Found in American documentation from the 1980s, this circuit uses transistors from that time. It generates increasing and decreasing tones when we press and release the push button.
This circuit was found in Electronics Handbook, Vol XIII 1993 and consists of a simple direction...
This circuit works only with carbon microphones, due its low impedance. The speaker should be good or...
This is the normal circuit of a relaxation oscillator using an unijunction transistor such as the...