I came to an impasse. It’s something we all encounter almost everyday in our workaday lives. How am I going to use my keyboard in the dark and not turn on a lamp? I felt you pain and decided that I needed to do something about it. I really wanted to make it as compact as possible so a reduction of wires was key. Since I had a keyboard with an extra USB port on one side I decided that that was the easiest and most accessible power source.
I did a little research and found that USB outputs 5V @ 100 mA. That seemed like more than I needed to make this project work.
Here is a little circuit and math work. It’s actually a lot easier than it looks.
This is the circuit working on a protoboard being powered by the keyboard.
There is the finished circuit on a cheap Radio Shack circuit board.
I just used some sticky putty to adhere it to the underside of my keyboard trade. You can’t see it without being under the desk so outer housing was not essential.
Here is the finished product! Does its job very well.
Total cost of the projects ran about $20 with LEDs, resistors, and PC board. The USB cable was just one I had lying around in my basement. I have since added a switch as well so I could always leave it plugged in. I don’t know why that didn’t cross my mind until after I built it. Fun little project and very useful.
