When my brother built his EL84 amplifier he wanted to be able to count on/off operations and how long the amplifier had been running, and we came up with this clever on/off and hour counter in both an AC and a DC version based on a PIC16F628A and a seven segment LED display.
Click on the picture to enlarge it and read our comments and advice
The finished project based on a PIC16F628A and a seven segment LED showing firmware version, on/off operations and total on time.
Projects files:
Click on the picture to enlarge it and read our comments and advice
Projects files: