This is a design circuit for decoder circuit that can be use for DTMF circuit for PC. This is the figure of the circuit;
Our DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Window's program can be placed in the minimize mode and still detect tones while you use your computer to do other things like We are now in the process of adding an DTMF decoder which will interface to the sound card game port.
