This circuit was found in an old American publication. The transformer is the type of output found in old transistor radios. The transducer is crystal headphone.
This circuit can be used in alarms by activating a relay or a current load that depends on the...
The circuit given below was found in the National Semiconductor Linear Applications Handbook. The...
The current of this circuit is determined by a PNP transistor. The circuit is suggested by Texas...