A Simple Mind Builds Something That Glows In The Dark

Feeling rather electrical the other day, I finally got around to hooking a LED up to the USB port.

A rather simple project, compared to building a Knight-Kit Star Roamer short-wave receiver (which didn't work...), it only took me an hour to solder the thing together. There are only three parts:

1. Green LED (salvaged from something, no specs)
2. Resister, 220 ohm (Red-Red-Brown-Gold 1/4 watt)
3. Heat shrink tubing
4. Wire, a bit of
5. USB connector and cable (salvaged from Apple mouse)

Wait, that's more than three...

Using my trusty Harbor Freight El Cheapo Brand multimeter (You can build a ECG with one!), I measured the current with the 220 ohm resister as 15 mA (Is that right? Milli amps? Micro amps? I forget!), which seems ok, according to this article it can't exceed 500 mA.

Testing the whole mess was a trial, as I only had one alligator clip to hold things together. I need to rig up a test jig for testing these misc. LEDs I have laying around.

Using some math, I suppose I could have calculated the optimum resister to use, but I felt a headache coming on. After all, the math in this article took me a half-hour to get through my head.

Works great, but I need a white LED to actually do any good, I think.



Why are there two reflections?

Today is Google blackout day, turn out your lights tonight for an hour!