Abstract: An apparatus for remotely controlling one or more power units including a transmitter which produces an optical pulse train having a frequency varied by an astable multivibrator controlled by keys which connect different resistances into the astable circuit, and one or more receivers. Each receiver receives the optical pulses, converts them to electrical pulses, divides the frequency, counts the electrical pulses, provides an analog output from the counter and compares that analog output with a saw tooth periodic waveform to control circuit elements which in turn control conduction through the power unit.

Abstract: An ultrasonic remote control device of the type having an integrated switching network formed in a multilayer printed circuit and mechanical switching means whereby at least some of the circuit connection paths intersect in a cross connection matrix with the switching means manually operable to connect each intersecting path to a common potential, for example ground.