This detector uses an unusual sensor today. The circuit is from an 80s documentation. Its sensitivity is 10 ppm. The transformer has two secondary voltages.
This circuit was found in General Electric documentation from 1964. It makes use of a PUT, called the...
This mid-frequency amplifier circuit was found in an American publication from the 1950's. The...
The circuit with a common operational amplifier uses a zener as a reference. The circuit is from...