CONTROL CIRCUIT GENERATING CONTROL SIGNAL PROPORTIONAL TO POSITION OF INPUT DEVICE

PROBLEM TO BE SOLVED: To enable conversion into a signal which is usable by a microprocessor by imposing amplitude modulation on pulses of constant frequency with a linearly increasing output signal. SOLUTION: A sensor circuit 14 is equipped with a signal conditioning circuit which performs conversion to a linearly increasing output signal Vm having its amplitude proportional to variable position input. This sensor circuit 14 is connected to a mechanical device which changes in physical position like a throttle and converts the position of the throttle to the linearly increasing output signal Vm. A pulse generating circuit 16 generates pulses Vp of constant frequency having a determined amplitude and a modulating circuit 12 is coupled with the pulse generating circuit 16 and sensor circuit 14 and generates a pulse- amplitude modulated output signal Vo representing the position of the mechanical device like the throttle. Namely, the pulse-amplitude modulation is imposed on the pulses Vp of constant frequency with the linearly increasing signal Vm and a microprocessor 24 adjust another device like the fuel/air mixer of an internal combustion engine according to the pulse-amplitude modulated signal Vo.