We found this circuit in American documentation from the 1980s. Transistors can be of general use. The frequency range of the generated signals ranges from 500 kHz to 10 MHz.
This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
Suggested by Radio Electronics from the 90s, this circuit is suitable for NiCAd batteries with a...
082E) We started with a simple Hartley oscillator circuit using a bipolar transistor that can...