Found in a 1967 documentation this circuit can be applied to any operational amplifier. Components without values determine the frequency to which the circuit is tuned.
The oscillation of the relay causes the applied audio signal to deform and start to resemble the...
We found this amplifier in a publication of 1990, but it can be mounted today with some exchanged...
We found this project in an old publication from 1983. The circuit uses 4 switches of 1 pole x 8...