I implemented this circuit and it works fine but now that i have to demonstrate it soon i don't know why each part was choosen as the values seen in the circuit.
From reading the MT8870 DTMF decoder datasheet i know its the differential input configuration used and that gain setting can be used...Why does it need a gain and how dto calculate these values shown?
I implemented this circuit and it works fine but now that i have to demonstrate it soon i don't know why each part was choosen as the values seen in the circuit.
From reading the MT8870 DTMF decoder datasheet i know its the differential input configuration used and that gain setting can be used...Why does it need a gain and how dto calculate these values shown?
Sorry for responding so late...Here is the code...Should tell you how to get the duration of calls but its an estimate...I created functions to count secs, mins, and hour. To get the actual exact duration you would need to determine when the person lifted the receiver on the other end. In some networks, this is detected by a polarity reversal of TIP and RING...You could use my timing if you require just an estimate and not the exact timing.