We found this circuit in a publication by General Electric in the 1980s. The transistors and the PUT are from that time. The control is done by a tachometer based on an optical coupler.
The frequency of this oscillator depends on the crystal used. The transistors are general purpose. We...
The circuit shown in the figure serves as a pre-amplifier with a voltage gain of around 12 times,...
Found in a 1964 Philips manual, this circuit uses only passive components. The relay is a high...