This circuit from Popular Electronics powers a small speaker. The transistor can be of general use and the capacitors can be altered to change the sound generated.
This circuit was found in an English operational documentation from 1970. The circuit can be...
This circuit is from a 1974 publication. It generates a pulse with several sinusoidal cycles from...
This solar cell driven circuit makes 4 LEDs run at a speed given by capacitor C2. The circuit is...