Found in an 80's Electronic Design, this circuit is based on the ICL7107 which is not an easy component to obtain today. The circuit is compatible with TTL and CMOS.
This rather sophisticated circuit does not recognize false tones, such as harmonics, and can be...
Suggested by Hughes in 1968 documentation, this circuit makes use of a transistor matched pair and...
Bis This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine. The...