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 documentation from the 70s, this circuit uses components from that time. Some of these...
In the figure we have the way to obtain an adjustable 1 to 10 mAconstant current source. The...
This microphone circuit was found in a collection of American 80's layouts, using operational...