The brief from the customer was to simulate the functions of an existing timer that wasn't accurate over longer time intervals. It soon became clear that very little extra effort or components would be required to make the new board into a dual timer so this was done. Most of the timers will be single channel so those additional components aren't fitted.

 

A PIC microprocessor was used and programmed in Assembler. An additional feature was added to allow one timer to trigger the other in software. The DIP switches are used to program the timers.

 

The customer uses his own low cost ICD2 module and a simple circuit board with a ZIF socket to program the microprocessor himself. 

 

The circuit was drawn as a schematic and converted into the layout shown using Seetrax Ranger XL software.