This circuit was found in a Philips documentation from 19678. The transistors are from the period with emphasis on the married pair. Modern equivalents can be used.
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...