This circuit with the 555, was obtained in a 90s American documentation. The signal must be applied to a good amplifier. The sound is similar to that of a police siren.
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...