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 is one of the many hysteresis comparator circuits the reader may find in this section and on this...
In the figure we have an application of an oscillator 4013 as voltage multiplier. It consists of a...
This circuit was found in a 1978 British magazine, but it can still be mounted by simply replacing the...