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Zener confusion

Wil

Jan 22, 2017
3
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Jan 22, 2017
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Hi Guys, need some help to identify a zener diode.
Only markings on it is 15-3 ST all I can derive from this is 15.3V from ST electronics,
although my local electronics shop assures me it's a 3V.
Included some pics, if someone might no if this component please help.

Zener1.JPG

Zener2.JPG


[mod note: resized oversized images]
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
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25,510
If it's still working you can test it by getting a couple of 9V batteries and a 10k resistor.

Place them all in series (including your mystery diode) and measure the voltage across the diode. Turn the diode around and read it again.

One way should measure under a volt, the other way will read 3V, 15V, or about 18V.

If it reads 18V then it is either not a zener, or it has a voltage greater than your batteries can provide. Otherwise you will have found the breakdown voltage.
 
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Wil

Jan 22, 2017
3
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Jan 22, 2017
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3
Thanks Steve, will give it a go and report back.
 

Wil

Jan 22, 2017
3
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Jan 22, 2017
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3
Ok, here is my results.
Connected a 9V that's been drained a bit with a reading of 7.9V, after connecting circuit
voltage reading was 7.9V.
So definitely not a 3V :mad:
Added another 9V battery and value went up to 16.8V, but zener clamped voltage at 15.04V.
Used two fresh batteries with value of 18.91V and still clamped voltage at 15.07V.
So in conclusion ( thanks for the help Steve ) definitely a 15V Zener.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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Yep. Very well done :)
 
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