The TBA120S is a monolithic integrated circuit specifically designed for audio detection in TV and FM radio receivers. It incorporates an 8-stage limiting I.F. amplifier and balanced detector plus a DC-operated volume control. The TBA120S is supplied in four groups depending on the resistance required between pin 5 and the ground to attenuate the audio output by 30 dB. Pins 3 and 4 are connected to the collector and base of a transistor which may be used as an AF-preamplifier or as a switch.
