This circuit is from a Radio Electronics from July 1965. The circuit uses components from the time also controlling a servo from the time. The power supply is 28 V.
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...