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Old June 4th, 2018, 10:37 AM   #16
cardosocea
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It's a Zener diode... not a diode.

https://en.wikipedia.org/wiki/Zener_diode
https://www.electronics-tutorials.ws/diode/diode_7.html
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Old June 4th, 2018, 11:06 AM   #17
Theboss
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Yes. I meant to say zener diode. My apologies.
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Old June 4th, 2018, 01:25 PM   #18
cardosocea
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That's not what I meant. A Zener Diode is not a normal diode, hence why it doesn't gets connected the same way.
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Old June 4th, 2018, 11:31 PM   #19
Pete.S.
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Quote:
Originally Posted by cardosocea View Post
That's not what I meant. A Zener Diode is not a normal diode, hence why it doesn't gets connected the same way.

A diode is like a one-way street, current can only go in one direction.

A zener diode will work as a normal diode in one way so current can pass.
In the other way however it will pass current as well but only if the voltage is large enough.

So a 10 Volt zener diode will let current pass in one direction without a problem and in the other direction when the voltage is over 10 Volt.

This is called the zener breakdown voltage and you can buy different zener diodes with different voltages.

Last edited by Pete.S.; June 4th, 2018 at 11:33 PM.
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Old June 5th, 2018, 12:51 AM   #20
GaryS
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Keep in mind Zener diodes are always reversed biased
in forward bias they act just like a regular diode
I have seen them called breakdown diodes because the reverse barrier braked down and conducts at the set voltage. They become shorts with any voltage above the breakdown voltage. they can dissipate very little power before they destroy then selves. .
I think a correctly sized MOV will work better for you.
but if you really want proception use a signal isolator thy can give you several thousand volts of isolation I think they would be your best option.
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Old June 5th, 2018, 01:33 AM   #21
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Thank you guys for your replies, just to clarify. If you apply +12 vdc on the cathode(negative) of the zener diode with a zener breakdown of 10 v dc, it will conduct current?
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Old June 6th, 2018, 06:50 PM   #22
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Zener Diodes are used in conjunction with a fuse and a current limiting resistor to create an intrinsically safe barrier. Multiples are used for safety (typically 3) and the design intent is to short to ground at it's threshold so that the fuse clears the fault before any sparking damage can happen at the hazardous area.
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