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.
This ultra-simple circuit has the frequency determined by the LC network. Any general purpose JFET...
Found in American documentation from the 1990s, this circuit uses coils with multiple outlets to...
I found this circuit in a 1986 English magazine. It can still be easily assembled, exchanging Q1...