In the figure we have a circuit that uses unusual components, being indicated for low frequency applications. The circuit signal is generated by a unijunction transistor that oscillates at 8 kHz.
This National Semiconductor circuit appears elsewhere on this site. The circuit must be powered by...
In this circuit the frequency is determined by the coil and the variable capacitor. Transistors like the...
This circuit is from old American documentation, but the transistor used is still very common...