This 4-voltage power supply using zener diodes has a maximum recommended current of 25 mA. The circuit was found in the May 1966 Radio Electronics magazine.
This source was found in Philips' 60s documentation. The transistors are from the era and the...
This circuit is the digital indicator for the previous circuit and can be used with similar...
Found in a 90s Electronic Design, this circuit operates with Maxim components of the time. The...