This 1 kHz circuit was found in American documentation from the 90s. The original operational amplifier consists of a double 741 at the time. The power supply must be symmetrical.
This circuit is an excellent shield for microcontrollers and was found in the October 1987 Radio...
We found this circuit in a 1981 publication, when it was still possible to find 22.5 V batteries (used...
This grid-dip meter was found in a 1956 documentation from Sylvania. It can be implemented with...