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.
This sensitive touch key appears on this website from other sources. This version was taken from a...
This nonlinear gain circuit was found in a 1965 Electronic Design. The configuration can be used...
CMOS 4046 (PLL) is not very common. In this circuit it generates short pulses to excite a high...