this might be super basic but for a geologist it is killing me. I need a low voltage AC device (specifically a dog training collar) to wire to a flashlight so when the remote is pressed the light turns on.

Would a relay (SPST) do this or a MOSFET or??

I have 2 wires off the terminals on the shock collar that output 2V AC at about 2000 uA.

The flashlight has a lead off the batteries to a manual switch. This component needs to replace that manual switch. I am pretty sure every action movie out there uses this scenario .. Lol

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    \$\begingroup\$ I expect some people here to get upset by the fact you are using the shock collar.. There were precedents. \$\endgroup\$ – Eugene Sh. Feb 28 '18 at 20:36
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    \$\begingroup\$ Provide a description of how you made the AC voltage and current measurements. What kind of tools? How were those tools applied? (This is a shock collar question and I think we need to be sure of things.) Also, what is the stated purpose of those two terminals that seem to be provided on this shock collar? \$\endgroup\$ – jonk Feb 28 '18 at 20:37
  • \$\begingroup\$ @EugeneSh. in his defence.. he did not say it was on a dog ;D \$\endgroup\$ – Trevor_G Feb 28 '18 at 20:39
  • \$\begingroup\$ Lol. The shock collar is not on a dog. I had one laying around and thought of it being a "free" remote control device. The multimeter indicates the voltage off of the 2 terminals on the shocking device. FWIW a 4KV cattle prod hurts worse 😂 \$\endgroup\$ – Brett H Feb 28 '18 at 20:52

You can take the AC and peak detect it to turn on a logic level MOSFET. Size R1 to adjust the turn on and turn off delay according to the frequency of the signal.

I'm concerned your AC voltage may be a lot higher than your meter is showing you though, so I added a 5.1V zener, D2, to protect the MOSFET.

HOWEVER : If the output you are measuring is the shock voltage, it will be in the killo-volts range so don't even think about hooking this up.


simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Thanks Trevor! I am pretty sure it is just in the 2V range since it is coming off a 3V Li-ion battery and it doesn't appear to have capacitors in it. My cattle prod tests at 4KV when depressed. Fortunately my MM has a 4KV MAX ( I noticed AFTER I tested it😂) \$\endgroup\$ – Brett H Feb 28 '18 at 21:05
  • \$\begingroup\$ @BrettH these things usually are simple switched inductors though. The kickback voltage is what gives you the shock, and will be a short but large voltage. Basically the same thing as fires the spark plugs in your car. \$\endgroup\$ – Trevor_G Feb 28 '18 at 21:06
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    \$\begingroup\$ The kick WILL be in the kilovolt range as Trevor says ... probably too short for a multimeter, but unpleasant for dogs, fatal for MOSFETs. \$\endgroup\$ – Brian Drummond Feb 28 '18 at 21:16
  • \$\begingroup\$ Ahh thanks for the heads up. So in your proposal the 9V light is isolated from the shock collar current, right? \$\endgroup\$ – Brett H Feb 28 '18 at 21:16
  • \$\begingroup\$ @BrettH they need to share a common ground. If you want it isolated things get more complicated and you need a power source on both sides. \$\endgroup\$ – Trevor_G Feb 28 '18 at 21:17

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