This circuit, which controls both the temperature and the level of a liquid in a reservoir, was found in an Electronic Design from the 90s. The circuit is based on a double 555.
This small earphone amplifier with germanium transistors was obtained in a Japanese publication from...
The sensor for this circuit is a phototransistor. We found it in the April 1971 issue of Radio...
Found in a 90s Popular Electronics, this circuit allows to select the operating ranges between...