Found in a 90s Popular Electronics, it serves both TTL and CMOS logic. The injector can provide 10 kHz or 100 Hz signals. The circuit drives a transducer and two LEDs.
This circuit is from an old documentation from 1995, but it can be easily assembled today by the...
The basic idea of this 1988 circuit is to use a signal called REMOTE existing in some types of...
Poptronics recommends this circuit for use in the car when the headlights are left on. The circuit...