This circuit is from a 1966 NASA documentation. The circuit uses a photodiode as a sensor. The other components are from that time.
This circuit was found in an English documentation from the 90's. Equivalent components such as...
This circuit was found in an Electronics Now of the 80s applying to NiCad batteries of the time....
The pulses applied to input C of the SAA1027 integrated circuit determine the engine speed. Each...