This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits the equivalent. It can be used and the 741 and the transistor can be the BD135. The circuit can be powered by power source.
This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits the equivalent. It can be used and the 741 and the transistor can be the BD135. The circuit can be powered by power source.
