This small signal amplifier circuit was found in Motorola's 1969 documentation. The FET and the transistor can be of any type and is battery powered since the consumption is very low.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit is from a Radio Electronics from the 90's. The integrated circuit is from the time...
This circuit is from an old documentation, making use of an operational of the time. The circuit...