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.
Despite being from a 1970 General Electric documentation this circuit can be used as a shield if...
This is another quick adder that we found in an Electronic Design from the 80s. It also applies to...
This circuit was found in a 1969 Mullard documentation. Used transistors can be replaced with...