hey guys, has anyone used a good small speaker for their arduino projects? I am trying to find something like the ones in cell phones that are loud but small. also if the speaker could be driven directly off a headphone jack line out that would be optimal so it would not pull electricity from the arduino circuit (the arduino would be used just to switch the speaker on and off)
if anyone has any referrals that would be much appreciated
If you need small speakers, why don't you just take apart a pair headphones (I mean the type that cover all or most of your ear, ear buds probably won't have powerful enough speakers)? If you don't have an extra pair to "scarifice" buying a pair at a local store will probably be as cheap as ordering two speakers online, once you factor in shipping costs, and certainly faster.
yea that does seem faster for sure but even the over the ear headphones cannot be heard from a far. im looking for like a 10 foot distance. i really dont need high quality sound production, mainly just loudness to be used as an alarm. can piezo buzzers play music (even if its bad quality) loudly or do they only play tones?
i though the speaker phones on cell phones are the perfect example of what i am looking for but it seems hard to find something similar to those to buy simply online
Hi,
Have a look at the LM386 chips, its a really simple audio amplifier that will drive a PC Speaker very loudly, it actually makes a reasonable MP3 docking station, has only 8 pins and cost around a dollar.
Here is one example -
I use one to drive a PC Speaker in an Auduino Arduino based synth.
Duane B
well the main thing is that i want a very small speaker, something preferably smaller than a 3 volt coin cell, and it should be able to be run completely off the power of an output headphone jack (which is think would be amplified if it was coming out of a cell phone or computer right)
sdinnu:
well the main thing is that i want a very small speaker, something preferably smaller than a 3 volt coin cell, and it should be able to be run completely off the power of an output headphone jack (which is think would be amplified if it was coming out of a cell phone or computer right)
I don't think you'll get something louder than standard headphones at approximately the same size as a 3 V coin cell (at least not cheap enough for most hobbysts to afford)
How about something like this? It can do 95 dB at only ~0.3 W, and it's only about 20 mm in dia. I found it on Digikey.
wow that looks perfect in size, how do i ensure that it will work directly off the electricity from a cell phone headphone port? what would i check to see if that would work out, do i have to buy it and test it?
sdinnu:
wow that looks perfect in size, how do i ensure that it will work directly off the electricity from a cell phone headphone port? what would i check to see if that would work out, do i have to buy it and test it?
It only needs 0.3 Watts, the datasheets for audio jacks usually have ratings over 1 Watt. So just attach it to a pair of wires, add a headphone plug that mates with the jack in your cellphone and it should work.
i found a 8ohm 0.4 watt speaker thats not as small as the one you showed me (about an inch diameter) and i connected it to a male headphone jack and plugged it in and it worked! but it wasnt loud enough for an alarm, even at max volume at the source. does that mean thats the loudest the speaker will get without adding external voltage or can an amplification circuit use the same line out power and make the speaker louder without using battery power? also is it safe to just plug the speaker into the headphone jack of a cell phone? i dont want to ruin my cell phone audio port accidentally (im pretty much a noob in audio stuff)
sdinnu:
does that mean thats the loudest the speaker will get without adding external voltage or can an amplification circuit use the same line out power and make the speaker louder without using battery power?
Pretty much, with nothing else in the circuit the speaker will draw whatever current it is necessary to drive the speaker provide approximately the maximum rated wattage (or the maximum the output circuit will supply, whichever is lower) at a given voltage level. Since the only voltage drops between the speaker and jack are miniscule amount from the wire and plug, the speaker is basically at the same voltage level as the jack.
If you wanted to get louder sound from it you will have to have an amplifier of some sort. While I've never built one myself I know there are ways to do this safely, since I own a commerically made, battery powered, set of speakers with an amplifier made to work with standard headphone jacks. Of course just buying one doesn't give the same sense of accomplishment or bragging rights as making it yourself. 
is it possible to make an amplifier circuit that takes no external power? just the power received from the line in?
Hi,
That lm386 that i posted previously is a single chip amplifier, it does need power, but its an incredibly simple circuit to build, can drive pc speakers to a good volume, and has reasonable sound quality. Its a really good solution for getting more volume from a project.
Duane B
Yeap I don't think its possible to amplify the audio without pulling more volume. I really wanted to make this as passive as possible. Would an amp work off of a 3v battery?
Hi,
if you need a low power loud alarm why not try using a 3v magnetic buzzer. These are pretty loud and use very little power.
http://uk.rs-online.com/web/c/?searchTerm=buzzer&sra=oss
Cheers
sdinnu:
is it possible to make an amplifier circuit that takes no external power? just the power received from the line in?
By definition no.
MarkT has it totally right. If you had an amplifier circuit that took no external power and amplified, just make like 10^7 of them, and the power the world off of them. Or hook the input of one to the output of another, and vice versa, and create infinite energy.
Really, a basic audio amplifier can run on very low voltage (like a watch battery/cell), can be tiny if you can solder surface mount components, and do a decent job of making recognizable sound. Audiophile quality? Well, not a chance, but you could recognize words and songs, even if they sound a little funny. And forget about bass, for that you need a lot of power and a lot of speaker area to move air.
Regards,
Martin