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.
The circuit is suggested by National Semiconductor in its 1994 Linear Applications Handbook. The...
Found in a 1969 Electronics World, this circuit is intended for amplifying analog cable TV...
Found in an Electronic Design from the 90s, this circuit uses a component of the time, difficult...