This circuit consists of a stereo audio compressor. We found it in Radio Electronics magazine from October 1968. The circuit uses an opto-coupler made with a neon lamp and LDR.
The integrated circuit used is uncommon today. We found this configuration in Motorola's 1990...
This low power audio amplifier was found at 1992s Popular Electronics. Transistors are general...
The circuit presented uses two common transistors and is powered by the circuit being tested. The...