Circuit to change sine wave into square wave

Circuit to change sine wave into square wave. Please quote separately for both stages, although I may not want stage 2 finalizing at this moment. STAGE 1 1) Detect AC high voltage ~1000Vrms in coil. 2) Isolate from following cct. with an optocoupler. 3) Use optocoupler output to generate TTL square wave output of same frequency in phase but with adjustable duty cycle (~5-100%). 4) Provide output suitable to drive H-bridge module (as link) [login to view URL] and stipulate correct wiring into H-bridge to drive a coil. STAGE 2 1) Incorporate a three way switch for user to select:- a) positive half cycle b) positive and negative half cycles c) negative half cycle 2) Enable user to select the square output to be 180deg. out of phase with input.