I've recently posted the following instructables:
1) Modifying the output Voltage of an Adjustable AC-to-DC Converter
http://www.instructables.com/id/Modifying-the-output-Voltage-of-an-Adjustable-AC-t
2) Hall Throttle Control of an RC Motor ECS
http://www.instructables.com/id/EBike-Throttle-Control-of-an-RC-Motor-ECS
3) Telephone Ringer Visual Alert (LED)
http://www.instructables.com/id/Telephone-Ringer-Visual-Alert-LED