How to make a USB pet rock?

DragonClaw01

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So for Father's Day wanted to make a pet rock for my father.(Yes it will probably be a late gift, I don't expect it to be done just like that) I want to plug in to a USB slot his computer. But I would also like to put a little red LED opposite of the plug that lights up when plugged in. Distance of one end to the other is like 4-6 inches. Even if I have to cannibalize a cheap mouse for the USB or something, what is the way to do this? (note I am drilling a small hole through the rock all the way through.)
 
pretty much any USB cable would work for power delivery, you have a bigger problem with the LED though.
most LED's use something else besides USB's default 5V to work, requiring you to have separate driver for it, this needs space, carving said space into rock might not be easy.
There are some straight off 5V leds:
http://www.ebay.com/itm/U-S-Seller-5pcs-RED-5mm-Pre-Wired-LED-Light-5v-13V-DC-Lamp-Bulb-LED-/112395017790

alternately you can just buy normal LED, single resistor and solder them in series, to get less than 5V on the LED, in that case LED's required voltage determines the resistor value though. Following link has some discussions about that:
https://electronics.stackexchange.com/questions/27561/why-we-use-330-ohm-resistor-to-connect-a-led

you could pretty much reuse any usb cable (or mouse or phone charging cable or something) cut the wire and solder red and black to the LED (red +, black -) and apply some shrink wrap on top, giving you usb powered LED.
 

DragonClaw01

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That's much more complex than I thought. Dang. Okay, what else can it do off of USB? I thought LED would be easy peasy. :eek:
 
LED and resistor is real easy.

About 5mA for the LED (not too bright), 2v forward current is typical, so 3V across the resistor. R=V/I=3/0.005=600Ω or thereabouts. Plus or minus like 30%.

Your resistor is going to be smaller diameter than the LED.
 
anything besides the LED will be "more complex" since you would need to add actual functionality to it, connect it to computer with USB's data cables, write driver for it and have small circuit board to do all that "other" stuff.

Probably easiest of the lot, if you don't want to go to programming would be to reuse a mouse, carve out the rock (not easy at all, rock is kind of... brittle) and reuse all the components to turn said rock into functional mouse.
You most likely wont be able to accomplish that. (I cannot either, rock carving is not in my skill or tool set)
 

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