Switch-on noise suppression - is performed in television integrated audio stage circuit using damping circuit with zener diode

摘要

The audio circuit consists of a single integrated chip (15) to which a potentiometer (13) volme control (14) signal is fed, and from which a loudspeaker (47) is driven through a capacitance (16). A feedback loop (through another capacitance (18) is also incorporated. The 25 volt supply to the circuit is applied through a filter or smoothing network containing an external capacitance (20) and another capacitance (22) resistance (21) smoothing network. The effect of this is to produce a slow initial voltage increase after switch-on, followed by a sharp impulse (28) when the certain circuit thresholds are crossed. By including a zener diode (25) and a further resistance in the smoothing network, a smooth and noise free voltage growth (29) can be guaranteed.