This configuration was found in an English magazine from 1965. It is valid for any junction FET. The input impedance is 5.5 M ohm higher than conventional stages.
This circuit was found in an American 1980s documentation. Equivalent operational amplifiers can be...
This busy line indicator is very simple, serving for analog lines. The supply is made by two...
This simple circuit uses a 200 uA microammeter of the type found as VU, being able to measure...