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.
Found in an English documentation, this siren of good power is indicated for several applications, based on...
The circuit used is the 4093 configured as an inverter in this application from Radio Electronics from...
This circuit is from an Italian magazine Elettronica 2000 of September 1987. It is a pulsator for...