This simple charger was found in a 1980s documentation. The transistor may be the TIP42 with a heat sink. R1 adjusts the load current. The transformer has 1 A of secondary current.
The circuit is from a June 1995 Electronics Now. The relay is power-dependent and both R1 and R2...
This circuit for several frequencies was obtained in an American documentation from the 90s. The...
The circuit shown in the figure is suggested by AllegroMicro (www.allegromicro.com) and consists of an...