I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245. The circuit works in the range of 40, 80 and 160 meters of radio amateurs.
This instrument was obtained in a documentation for radio amateurs of 1976. The circuit measures...
This circuit decodes FSK signals with frequencies of 1070 and 1270 Hz and can be used in data...
We found this circuit for guitar training in an English documentation from 1989. The components are from...