Found in a Popular Electronics from the 90s, this circuit is intended to measure the harmonic distortion of an audio signal. The circuit can be tuned between 970 and 1030 Hz.
Found in an EDN from the 80's, this circuit makes use of an operational one of the time. The...
This circuit is from the 80's, using an integrated of the time. The circuit serves as a reference,...
The circuit presented is from the Linear Applications Handbook of the National Semiconductor of...