Found in a1967 Ferranti documentation, this circuit uses an operational amplifier from that time. The circuit uses a LDR as a sensor and has a null setting.
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...