# Zener Diode Test Ckt

Discussion in 'The Projects Forum' started by leocircuits, Sep 2, 2016.

1. ### leocircuits Thread Starter New Member

Mar 15, 2016
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Looking to Build a Zener Diode Voltage Tester.

I have a Bag of Zener Diodes, I would like to Test there Wking Voltage & Label
them for Future Use......

2. ### #12 Expert

Nov 30, 2010
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7,313
Find a voltage supply, calculate a resistor to allow about 20 ma, measure some zeners.

3. ### SLK001 Well-Known Member

Nov 29, 2011
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Quick and dirty solution:

absf likes this.
4. ### absf Senior Member

Dec 29, 2010
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That's how I test my unknown zeners too. Allen

5. ### crutschow Expert

Mar 14, 2008
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If you have a supply that has a current limit control, then set the current to 20mA at it's maximum voltage setting and then you don't have to adjust the supply for any differences in the voltage of the zeners being tested.

6. ### leocircuits Thread Starter New Member

Mar 15, 2016
7
0
I love the ckt, Very Simple to Build,,...

Apr 5, 2008
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Hello,

You could also use a constant current source.
http://www.dddac.de/at05.htm

Put the zener on the output of the constant current source and measure the voltage accross the zener.

Bertus

dl324 likes this.
8. ### hp1729 Well-Known Member

Nov 23, 2015
2,088
232
I agree with the variable voltage source. Start low and bring up the voltage until you reach 20 mA. (Monitor the voltage across the resistor to determine current.)
Track voltage across the Zener and current through it and compare that curve to other known Zener diodes. A good lesson here in that you can tweak the current through the diode to get a precise voltage.

Nov 4, 2008
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