This circuit was found in a 1999 publication. Its purpose is to flash two LEDs according to the sound of an equipment and to randomly flash three LEDs at a controlled frequency
Found in an American documentation from 1969, this astounding circuitry makes a relay operate on 3 Hz...
The oscillator shown in the figure generates a 1 kHz tone that is reproduced on the speaker with...
General Electric suggests this circuit in an 80's documentation. The circuit makes use of PUTs...