This circuit is from an American 80's documentation. The circuit indicates when the voltage of a 9 V battery drops below 7 V. The transistors can be BC548.
This circuit was found in the Analog Devices component manual, providing a negative voltage of 2.5 V...
This circuit, which uses only common transistors, was obtained from a 1988 publication, but can be...
This circuit is from a factory documentation (National Semiconductor) of the 80's. The power...