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.
The crystal in this circuit is 32.758 kHz used in TV. The circuit was obtained in an English...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This very low current circuit was found in the April 1995 issue of Electronics Now magazine. The...