signal powered dynamic compressor

Mains frequency is often used as a reference for digital clocks and other digital circuits. Unfortunately problems can arise if the `raw` mains waveform is used without further processing, especially when drivi.ng clocks or other timing circuits, as mains transients can cause extra, unwanted counts to occur. The circuit described here will accept a half- or full-wave rectified mains input and provide a 50 or 100 Hz square- wave output, free from interference and suitable for driving CMOS or TTL logic circuits.