Electronic Fader for Broadcast Studios

An electronic fader that is capable of effecting bidirectional control of program level without any mechanical effort, like rotation of the control arm of a conventional fader, is described. This fader consists of a system of flip-flops and logic circuits which, in conjunction with dual-transmission gates, switch various steps of a ladder-type attenuator to increase or decrease the program level in the output line when clock pulses are fed, respectively, to the "forward" or "reverse" bus-bars of the system. To achieve smooth variation of level during any change of attenuation, a "make-before-break" type of switching has been ensured by the use of pulse-stretcher circuits.