This low power circuit was obtained from an American 80's documentation. The circuit indicates the voltage of a battery being trimmed by the trigger point. The transistors can be the BC549.
This circuit was found in the June 1982 issue of Radio Electronics magazine. It provides reference...
With this source, it is possible to obtain a higher output voltage than that obtained by the...
This circuit was found in a 70s American documentation. The operational amplifier supports a modern...