Based on a 555, this 80's American documentation circuit detects the voltage of a battery and can then disconnect the charger. The transistor may be a general purpose type.
The critical point in this 2005 project is the adjustment of the optical system, mainly to avoid...
In this circuit of a 1968 publication the unijunction may be 2N2646 and the transistor BC548. The...
We find this circuit in documentation from the 1980s. The triac and diac are of conventional types...