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 flip-flop circuit with general purpose transistors was found in American documentation from...
We found this dynamic tester for transistors with variable collector current in a publication in...
We found this sensitive moisture detector in an old documentation. The circuit uses a common JFET,...