This circuit produces the sound of percussion such as blocks, drum, bell, etc. The frequency depends on the marked capacitors, which can have a wide range of values depending on the desired sound.
The simple transistor test shown in the figure can be powered by a 9V battery. The test is for...
This circuit is from an American publication from 1970. It uses a coal microphone, which is...
The maximum current of this circuit is 250 mA, its purpose being to replace 9 V batteries. Diode D1...