The main feature of this circuit found in an old American publication is that it is powered by the very signal it converts. The transistors are of the time and can be replaced by current types.
July 2017 - Microchip's new MCP39F511 demonstration and development boards, which consist of...
This circuit, which controls both the temperature and the level of a liquid in a reservoir, was...
This circuit provides a constant current of 1 mA, stabilized by an LED, which can be equivalent to that...