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

DTMF Communication over 24 Volt DC Line

Status
Not open for further replies.
A

aroymkp

Newbie level 5
Newbie level 5
Joined
Nov 11, 2007
Messages
10
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,325
what are uses of dtmf communication

I need to send and receive DTMF signals over a 24 Volt DC Line. Can anybody suggest how DTMF can be modulated over DC Line. I plan to decode it using MT8870 decoder. Any help/ guideline will be highly appreciated.
 

communicate over dc

Put inductors at both ends of the line.
They should have roughly 1kΩ of imedance at the carrier frequency.
Now you can inject (via capacitors) any ac signal between these two inductors.
 

    A

    aroymkp

    Points: 2
    Helpful Answer Positive Rating
opam dtmf

Thanks a lot for your advice. Can you please put up a small schematic ? Can you please guide what specific inductor value should be used for DTMF frequencies from 0-9 . I will be much grateful for your kind guidance
 

DrWhoF said:
Put inductors at both ends of the line.
They should have roughly 1kΩ of imedance at the carrier frequency.
Now you can inject (via capacitors) any ac signal between these two inductors.
Click to expand...

Can you give any idea about the value of inductor to be used.
 

I think you need inductors of at least 100mH.
 

    A

    aroymkp

    Points: 2
    Helpful Answer Positive Rating
do i need to put an op amp for receiving end?
 

I don't think so. Most of DTMF receivers have op-amp at the input stage and it's gain can be adjusted with two external resistors, same as in an independent op-amp.
:D
 

    A

    aroymkp

    Points: 2
    Helpful Answer Positive Rating
dtmf is generated using uC - is it sufficient or it should be amplified?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top