We found this circuit in a French documentation from the 80's. The components used are still common and the circuit can generate signals from 10 Hz to 100 kHz.
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...