This interesting circuit, from a digital documentation two years 1978 shows how to implement a circuit that measures the position or angle of a stepper motor controlled by a microcontroller.
MCP19124/5 Contains Independent Voltage and Current Control Loops Plus a Full Suite of...
This circuit is from an old documentation from the 70s, so the transistors used are not common....
This small transmitter can act as a wireless microphone operating in the medium wave range,...