This space mark demodulator for FSK signals was found in an American telecommunication documentation from the 1980s. The circuit operates with 2025 Hz and 225 Hz mark space signals.
This oscillator with the 4049 can generate signals up to about 14 MHz according to the article in the...
We found this circuit with very high input resistance in an old documentation. The circuit is still...
From an audio signal, this circuit gets two signals of the same amplitude and opposite phases....