stereo noise suppressor - depends on channel separation

depends on channel separation Weak VHF/FM signals, particularly stereo broadcasts, are normally received against a background of noise. When the receiver is then switched over to mono, much of the noise disappears, but so, unfor- tunately, does the stereo effect. The present circuit reduces the noise drastically, but does not eliminate the stereo effect. A potentiometer allows selection of the best compromise between noise and channel separa- tion. The circuit is simply inserted between the tuner and the amplifier. Inputs and outputs are isolated from direct voltages by coupling capacitors C1, C2, C5, and C6. The input impedance is of the order of 100 k because of resistors R3 and R4 which also provide a direct voltage to operational amplifiers IC1 and IC2. This voltage is half the supply voltage because of voltage divider R1/R2 which is decoupled by C3. The opamps function as impedance inverters with unity gain. Their out- puts are taken to a stereo poten- tiometer, the minimum v...