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.
We found this basic mixer with the 741 integrated circuit in a 1992 publication. The battery is...
Suggested by General Electric in a 1968 documentation this integrated amplifier uses a component of...
Suggested by Siliconix in documentation from the 90s, this amplifier has its gain digitally...