Found in na 1970 EDN this circuit has a parallel regulation providing a symmetrical output of 15 V. The transistors are from that time.
Found on Popular Electronics this circuit has variations found throughout this site and section....
This charger sources currents in three ranges: 10 mA, 25 mA and 50 mA; Current is sellected...
This circuit, obtained from ancient English documentation, produces a pulse every 24 hours when a 50...