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 is from an old manual of linear integrated circuits. The LM185 is not a common...
This circuit was found in a documentation of the year 1958. The transistors are germanium types...
We find this circuit in a radio amateur publication of 1977. Its purpose is to measure the...