This circuit was found in the April 1971 Radio Electronics magazine. It uses common transistors and can be adapted to use an LED or audible indicator instead of a light bulb.
This circuit generates sinusoidal and cosine signals of 2 kHz given basically by the values of C1...
This circuit was found in a Dutch documentation from 1970. The circuit makes use of semiconductors that...
This circuit has both frequency and duty cycle control. We found it in the October 1992 Radio...