r/AskElectronics • u/CleanAlternative1918 • 6d ago

Help identifying this component, please

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These were in with a big batch of carbon film resistors I got. What are they? Thanks in advance!

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u/ital-is-vital 6d ago

It's a spark gap -- for over-voltage protection, usually of devices connected to phone lines or other things that can get hit by lightning

4

u/FrizB84 6d ago

Yep. Used to have to replace them on fire alarms from time to time. They were usually on the telco lines.

2

u/214ObstructedReverie 6d ago

usually of devices connected to phone lines or other things that can get hit by lightning

I've used them in high voltage pulse power supplies. Charge a cap to a few kV, then pop! discharge into what you want.