Ask Electronics

3259 readers

1 users here now

For questions about component-level electronic circuits, tools and equipment.

Rules

1: Be nice.

2: Be on-topic (eg: Electronic, not electrical).

3: No commercial stuff, buying, selling or valuations.

4: Be safe.

founded 1 year ago

MODERATORS

DavideAndrea@discuss.tchncs.de

linker3000@discuss.tchncs.de

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

submitted 1 year ago by crashez@discuss.tchncs.de to c/askelectronics@discuss.tchncs.de

9 comments fedilink hide all child comments

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.

you are viewing a single comment's thread
view the rest of the comments

[–] jjagaimo@lemmy.one 2 points 1 year ago* (last edited 1 year 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