Signal control circuit

Claim 1

A transistorized signal control circuit for controlling the amplitude of a signal without changing its DC voltage level, comprising a pair of transistors of substantially equal characteristics and each having first, second and third electrodes, means connecting said first and second electrodes of each of said transistors across a DC voltage source in the same conductive direction, means for receiving the input signal to be controlled and supplying said input signal to said third electrode of each of said transistors with the phase of said input signal thus supplied to one of said transistors being opposite to the phase of said input signal supplied to the other of said transistors, a plurality of series-connected resistive elements connected between said second electrodes of said pair of transistors and including an inteRmediate variable resistive element, and a pair of output terminals connected with said series-connected resistive elements at opposite sides of said variable resistive element, switching means connected between ground and the connection of each of said output terminals with said series-connected resistive elements, and control means controlling said switching means for selectively causing shortcircuiting of said output terminals.