Fence tester - which resistors? (discuss.tchncs.de)

submitted 2 years ago by crashez@discuss.tchncs.de to c/askelectronics@discuss.tchncs.de

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I lost my electric fence tester, probably the pigs ate it. But I opened it once to resolder the earth wire and found it's really just a voltage divider with resistors and leds, so I can probably rebuild with stuff I have. What resistor values though? 2k to 10k V run through the fence. If any of you good people have a diagram, a formula or an idea, please help.

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[-] jjagaimo@lemmy.one 2 points 2 years ago* (last edited 2 years ago)

In the Wikipedia page there's this formula

Just plug in values for the fence voltage and led. You can just set vswitch to 0 and Vled to 2V. It should be fairly insignificant compared to the fence voltage. It should be 10-20mA (0.01-0.02) to not kill the led.

The root of this is Ohms law: V=IR. Diodes cause a voltage drop rather than directly acting like a resistor which is why it's subtracted from the input voltage.

Just put them in series. Make 2x, one in each direction to account for AC and DC

this post was submitted on 06 Jul 2023

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