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 traditional signal injector configuration was obtained in a 1977 amateur radio manual. The...
An integrated circuit 741 (operational amplifier is the basis of this voltage indicator, which can also...
This commercial 6-digit clock circuit was found in August 1976 Radio Electronics magazine. Note...