Used in radio reception, this circuit was found in the February 1983 Radio Electronics magazine. The integrated circuit is the NE570 IC, and the power supply is 3.6 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...