Playing music through the phone

[Elkaid]

Hi,

I need to build a device for my uncle (musician) that allows him to play music (from cd player, tapes etc.) through the phone so his customers can have a quick idea about the work being made.

I know emails or internet would be easier but he can't use it.

Anyone with ideas ? schematics ?

Thank you very much.

 

[soongsc]

No computers? Just interfacing the device to the phone lines? It might be possible using a computer with a modem.

 

[Elkaid]

I think I expressed myself incorrectly

I simply want to use a cd player's output and connect it in parallel to the telephone's microphone so the listener can hear the music through his phone.

Could it be easy as that ?

Thank you

 

[pinkmouse]

I don't know what it's like over there, but in the UK it's illegal to connect an unapproved device to the phone line.

 

[soongsc]

If you like DIY, this site might be usefull.
http://www.tkk.fi/Misc/Electronics/circuits/teleinterface.html

Otherwise, there are also other commercial devices that give you line inputs to the phone line.

 

[macboy]

Keep in mind the inherent limitations of the phone system, namely the bandwidth, which goes from about 300 Hz to 3500 Hz (the sampling rate is 8 kHz).

 

[soongsc]

It also has DC on it along with ring high voltages. That's why you need the proper decoupling.

 

[Elkaid]

Thank you,

Keep in mind the inherent limitations of the phone system, namely the bandwidth, which goes from about 300 Hz to 3500 Hz (the sampling rate is 8 kHz).

Thanks. In my case, quality isn't an issue. The goal is to give the customer a "preview" of the project progress so he can give his impressions in real-time.

I don't know what it's like over there, but in the UK it's illegal to connect an unapproved device to the phone line.

Uhhhh... I'm not sure here in Canada but I suppose it's "legal". Maybe that could explain why phone companies are selling "line" insurances in case something blow up between your phone and the telco.
As some says : you're allowed to do anything as long as you don't get caught. Anyway, your point deserves investigation. Thank you.

 

[Bill Fitzpatrick]

What you are looking for is a telephone audio coupler.

Here's one. Google for others.

http://www.testequipmentdepot.com/skutch/tacoupler/t21p.htm

Check with them to make sure it's usable in Canada.

 

[Elkaid]

Thanks !

I found the following schematic and it would be nice if you could give me your comments about it.

http://home.maine.rr.com/randylinscott/jul98.htm

If I want to be able to speak at the same time as the music plays, can I simply remove R1 ?

Thank you

 

[dnsey]

What advantage do you hope to gain over placing the phone mic near the music speaker?
Sometimes the simple option is the best!

 

[Elkaid]

uhhhhh ?

Well, that's a pretty good question. Since my uncle lives in an appartment, maybe he doesn't want to disturb neighbors ?

 

[soongsc]

Thanks !

I found the following schematic and it would be nice if you could give me your comments about it.

http://home.maine.rr.com/randylinscott/jul98.htm

If I want to be able to speak at the same time as the music plays, can I simply remove R1 ?

Thank you

The circuit looks goo. You might want to see if the CD player has an earphone jack and volume control or not. Normal RCA outputs don't handle 600 ohm impedance well, and you might want to adjust vlume.

If you plug this circuit along with the phone, you would be able to talk while you play when the switch is on.

 

[Elkaid]

Unfortunately, there's no volume control. Is 600ohms too low for RCA outputs ? Could a simple potentiometer between the cd output and the coupling tranformer correct the problem ?

Thank you very much !

 

[soongsc]

Most CD outputs like at least 10K. If the CD player has a remote controlled volume, you might just at a buffer. I'm not really sure whether a potentiometer will work or not because I normally don't deal with tranformers in the signal path.

Normally the CD manual would specify what kind of load the RCA output interface requirements are.

 

[Elkaid]

Thank you very much

As suggested, I'll simply add a buffer circuit

Have a nice day !