This circuit was obtained in an old Elektor and can be adapted to use white power LEDs. The transistor must be equipped with a heat sink. The circuit has a battery charger.
This series and parallel sensor circuit was found in Popular Electronics from the 1990s. Any SCR...
This circuit is based on an MC1408, an integrated circuit that is not common today. The...
This power supply for gas laser (HeNe) was found in a 90’s Popular Electronics. It generates from 1300...