Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to interface DTMF receiver & phone line w/o transfor

Status
Not open for further replies.
F

Free_Will

Member level 3
Joined
Apr 6, 2002
Messages
65
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Activity points
581
capturing DTMF codes

I want to record the dialed numbers from a phone line to a microcontroller.I know about DTMF receiver IC and microcontrollers.My problem is what is the interface between the DTMF receiver IC and the phone line(not phone) without using any transformer.

Can you please advise me?

Thanks
 

Hi

Have a look at **broken link removed**

They provide DAA for voice and data without transformer, but with optical isolation... See LITELINK III
 

I'll be glad if any other advise rather than offering particular IC.
 

Using a differential opamp circuit(Set an input impedance to be more than 200Kohms) and tap it directly to the line(After the relay). This should do the job. I use to do a telephone recorder this way. This is just an idea. I'm not sure wheter it will cause any other problem. But I've done this and it seem to work ok for my application.

:p
 

This is what I use

This is what I use
 
  • Like
Reactions: brm

    B

    brm

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top