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 circuit is suitable for low impedance m icrophones. Gain is given by the 2M2 resistor. This...
This sensitive circuit was found in old documentation. The SCR can be any of the 106 series and...
This preamp with several inputs using germanium transistors from the time was found in Japanese...