This PLL with operational amplifiers was found in 1969 documentation. The configuration can be adapted to use modern components. The circuit has a gain of 15 V / V and can operate with 10 kHz signals.
This circuit consists of a simple continuity test with two transistors forming a relaxation...
We found this circuit in a Popular Electronics of the 90s. The circuit uses a touch sensor formed by...
Found in National Semionductor documentation this circuit combines a tone control with an...