This commercial earphone receiver was manufactured in the 1960s in Japan. It was powered by a 9 V battery and the transistors were made of germanium.
We found this circuit in an American publication from the 1990s. The triac must be equipped with a heat...
This TTL circuit uses LED indicators and must be powered by a voltage of 5 V. The capacitor...
This circuit uses an integrated CMOS having the frequency determined by the resistors and...