geekhack
geekhack Community => Off Topic => Topic started by: pixelpusher on Tue, 31 January 2017, 08:25:10
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Okay, so I test a PCB by touching a paper clip to the holes for each switch with Switchhitter open to show me registered key presses, right?
I've done this for 3 boards now and it's a great tool... however, I just started to wonder why am I not getting electrocuted? Can anyone explain. I'm obviously touching the circuit. I'm thinking the USB connection delivers 5V max to the board, right? Maybe that's not enough to cause a shock?
Sure wish I would have taken some sort of electrical fundamentals courses in college now :(
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I'm not sure man.
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5 volts DC @ 1/2 amp max is not really a lot of current. And you are probably clothed and sitting or standing on a non-conductive floor.
Electricity needs a completed circuit to flow through.
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5 volts DC @ 1/2 amp max is not really a lot of current. And you are probably clothed and sitting or standing on a non-conductive floor.
Electricity needs a completed circuit to flow through.
So it's easier for the electricity to just keep flowing through the paper clip than it is for it to flow through me, maybe?
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Yes, and: where would it get off after "flowing through" you?
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The simple answer is electricity takes the path of least resistance. And you're a poor conductor.
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The simple answer is electricity takes the path of least resistance.
But let's say (hypothetically) the USB connection was supplying something like 120Volts of power. Would I still be perfectly safe touching the paper clip? I've touched enough hot wires in outlets to know that my feet on the floor (with shoes on) is still a perfectly fit path for electricity. Translation: I've electrocuted myself several times on AC outlets.
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Think of all the birds that you have seen clutching 500KV overhead lines carrying thousands of amps.
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if you had a paperclip relative to the amount of imagine it like water through a pipe. There are lots of water analogies that people use to explain watts and volts vs. amps and unfortunately electrical engineers are always the ones trying to explain it. :)) There are a few "ELI5" (explain like i'm 5) posts on reddit about this very subject i'm sure.