there's some problem

sir,i just connected the 8870 ic as u said to understand its working...

i made the connections as u said.i placed LEDs in q1,q2,q3,q4,std pins.
but problem is that all the 4 Q LEDs are glowing without even giving the input via mobile.the std LED blinks when the power is turned on and then it doesn't glow at all even when the input's given.

i accepted the dtmf input through the headphone wire by burning it and taking the 2 metal wires out, earthening one(arbiterily) and connecting the second to the the 8870 ic at 0.1microF capacitor.could there be a problem with this??

 

I think you meant to reply to this thread: http://forum.allaboutcircuits.com/showthread.php?t=35110

 

yes sir..i m new here....
can u help me with it pls,...