What is the Average Defect Rate for Zeners?

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

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I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS, and went thru all 100 zeners to see wha their Vz
was. Most were in the 5.6 to 5.75V range, but then I got the
following:

5.5V
5.49V
5.48V
Above are still within the 5.32V minimum for 5% zeners.

The following are borderline, or out of tolerance.
5.33V
5.26V
5.25V
4.9V
1.24V defective

Which is why I ask the Q, how many of the zeners should I expect to be
defective? I have one that's clearly so low it's defective. The
other four are out of tolerance. That's about a 5% defect rate, I'd
say.

Thanks.
--
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Don't be ripped off by the big book dealers. Go to the URL
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@@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@@
 
On Mon, 29 Dec 2003 11:53:17 -0800, Watson A.Name - "Watt Sun, Dark
Remover" <alondra101@hotmail.com> wrote:

I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS
Click to expand...
Perhaps your PS contains an internal capacitor on the output
terminals? It's charge could have destroyed the diodes. A safer method
IMHO would be to set the output voltage to 12V (for example) and use
an external current limiting resistor of ca. 240ohm.
I'm only guessing...

Piotr
 
In article <s071vv0bjjmm60pg613flqt0r44ftt9adt@4ax.com>,
piotr433@pisi.com.pl mentioned...
On Mon, 29 Dec 2003 11:53:17 -0800, Watson A.Name - "Watt Sun, Dark
Remover" <alondra101@hotmail.com> wrote:


I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS

Perhaps your PS contains an internal capacitor on the output
terminals? It's charge could have destroyed the diodes. A safer method
IMHO would be to set the output voltage to 12V (for example) and use
an external current limiting resistor of ca. 240ohm.
I'm only guessing...

Piotr
Click to expand...
Thanks for pointing me to a possible problem that I hadn't thought
about. There might be a small electrolytic across the output. But I
checked all 100 of them without problems, except for the single
defective one, so I'm thinking that it wasn't caused by a discharge.

One problem with using a resistor is that the current isn't truly
constant. But that shouldn't be a problem in this case.

Thanks again.
--
@@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@@
 
The 1.24 Volt "defective" Zener may be incorrectly banded. Try reversing
the voltage!


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

I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS, and went thru all 100 zeners to see wha their Vz
was. Most were in the 5.6 to 5.75V range, but then I got the
following:

5.5V
5.49V
5.48V
Above are still within the 5.32V minimum for 5% zeners.

The following are borderline, or out of tolerance.
5.33V
5.26V
5.25V
4.9V
1.24V defective

Which is why I ask the Q, how many of the zeners should I expect to be
defective? I have one that's clearly so low it's defective. The
other four are out of tolerance. That's about a 5% defect rate, I'd
say.

Thanks.
--
@@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@@
Click to expand...
 
ADOLPHIUS ST. CLAIR wrote:
The 1.24 Volt "defective" Zener may be incorrectly banded. Try reversing
the voltage!


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


I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS, and went thru all 100 zeners to see wha their Vz
was. Most were in the 5.6 to 5.75V range, but then I got the
following:

5.5V
5.49V
5.48V
Above are still within the 5.32V minimum for 5% zeners.

The following are borderline, or out of tolerance.
5.33V
5.26V
5.25V
4.9V
1.24V defective

Which is why I ask the Q, how many of the zeners should I expect to be
defective? I have one that's clearly so low it's defective. The
other four are out of tolerance. That's about a 5% defect rate, I'd
say.

Thanks.
--
@@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@@


Another possibility is dat your power supply has an output capacitor.
Click to expand...
Although the continuous current is limited to 25mA, the capacitor can
cause a current of serveral amps, effectively destroying your zener
diodes. I wouldn't be surprised if you just destroyed all 100....

Good luck
Marco
 
In article <3FF44108.F53DA386@earthlink.net>, nermal1@earthlink.net
mentioned...
The 1.24 Volt "defective" Zener may be incorrectly banded. Try reversing
the voltage!
Click to expand...
I checked, and in the oppoiste direction is has the normal .6V. So
no, it's not misbanded.

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

I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS, and went thru all 100 zeners to see wha their Vz
was. Most were in the 5.6 to 5.75V range, but then I got the
following:

5.5V
5.49V
5.48V
Above are still within the 5.32V minimum for 5% zeners.

The following are borderline, or out of tolerance.
5.33V
5.26V
5.25V
4.9V
1.24V defective

Which is why I ask the Q, how many of the zeners should I expect to be
defective? I have one that's clearly so low it's defective. The
other four are out of tolerance. That's about a 5% defect rate, I'd
say.

Thanks.
--
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@@
 
In article <DG0Jb.498$_x2.38714@zonnet-reader-1>, marco_kr@hotmail.com
mentioned...
ADOLPHIUS ST. CLAIR wrote:
The 1.24 Volt "defective" Zener may be incorrectly banded. Try reversing
the voltage!


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


I bought 100 1N4734A 5.6V Zeners on Ebay for about $5 incl S&H, and
they came still on tape. So I set my PS to 25 mA current, and put a
DMM across the PS, and went thru all 100 zeners to see wha their Vz
was. Most were in the 5.6 to 5.75V range, but then I got the
following:

5.5V
5.49V
5.48V
Above are still within the 5.32V minimum for 5% zeners.

The following are borderline, or out of tolerance.
5.33V
5.26V
5.25V
4.9V
1.24V defective

Which is why I ask the Q, how many of the zeners should I expect to be
defective? I have one that's clearly so low it's defective. The
other four are out of tolerance. That's about a 5% defect rate, I'd
say.

Thanks.
--
@@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@@


Another possibility is dat your power supply has an output capacitor.
Although the continuous current is limited to 25mA, the capacitor can
cause a current of serveral amps, effectively destroying your zener
diodes. I wouldn't be surprised if you just destroyed all 100....
Click to expand...
SOmeone else suggested the same possibility. I checked the PS and it
has a 20 uF across the output. It may have caused excessive current
when I connected the zeners, but the other 99 didn't get zapped by it.
If it did put extra stress in the ZDs, I'm glad that that one failed
when it did, and not later when the diode was in a working circuit.

Thanks.
Good luck
Marco
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@@
 
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