This two-transistor circuit was found in the September 1971 issue of Radio Electronics magazine. The sensor is an NTC and sensitivity adjustment is via R1.
With this circuit it is possible to demonstrate the working principle of an optocoupler. The LEDD...
This circuit was obtained in a documentation for radio amateurs in 1974. The coil consists of 12...
This very low power circuit is based on the ICL7860. We found it in an Electronics Now from April...