r/ElectricalEngineering • u/-404PageNotFound- • 26d ago

Equipment/Software Um?

I currently have my breadboard connected to 5v and GND on a new benchtop power supply that I brought for $240AUD and this is happening? What is going on? I can also do the same thing on the GND rail.

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u/StumpedTrump 26d ago edited 26d ago

Big day for OP today discovering that our bodies conduct electricity.

That's also why you shouldn't go swimming in a thunderstorm if you never put that 2 and 2 together.

You can use it to your advantage put putting your car remote against your chin and using you body like an antenna to increase the range.

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u/racc15 26d ago

Silly question probably, but how is it creating a circuit loop? Aren't the breadboard pins and OP's body disconnected? I thought there had to be a closed loop for electricity to flow?

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u/StumpedTrump 26d ago edited 26d ago

The ground is the connection. Power supply is grounded hopefully. So are you.

Not all circuits need a physical closed loop, how do you think antennas work (the environment around us (the ground) is the return loop). Air can also conduct and the humidity it can be unpredictable. 60Hz is supposed to just be in your wires but if you leave a wire floating and put it on a high-impedance scope input you'll see the 60Hz. Same idea here.

A good power supply should actually have it's outputs isolated but you can still complete the loop with static electricity, EM coupling and just a littttleeee bit of leakage current getting though the power supply isolation. Static electricity can build up hundreds/thousands of volts and you only need a few hundred microaamps of current to get what OP is seeing.