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.
When the temperature rises above the value adjusted by P1 the relay triggers on. The rated voltage for the...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...
This 80's circuit uses a small light bulb as an indicator, but an LED with the appropriate resistor...