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Author Topic: Electrical question?  (Read 1580 times)

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Offline pixelpusher

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Electrical question?
« on: Tue, 31 January 2017, 08:25:10 »
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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Offline need

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Re: Electrical question?
« Reply #1 on: Tue, 31 January 2017, 08:38:50 »
I'm not sure man.
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Offline fohat.digs

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Re: Electrical question?
« Reply #2 on: Tue, 31 January 2017, 08:51:48 »
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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That's the message. That's the whole message. Say that every day, not just to reach America's frustrated young white men, but people of every age, race, and gender.
Late-stage capitalism is a wealth-concentration engine, focused on vacuuming up every dollar and putting it in as few hands as possible. Republicans are helping that vacuum suck.
How does a tiny fraction of the population get away with this? They do it by dividing the other 99% of Americans against themselves."
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Offline pixelpusher

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Re: Electrical question?
« Reply #3 on: Tue, 31 January 2017, 08:56:07 »
Quote from: fohat.digs on Tue, 31 January 2017, 08:51:48
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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Offline fohat.digs

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Re: Electrical question?
« Reply #4 on: Tue, 31 January 2017, 09:17:58 »
Yes, and: where would it get off after "flowing through" you?
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"However, even though I was born in the Mesozoic, I do know what anyone who wants to reach out to young people should say: Billionaires took your money. They took your chance to buy a home. They took your chance at a good education. They stole your opportunities. Billionaires took the things you want in life. If you really want those things, you have to take them back.
That's the message. That's the whole message. Say that every day, not just to reach America's frustrated young white men, but people of every age, race, and gender.
Late-stage capitalism is a wealth-concentration engine, focused on vacuuming up every dollar and putting it in as few hands as possible. Republicans are helping that vacuum suck.
How does a tiny fraction of the population get away with this? They do it by dividing the other 99% of Americans against themselves."
- Marc Sumner 2025-05-30

Offline OfTheWild

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Re: Electrical question?
« Reply #5 on: Tue, 31 January 2017, 09:57:06 »
The simple answer is electricity takes the path of least resistance. And you're a poor conductor.
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Offline pixelpusher

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Re: Electrical question?
« Reply #6 on: Tue, 31 January 2017, 10:01:19 »
Quote from: OfTheWild on Tue, 31 January 2017, 09:57:06
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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Offline fohat.digs

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Re: Electrical question?
« Reply #7 on: Tue, 31 January 2017, 10:36:21 »
Think of all the birds that you have seen clutching 500KV overhead lines carrying thousands of amps.
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"However, even though I was born in the Mesozoic, I do know what anyone who wants to reach out to young people should say: Billionaires took your money. They took your chance to buy a home. They took your chance at a good education. They stole your opportunities. Billionaires took the things you want in life. If you really want those things, you have to take them back.
That's the message. That's the whole message. Say that every day, not just to reach America's frustrated young white men, but people of every age, race, and gender.
Late-stage capitalism is a wealth-concentration engine, focused on vacuuming up every dollar and putting it in as few hands as possible. Republicans are helping that vacuum suck.
How does a tiny fraction of the population get away with this? They do it by dividing the other 99% of Americans against themselves."
- Marc Sumner 2025-05-30

Offline OfTheWild

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Re: Electrical question?
« Reply #8 on: Tue, 31 January 2017, 10:44:41 »
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.
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-Dana
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