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.
Found in Linear Technology documentation from the 1980s, this generator uses integrated circuits...
The operational amplifier used in this old application is not common today, but more modern...
This logarithmic gain operating configuration was found in the June 1994 Electronics Now magazine. The...