This circuit that emits siren sound can be used in a fire alarm. We found it in an old American documentation. The signal must be applied to a good audio amplifier.
This circuit was found in a Mullard transistor manual from 1960. Note the symmetrical power...
This amplifier step with a transistor has an input impedance of 100k to 10 M. The transistor can be any...
I found this little signaling transmitter in old American documentation. The circuit has a good...