This circuit was found in the Electronics Experimenter Handbook from 1991. The sensor is a diode and the circuit has a relay according to the voltage used in the supply.
This circuit was found in Radio Electronics from the 90s. The transducer is a tweeter and the...
This circuit, obtained from a 1989 publication, can control motors up to 1.5 A. With the LM350 this...
We found this circuit in 2005 Linear Technology documentation. The integrated circuit is LT1787...