This circuit was found in 1980s American documentation. The transducer is a piezoelectric capsule and the power supply voltage can be between 3 and 18 V.
The transistors of this circuit can be BC548 for NPN and BD136 for PNP with load up to 500 mA. The...
This circuit is suggested by National Semiconductor and is based on a double operational amplifier of...
This mid-waveband receiver was found in a book on transistors from 1954. The antenna coil is of...