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 low drift circuit for thermocouple was found in an old European documentation. However, it is...
This complete single cell protection system is suggested by Linear Technology in its 2005 manual....
This simple circuit of low power with an LM386 includes the highly sensitive audio preamplifier...