Using Maxim components, this circuit consists of a regulator to a boost converter. The circuit operates in the indicated voltage range. The MAX5160M consists of a digital potentiometer.
A circuit for controlling the temperature of a heating element was found in a Mullard transistor manual...
We found this circuit in a 1992 Popular Electronics. The circuit has an optical sensor with LED...
I found this circuit in an old English magazine from 1979, but it can be easily assembled with...