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.
This circuit delivers at its output a voltage that proportional to the amplitude of the input...
This bargraph-type circuit employs a not very common integrated circuit today, but can be adapted...
Found in a Westinghouse Silicon Power Handbook from the 60s, this circuit makes use of period...