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Can I use a mini jack to power things up? Answered

Hi, first of all I must apologize if I'm not being clear on the description of what I'm planning on doing (english is not my first language), there's a drwing if it can help understand what i'm trying to say.
So here's my "problem":

I have been building several devices (small LED lamps, robots and other geeky stuff I found here on Instructables) and I'm trying to find a good and "universal" solution to power them. Their energy consumption is low so I decided I could use a USB connection as the power source/supply.
Now, I would like to use a single cable to power all these, a "plug and play" solution and I've been thinking to jacks, the kind you find on headphones: easy to plug/unplug and I've got plenty of spare female jack plugs I can use with the devices (with the appropriate resistors included).

So basically I would end up using a cable with a male USB on one end and a male mini jack on the other.

Is it possible to use the jacks this way?
Will the mini jacks and/or the headphones cables stand the power from a USB source?

Thanks for your answers!

Discussions

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frollard

8 years ago

Yes it will work, just be careful with how you wire the jack:

You want the ground (- connection) to go to the RING, at the base of the mini jack, and you want the +5v to go to the very tip - then its less likely you'll short out the connection.  The computer's usb port SHOULD be connected from short circuit, but I've wrecked more than a few by shorting things out. 

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benjigoldfrollard

Answer 8 years ago

Thanks for your answer (it also applies to the others! Now I know with certainty the USB port can provide 5V :-) ). I should not overload my USB since I'm mostly using small LEDs (2 max) or small circuit boards.

But now I have a new question:
You (frollard) raised the matter of the "ground wire". From my memories of electronics in school, the ground is used as a protection against short circuits by diverting the electricity caused by a miswiring to....the ground where it's rendered harmless for the device components.

But on a USB there are only 4 wires: 2xData, 1 positive and 1 negative. Where do I  solder my ground wire from the jack?

Again: thanks!

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frollardbenjigold

Answer 8 years ago

*in general* but not always the voltages will be marked.  If something is +5v that's 5 volts ABOVE ground (zero).  Computer power supplies have a negative ground, so the +5, +12 are above ground volts, where the current flows from +5 to ground (the electrons flow the other way, but thats electrical engineering for you, being invented before electrons were common knowledge, and 'doing it wrong' stuck.)

Computer psu's also usually have a -12 rail, so you have -12, ground, +5, and +12 volts.  hooking -12 to +12 in a circuit would yeild 24 volts...etc.

So again; generally things are negative ground - but always check with a multimeter.

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RavingMadStudios

8 years ago

Yes, and your English is considerably better than many of the native speakers who post here. Thanks for that.

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Burf

8 years ago

Yep, that will work, done it myself. So long as your appliances can be powered by the five volts carried by the USB, that will work.

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Re-designBurf

Answer 8 years ago

And don't overload the usb port on the computer.