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PC internal speaker

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transistor495

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What kind of speaker is this -the one found in modern motherboards instead of the old ordinary 3" types.

This one measures 15ohms and looks like a condenser mic. I think the same found in alarm clocks also. Piezo beeper?
speakerr..jpg
 
Yes it's just a simple electromagnetic sounder which is fine for the odd beep but too poor quality for music or speech.
 
No Hero, those aren't electromagnetic, it's a simple piezo element, the plastic housing is just basically a speaker enclosure, if it wasn't for the enclosure you wouldn't be able to hear anything.
I haven't seen a real electromagnetic speaker in a PC in years.
 
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Are you sure? All the ones I've seen are magnetic, I've just measured the DC resistance of one and it was out 45Ω, it's probably nearer 64Ω. This is probably because the board is designed for driving a speaker not a piezo,

I wouldn't rule out piezo for the ones which are directly mounted to the board because the driver can be specifically designed for it.

I remember there used to be a PC speaker driver for Windows 3.1 which enable very poor quality speech and music to be played if the machine didn't have a sound card. Back then 8Ω speakers were common, I hate to think how much worse it would sound on a modern machine. Not that anyone cares because all modern machines have a sound card integrated into the motherboard so there's no need for a PC speaker driver.
 
Well, curiosity doesn't end there:)..I've got a pack of about 20 of those little cute buzzers from a friend. Yesterday, I broke one of them and this is what I explored..

A rounded magnet attached to the outer case just like a small DC motor.

A coil with lots of layers of winding(48SWG I assume) placed in center, that is unmovable. >1mm gap between coil and magnet wall.

A round steel plate sticked to the coil core through magnetism. And the the half-part of the plastic case glued aligning the steelplate outer part.

15ohms DC resistance, and are magnetic. They work well at alarm tones and beep frequencies ie, around 3KHz(Resonant freq.). However as a magnetic sounding device, it produce music(bad) and reacts to dc voltages applied.

**broken link removed**
In this image look at the ring magnet through the hole(bottom view) :)
6782168942eaddedb7&.jpg

However I think piezo buzzers(pulse buzzers that responds to specific frequency only) and those with in-built drivers are also coming in the same dress..many are there in PC add-on cards.
 
No Hero, those aren't electromagnetic, it's a simple piezo element, the plastic housing is just basically a speaker enclosure, if it wasn't for the enclosure you wouldn't be able to hear anything. . . .
You sure remove the plastic housing will destroy the piezo element itself? I think I can pill it cautious apart and still make it buzz by feeding it.
 
Plastic housing plays no role in piezo buzzers except for housing. But they play important role in ceramic crystal earphones, piezo tweeters etc). My magnetic transducer's diaphram(steel plate) is actually glued to the plastic enclosure(holding).
 
They're magnetic as mentioned above.

It's true you won't destroy a piezo element by removing the case. The piezo element is just a copper disc with thin wafer of piezo crystal stuck to the back and a piece of file on the back of the crystal. The foil forms one electrode and the copper forms the other electrode. If you remove an element from its case, it'll still work but it won't be as loud because it's no longer inside a resonant chamber.
 
Hi,


I have two and they are both magnetic. I can get a wide range of tones out of them with reasonable volume, and never get that kind of range with a piezo.
 
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Hi,


I have two and they are both magnetic. I can get a wide range of tones out of them with reasonable volume, and never get that kind of range with a piezo.

Yup, they're miniature sound goodies:) we can play with deep good tones loudly at a range of around 3KHz. So I store them for future uses.
 
Well wouldn't you know it =P The only one of those I ever checked WAS a piezo. I however picked out the other bits I have and checked them.
2 are 15Ω, 4 are ~40Ω and 2 are 50Ω

I blame the one piezo one with a plastic enclosure that looks exactly the same as the magnetic ones =) I should have paid attention to the original post a little more closely too, because he said he got an ohm reading across it, and you won't on a piezo.
 
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