We found this circuit in an old Mullard (Philips) documentation. The sensor consists of a reed-switch that is coupled to a magnet on one of the wheels of the vehicle.
This circuit was obtained in a 1990 English magazine. The circuit can be assembled with equivalent power...
Varactor diodes are our varicaps of today. This circuit for switching signals in an RF circuit was found...
This basic circuit was found in RCA / GE documentation from the 90s. In it we have the way to...