For electric clock using synchronous motor designed for the other frequency vs local mains frequency, some form of frequency conversion is required. It is often not satisfactory to use just a crystal oscillator as one can expect timing error of about 1~4 minute per month, with the changing of ambient room temperature. An AC connected clock will do much better in long term period of months or year as the power company often undertake to correct for any timing error between an AC powered clock and an accurate time source by varying system frequency to compensate. In simple term, the converted frequency must be somehow related/locked to the mains frequency and the clock powered by this frequency will keep time fine as any other clock. There are many possibilities: A. using a single 8-pin PIC - By eblc1388 1. single chip solution, works also for 60Hz into 50Hz 2. standalone 50Hz or 60Hz standard frequency output, crystal accuracy 3. no adjustment required 4. software ensure exact cycles tally. e.g 600 cycle of 60Hz vs 500 cycles of 50Hz YouTube: 50/60Hz Frequency Conversion Using PIC B. Phase locked loop & 600Hz to 60Hz direct conversion - By eblc1388 1. use x6 PLL to get 600Hz square wave from 100Hz 2. use 5-stage ring counter to build staircase waveform(see image below) 3. pass staircase waveform to RC filter to get 60Hz sine wave More information here: post#32 Forum Post#32: frequency multiplier C. Harmonic method - By Rod Elliott 1. Picking out the sixth harmonic of 100Hz (50Hz fullwave rectified) signal 2. amplified and squaring the signal to get 600Hz square wave 3. divide by 10 to get 60Hz square wave 4. pass into active filter to remove all higher harmonic leaving fundamental 60Hz sine wave The link is here: Frequency Changer for Low Voltage Synchronous Clocks The bottom trace is the combined waveform output of the five stage ring counter and the top trace signal after RC filter, mentioned in option B above.