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.
An interesting timer is shown in the figure, using one of the 4 NAND gates of the integrated 4001....
General Electric suggests this circuit in a 1980s documentation. The operational of the time is...
This simple adjustable source uses a PNP transistor that can be the BD136 for even slightly higher...