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.
July 2016 - It can be obtained from Mouser Electronics new trinkets Adafruit. These trinkets are...
This circuit allows you to read resistors up to 20 M ohms, converting it into voltage. The circuit is...
In fact, this is the circuit also known as “vox”, that is, a relay triggered by sound. This...