[Doug] pulls a signal from the 9V AC power before it hits the bridge rectifier ... number of the software displaytime(); // display the current time TMR1H=0xff; TMR1L=MAINS_DLY; // reset TMR1H ...

A great example is this simple wireless AC current detector from [NEW PEW]. The circuit is a simple one, and a classic. The spring from a ballpoint pen is soldered to the base of a BC547 ...