:)thx audioguru :) ,ya it is confusing ??? but i really want to make this circuit i need some help from u guyz 1- i found the 74hc series in my country ,is it ok to us them . 2- what is the range of this device . 3- i cant find the 200mhz crystall so i will try to use the frequency multipier with 50mhz. thx for ur help