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 anti-ringing circuit was found in an English documentation from 1996. The integrated circuit is...
The figure shows how to increase the gain of the amplifier stage of the previous circuit. The...
This circuit uses unusual operational amplifiers, but equivalents can be tried. FETs can also be...