This circuit with junction field effect transistors was found in documentation from the 1980s. The transistors can be MPF102 or BF245 and details of the coils are not given in the original.
This circuit was discovered in an English publication in 1979. The circuit can still be assembled with...
This circuit is the digital indicator for the previous circuit and can be used with similar...
This circuit tests crystals up to a few megahertz with ease. The circuit is from a 1977...