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 takes advantage of the noise generated at the junction of a zener diode of any type....
This low-frequency oscillator was found in a 1963 documentation. Capacitors determine frequency. The...
This configuration with FET and Unijunction can be found elsewhere on this site. The JFET admits...