I want to build an automatic voltage regulator(AVR) for 3 phase sinkron generator using mcs-51.

I need to measure the output voltage of the gen-set and compare it wether the voltage is fit with the voltage which I set first.
now I've already steped down the output voltage with 100:1 ratio. then I rectified the sinusoidal signal with full wave rectifier. in order to build a quick stabilizing response, I avoid using a capasitor that will "smooth" the signal to its peak value, because in my opinion it will slow down the detection of the output voltage fluctuation. is it right??

if I have to sampling the signal, where can I get the information to make a sampling circuit?? with op amp??
I've tried to find ADC with sampling and hold facility, but it is not available in indonesia.

thanks for the helps......


ridvvan