Found in Motorola documentation from the 1970s, the circuit presented uses a component from the era that is not common today. The characteristics of the coils are given next to the diagram.
This circuit is from an application manual for linear instruments from Texas Instruments. The...
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
The presented circuit uses a window comparator to keep a relay activated only when the sensor is...