Hi,
I am looking to play a song via a landline phone. The phone would not be hooked up to phone service, it would just be a music player, like headphones - but instead of putting on headphones you'd pick up the receiver and you would hear a song. Maybe you'd have to press a button first. Anyway, does anyone know if / how this could be done? I am not experienced with electronics, but I want to do this for a gallery show that includes a music element, and am hoping someone could point me in the right direction.
thank you!!!

 

Yes, probably. From what phone system did the phone come from?

 

Yes, probably. From what phone system did the phone come from?

ooh, I have a couple options. what do you mean by what phone system? I have a couple old rotary dial phones, and would also probably want to use some touchtone corded phones. (ideally I'd get a different song on 6 different phones).

 

If they are similar to the phones installed in homes and offices in the U.S. I can give you an idea. If they are specially designed for a private phone system or not the same type used in the U.S. I don't know whether these comments apply.

For the U.S. style phones made by Western Electric all you need is two wires. Connect the two wires (yes, your phone might have more, but try different combinations until you find the "talking pair"). Connect those two wires to the output of your audio amplifier and you are good to go.

 

If they are similar to the phones installed in homes and offices in the U.S. I can give you an idea. If they are specially designed for a private phone system or not the same type used in the U.S. I don't know whether these comments apply.

For the U.S. style phones made by Western Electric all you need is two wires. Connect the two wires (yes, your phone might have more, but try different combinations until you find the "talking pair"). Connect those two wires to the output of your audio amplifier and you are good to go.

Ok, copy western electric phones , thank you. For connecting , I could use speaker wire ? And so, sounds like the easiest way to do this is to input the music to an amplifier or something that has a speaker wire input? It’s currently ... mp3s so need to figure out the series of devices it will need to run through.

Also - would I connect the receiver directly to the audio output or could it run through the phone base and then to the receiver ?

 

You can probably get by running the audio through the telephone cable. If you need it to be louder just find the pair from the headset, disconnect it from the sidetone coil and drive it directly.

Yes, speaker wire should be fine.

 

Ok, copy western electric phones , thank you. For connecting , I could use speaker wire ? And so, sounds like the easiest way to do this is to input the music to an amplifier or something that has a speaker wire input? It’s currently ... mp3s so need to figure out the series of devices it will need to run through.

Also - would I connect the receiver directly to the audio output or could it run through the phone base and then to the receiver ?

If this is for some sort of experience thingy, you might want to consider providing "talk power" so the phone's "sidetone" works. That's the feature that allows you to hear some of the mic (your own voice, ambient sound) in the receiver. It makes it like a phone call instead of just a dead handset.

To do it, you will have to provide about 9V DC to the phone, and couple your audio capacitively to block the DC from your amp.

Depends on the goal here.

 

Hi,
I am looking to play a song via a landline phone. The phone would not be hooked up to phone service, it would just be a music player, like headphones - but instead of putting on headphones you'd pick up the receiver and you would hear a song. Maybe you'd have to press a button first. Anyway, does anyone know if / how this could be done? I am not experienced with electronics, but I want to do this for a gallery show that includes a music element, and am hoping someone could point me in the right direction.
thank you!!!

Just as a matter of interest, Thaddeus Cahill already did this in 1906:
https://en.wikipedia.org/wiki/Telharmonium

 

The receiver of an old telephone has a narrow frequency response with some awful peaks and high distortion that are a horrible way to hear music.
Also, it ain't in stereo.

 

The receiver of an old telephone has a narrow frequency response with some awful peaks and high distortion that are a horrible way to hear music.
Also, it ain't in stereo.

If you replace the receiver insert in the handset with an earpiece from modern headphones you will get really good audio.

 

Hi,
I am looking to play a song via a landline phone. The phone would not be hooked up to phone service, it would just be a music player, like headphones - but instead of putting on headphones you'd pick up the receiver and you would hear a song. Maybe you'd have to press a button first. Anyway, does anyone know if / how this could be done? I am not experienced with electronics, but I want to do this for a gallery show that includes a music element, and am hoping someone could point me in the right direction.
thank you!!!

An important question- Are the two phones in the same location, or is one phone at one house, and one phone at another house? I'm asking this question simply to ensure we all understand what you're trying to achieve because each outcome has a broadly different solution.

 

Take a look at this.
https://www.rane.com/note150.html

Your voltage source does not need to be 48volts, but what ever you use should 'drop' about 6 volts across ring and tip coming into the phone and have a 600 ohms source impedance in order to 'do' audio.

In the US, Ring is (or should I say was) red and Tip is (was) green. Typically the other two wires were Yellow and Black and were used if you had a 2nd line.

Ring was referenced to ground and tip was referenced to -48 volts. Limiting resistors at the voltage source are equal and should result in the DC voltage across ring and tip at the phone jack being in the "middle" and measuring about 6 volts. A 48 volt voltage source would drop 21 volts from the central station, 6volts across the phone and 21 volts from the phone back at the CO. The internal DC resistance of the phone is 180 ohms. Ohm's law should be your guide in figuring out the limiting resistors.

The idea was to keep the signal 'longitudinally' balanced. Using a positive ground helped reduce corrosion. In your application, this is probably not necessary and you will have a wide choice of voltages as long as you let the phone have 6 volts and make the source look like 600 ohms to the phone.

In order to develop audio back at the voltage source point, you should make the source equal to 600 ohms. Another 1:1 600 ohm audio transformer with one tap in series with each of the battery feed voltage sources may be necessary.

Also as the DTMF frequencies are harmonically related to each other, quite a lot of songs may be produced by the key pad.

The impedance of the network is 600 ohms and is why the 1:1 600 ohm transformer in the above link is used.

The audio signal levels are (were) typically between -12 < dbm <- 10. Where 0 dbm is 0.775 Vrms across a 600 ohm load. This is also equal to 1 milliwatt.

 

An important question- Are the two phones in the same location, or is one phone at one house, and one phone at another house? I'm asking this question simply to ensure we all understand what you're trying to achieve because each outcome has a broadly different solution.

the phones are all at the same location!

 

thank you for the information so far! I want to clarify something -
the music is currently in mp3 format. what are your thoughts on the best way to get it into a format for transmitting to phone? ie a speaker wire format? I'm wondering if there is any affordable way to do this for a couple of phones.

 

Hello:

Here is an interface circuit that should work. I dragged a phone out of my junk drawer and did the following.
Turned out that I only needed 2 resistors and 2 caps. No transformer.

Connected a variable power supply up to the Ring (Red) and the Tip (Green wires. With positive on Ring and Negative on Tip, I adjusted the voltage to 6 VDC. Measuring the current, I got 20mA. Using Mr Ohms law I concluded the DC resistance of the phone was 300 ohms.

You should use a 12 Volt (or greater) power source. In order to limit the voltage across Ring and Tip, you should place a 180 ohm resistor in series with the power source to Tip and another 180 resistor to Ring if using 12VDC. If you elect to use a higher voltage, you need to apply Mr Ohms law to figure out the value of the 2 battery feed resistors.

You should now be able to hear the DTMF signals in the phone as you press the keys.

The purpose of the 180 ohm resistors are 2 fold.

1. Limit the current thru to phone to 20mA.
2. Develop a signal. Without them any signals would be shorted out by the power supply.

The purpose of the capacitors is to block the DC current from getting into your MP3 Player.

Also notice the signal source is balanced between the + and - supply. This would be handy if you were to use the signal for further processing and it also tends to minimize common mode noise on the line.

In order to produce audio, you need to feed the audio thru 2 capacitors as shown in Phone_Audio.pdf attached.

I applied an 0.775 Vrms 1KHz signal and the sound in the ear phone was very loud.

A 0.075 Vrms 1 Kz tone was quite easy to hear.

The frequency response on these old phones is quite limited. Not much above 3KHZ and not much below 300 HZ.

Injecting mp3 audio at the caps, per the attached, should result in a good response.

Sounds like a fun project. You could use the DTMF signals for other control functions. (There is a chip for that)

 

Hello:

Here is an interface circuit that should work. I dragged a phone out of my junk drawer and did the following.
Turned out that I only needed 2 resistors and 2 caps. No transformer.

Connected a variable power supply up to the Ring (Red) and the Tip (Green wires. With positive on Ring and Negative on Tip, I adjusted the voltage to 6 VDC. Measuring the current, I got 20mA. Using Mr Ohms law I concluded the DC resistance of the phone was 300 ohms.

You should use a 12 Volt (or greater) power source. In order to limit the voltage across Ring and Tip, you should place a 180 ohm resistor in series with the power source to Tip and another 180 resistor to Ring if using 12VDC. If you elect to use a higher voltage, you need to apply Mr Ohms law to figure out the value of the 2 battery feed resistors.

You should now be able to hear the DTMF signals in the phone as you press the keys.

The purpose of the 180 ohm resistors are 2 fold.

1. Limit the current thru to phone to 20mA.
2. Develop a signal. Without them any signals would be shorted out by the power supply.

The purpose of the capacitors is to block the DC current from getting into your MP3 Player.

Also notice the signal source is balanced between the + and - supply. This would be handy if you were to use the signal for further processing and it also tends to minimize common mode noise on the line.

In order to produce audio, you need to feed the audio thru 2 capacitors as shown in Phone_Audio.pdf attached.

I applied an 0.775 Vrms 1KHz signal and the sound in the ear phone was very loud.

A 0.075 Vrms 1 Kz tone was quite easy to hear.

The frequency response on these old phones is quite limited. Not much above 3KHZ and not much below 300 HZ.

Injecting mp3 audio at the caps, per the attached, should result in a good response.

Sounds like a fun project. You could use the DTMF signals for other control functions. (There is a chip for that)

Hi, thanks for the thorough response !! I will give this a try.

 

One little edit.

The resistor values should be 150 ohms, not 180 ohms. (150*0.020 A = 3.0v).

Also if you have any trouble using or obtaining the older phone connectors, a CAT5 RG45 connector will work on the phone plugs as well.

Pins 4 (Tip) and 5 (Ring) (blue and blue/white).

 

One little edit.

The resistor values should be 150 ohms, not 180 ohms. (150*0.020 A = 3.0v).

Also if you have any trouble using or obtaining the older phone connectors, a CAT5 RG45 connector will work on the phone plugs as well.

Pins 4 (Tip) and 5 (Ring) (blue and blue/white).

One question - this is connecting to the phone base cable or the receiver to base cable?

 

You need an MP3 player board, search for that on EBay, and ask us with a link to confirm that it will work. Look for one with audio amp integrated to save $ and complexity.

Bob

 

dont think much is required for an old phone.

Something to play MP3 songs is first on the agenda.

I'd see what can b e done to use the switch hook to initate play.

The fidility will be very poor. the frequency response is only up to 3500 Hz. replacing the earpiece would be in order.

not saying it can't be done, but:

Voice recognition to play songs.

Hook up to Google's Alexa.

Touch-tone will be considerably harder.

Here https://www.midians.com/specs/dtmf-encoders-decoders/ttd-5 is a place to start with to use the keypad to select one of 16 songs. It depends on the MP3 player how easy it might work.