Joined Aug 6, 2010
there is alot in what you are asking, its a nice project tho.
there are a few things that you must understand about DTMF before you jump in tho. i suggest the sight How Stuff Works, the following link will tell you all about phones and the different frequencies generated by pushing keys on your telephone - http://communication.howstuffworks.com/telephone5.htm.
this next site will show you many circuits involving PIC micro-controllers and there implementation in controlling stuff over a phone network. http://www.sxlist.com/techref/member/rat_ring/index.htm


Joined Aug 6, 2010
in my own opinion and experience it is best to try and understand the back round of such a project. not knowing 1mishramudit's backround in electronics means i have to assume that this person knows very little.
As such i thought it a good idea to fill 1mishramudit in on the backround of how and why DTMF is used and then give a project.
While building the project from someone elses plans might not be too difficult, understanding what is going on and how to built, troubleshoot and maintain a project of ones own is a little bit more so. but it is still very do-able and would be a nice little project.
i suppose for me half the fun comes from the design process through constant improvements to maximise ones efforts.
sorry if thats a little off putting but its only my opinion.
electronics is to be enjoyed so have fun!!


Joined Sep 26, 2009
Thats cool with me brad, but copying someone elses circuit or not, most newbies do not get it right the first time, and that is where the learning part comes in, since they would have to know the workings of the circuit to figure out if it is working properly or not or what is not working, and how to correct it.... everyone has a way of doing things, and that is cool with me...

but on the other hand, if the op wants to "really" learn something, here is a DTMF decoder and Caller ID circuit based on a couple of Holtek Semiconductors communications IC's, but in order to get "good" use out of them it would be best to connect them to a microcontroller, this may be a little more advanced than just standard using discrete IC's.

B. Morse