Author Options:

portable phone speaker/mic Answered

ok, so I have a portable phone and would like to create some sort of hands-free speaker/mic for it. I'm not sure how to go about doing it and I'm not very internal-electronic-savvy (i.e. chipsets, soldering etc). Ideally, I would assume it should be connectible via the 2.5mm headphone jack. I have an old 2.5mm headset. It's got an ear bud and flexible arm microphone and connects via 2.5mm jack. I should also have some old computer speakers lying around somewhere. I assume that's all I should need. I would like the microphone to be part of the device and be functional, but not sure if it will pick up my voice from a far distance. I'm not too concerned about looks/style, but would be a nice addition. Functionality is my first concern right now, although I do have a few old Fossil watch containers that I could put the speaker(s) in and some sort of dock or rest for the portable phone would be nice as well. If soldering is involved, I will need very detailed instructions. Thanks again! I hope someone can help me. If someone knows of a fairly inexpensive product, I would be willing to buy (since I'm not very soldering-savvy as I said above), but I think this would be an interesting project to build.


ok i got it working. I had to solder the 2 coloured wires to + and the 2 copper wires to -. Problem is, the speaker is super low, I had to pump up the volume on my stereo to almost max just to get it to play low on the speaker. How would I go about "amplifying" the signal?

A simple audio amp: [http://www.redcircuits.com//Page38.htm Here is one using transistors]

and [http://www.redcircuits.com//Page1.htm Here's one using an Op Amp (operation amp)]

haha that is absolute gibberish to me haha. I assume I can basically solder the wire with the 2.5mm jack to an old set of pc speakers that have an amplifier, right? Either way, can you explain those diagrams that you linked to. How would I go about making one of the things in those links? Just out of curiosity.

Hmm, maybe getting one of those cheap "hearing aid boxes" that sell for $5-$14 and just using that as an amp, would do for simplicity's sake. :-)

Those things they advertise on TV for helping the hearing impaired. They are more then worthless for what they advertise them for (they pick up every movement and rustling of the clothes etc,) but they are great little pre-made GP amps.

Here is one of the more fancy ones (but they come in plain box types too for as low as $5 or so: cheap amp link

well, i took the cap off the earbud and this is how the inside of it looks. So would I simply twist attach the copper wire to the speaker's copper wire


Hmm, if the impedance is the same.....otherwise you may need to either match it, or amplify it.

this is all alien speak to me. Can you clarify what you said. What is impedence and how would I match it or amplify it??

Defining impedance then will only make is worse.

In a nutshell it is a measure of the total opposition to current flow in an alternating current circuit, made up of two components, resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance. Normally a speaker will have an approximation of the impedance in ohms written on the back.

If your output has, say 4 ohms impedance and your speaker 16, your are not likely to hear very much from the speaker or maybe some distortion.

I have a bit of the "theory" under my belt, but I am not overly experienced into the nuts n volts & hows of matching impedances.

hahaha, you're right, it made it worse :S

I somewhat understand the just of your comment and what you're trying to explain, but I don't know how to fix it. I was searching a around instructables and found this tutorial:
Ghetto DIY Pillow Speaker

...which is generally what I want to do, except add a microphone and also the jack will be a 2.5mm rather than the normal 3.5mm jack. Just as a test I tried to follow the basic steps of soldering the a normal set of earbuds (no mic) to an old pc speaker. Now unless I soldered it incorrectly, it did not work. I posted a question in the comments of that tutorial and I'm awaiting an answer from the creator of the tutorial (or anyone).

Basically, he says to "Solder the headphones wire to the speaker. Both colored wires go to the + side and both copper wires go to the - side.". But I didn't really understand that specific instruction... well read my question, it's there, just search my nickname on the page.

but if I'm (basically) using an already made speaker phone, won't that work? I have the concept/idea, I just don't know how to make it physically. The type of headset I have has an earbud with a flexible rubber microphone -- it's old but it works fine. This is my concept.. what do you think? doable?


If it is of relatively new construction, it should be ( you mention originally: I have an old 2.5mm headset.. )

well.. it's not THAT old. I just said old because it wasn't bluetooth lol. It's probably about 5 or 6 yrs old. Anyhow, I don't even know where to start.. what would the wires look like inside... would there be one wire for the earbud and one for the mic? If so would I simply solder the earbud wire to the speaker??

I am not that familiar with the construction...the last one I took apart still used a carbon mic :-)

even the least complicated set up is going to be a bit complicated. The original "speaker phones" I dealt with years ago, had the annoying habit of being "one way". On most phones, if you talk and the other person talks, you can still hear each other, but not on the old speaker phones. One at a time was the motto, so in a noisy environment, they were useless (one side would be transmitting all the time). To allow it to transmit and receive at the same time, takes a little more doing. I wouldn't even know where to start. The "one at a time" configuration (like a walkie talkie, only automatic) is fairly complex, in that one must use a few discrete ic's. The problem comes up about size too. If one is not soldering surface mount IC's then one will have a rather bulky set up.