This old circuit is suitable for signaling applications. The lamp must be incandescent, and the triac must be mounted on a heat sink. The frequency is adjusted in the 1 M trimpot.
This circuit generates pulses at a frequency that can be adjusted by a potentiometer. The circuit is...
This oscillator uses a small IF transformer taken from an old transistor radio. FET admits...
Found in a 1970 EEE, this circuit generates signals that depend on the C1 capacitor. Transistors are...