This TTL circuit is from a Radio Electronics magazine from February 1973. The circuit must be powered with 5 V and the maximum frequency depends on the TTL integrated circuit.
This circuit was obtained from an English magazine from 1977. The magazine no longer exists, but...
Using integrated circuits from the time, we found this audio compressor in an English publication from...
This circuit was found in a Poptronics of the 90's. The FET is double-gate, and the frequency...