC, diodes
->have a negative TC.
-
-> ...Jim Thompson

That's just my old rule-of-thumb. 6V works even better with the OP's
circuit ;-)

...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 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Tim Williams]

"John Larkin" <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote in
message news0pirv8jaqql2ofqnm5c34ne7dp7op8mo3@4ax.com...

Hey, a google of 'bad design' has some cool hits, like

http://www.baddesigns.com/examples.html

Boy that guy is really bad at taking a good LOOK...

Tim

--
"That's for the courts to decide." - Homer Simpson
Website @ http://webpages.charter.net/dawill/tmoranwms

 

[Bob Parker]

John Popelish <jpopelish@rica.net> wrote:

That approach is now glorified with the name, "evolutionary design".

I thought it was called "empirical clairvoyance"....

Bob

 

[Mark Mcmillan]

"John Damm Sřrensen" <john-nospam@nomail.hovedpuden.dk> wrote in message
news:3fb93a27$0$171$edfadb0f@dread11.news.tele.dk...

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

If that's the case and the diodes were reversed then the SCR would be
prevented from firing until the 120Hz DC ripple voltage was ~ 12V below the
voltage of C1a times the ratio of R3/R3+R4..?
Or perhaps the idea is to keep the SCR off when the voltage drop from the
gate to C1a is grater the XXX volts to prevent the SCR from supplying
current to the flash tube after the caps are discharged..?
Keep in mind the time constant of R1 X C2.

M2

 

[Rich Grise]

[old news, stupid sigs, and angle bracket pyramids, left behind by
string of
bottom-feeder^H^H^H^H^H^Hposters, snipped]

The 1N4001s are there to temperature-compensate the zener. They have
opposite
temperature coefficients, but WAGing from the circuit, I'd say that the
zeners TC is probalby closer to -2x the 1N4001's than -1x. And what the
transistor's for is to amplify current. And the diodes NEVER have more
than
a forward diode drop across them in the forward direction (albeit that
drop
might get up to some volts before the diode explodes) until they open.
The
whole string conducts. I'll have to look at the circuit more to say any
more;
I didn't memorize it yet! ;-D

Cheers!
Rich

You have to wonder why they did not use an 11 volt zener instead of a 10
volt and 2 1N4004's, unless the additional .2 to .4 volts were
important....which I can't see right now....I don't have a data sheet on
that SCR but perhaps it needed a little more voltage....guess I will have to
study this one a bit more too....Ross