The UNO has some great advantages for people starting out and playing around, but the 5v/40ma output power limit can be a bit limiting without additional circuitry. While the UNO is not intended to drive anything directly, it kind of defeats the purpose if you have to hunt through and source a bunch of stuff to attach to do anything. As a result, there are a number of boards available. However, I wanted to build a board for the uno that had a lot of power control options, which didn’t seem to exist. The first thing I wanted to put on was a Darlington array.

Relevant portions of the board for the darlington array shown highlighted.

I think the arduino motto is “cheap, quick, and dirty,” and the darlington array certainly fits that. This setup allows eight outputs of either VIN or 5V at 500mA each and is used under the assumption that you don’t need to worry about response times or anything like that. If you did, they you really might want to choose something other than a $5 UNO board.

The magenta (D10-13) and fuchsia (A0-3)  headers are intended to control the darlington (blue headers) via jumpers.

The read header is connected to one of the yellow headers to supply voltage (5V or VIN) to the array.

The orange headers provide output power and are conveniently located next to ground headers in green.

Parts of the schematic relevant to the darlington are shown highlighted in colors as used above.

And, it would appear wordpress is shrinking my images by just a bit because of borders. I did not notice that before *sigh* I guess I need to hunt through the css and see what I did…