This circuit was found in an American documentation from the 1980s. The sensitivity ranges from 100 mV to 1 V. The supply must be done with an excellent filtering source.
This traditional circuit is from a 1972 RCA technical publication. The circuit can be developed with...
This well-known siren configuration using complementary transistors is from a 1980s documentation. The...
This 1967 Electronics World circuit is suitable for frequencies up to 1 MHz. The setting applies...