This 1965 circuit uses a Philips 4068 tube to measure extremely small charges. The circuit has as indicator a micro ammeter and the transistors are of the time.
This stage for JFETs was found in a 1965 US publication, but is valid for modern components. |...
The circuit presented is a simple MW tuner that can be plugged into the input of any audio...
This is one of many versions of this circuit that the reader can find in this section. The circuit...