This circuit comes from a Gernsback Publications of the 90s. The circuit uses a general-purpose transistor as a sensor. The power supply must be symmetrical.
This simple circuit was found in the Spanish magazine “Todo Electronica”, in an edition of 1996....
The UCN4202 integrated circuit contains 4 power drivers capable of directly driving a 12 V stepper...
We find this circuit in an American publication of 1978. It is intended only for cars that have...