We found this circuit in a 1965 Electronic Design. Transistors are still common but admit equivalents for some of them. The circuit drains a current of only 4 mA.
This 6-transistor commercial radio with 6 V supply was found in a Japanese publication from the...
This circuit is suitable for automotive signaling applications. The integrated circuit is not...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...