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I am designing a fairly simple board where I need to sound a simple chirp/beep every couple of minutes, however, layout space is extremely limited.

Therefore, a full-blown piezo buzzer is a no-go; they mostly seem to be of at least 10 mm diameter based on my research.

I am interested in a type of part or circuit within less than 6 mm X 6 mm X 3 mm of board space, which can produce a chirp/beep (of around 10 to 20 dB, i.e., audible from about 5 feet away). Is this achievable?

For instance, I recall encountering a high-pitched noise in the past from an inductor within a buck-boost regulator circuit -- the sound wasn't loud enough but I am also curious to see if there are methods to reproduce something similar but with greater amplitude.

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  • \$\begingroup\$ 10 to 20dB - is that sound pressure level you refer to? \$\endgroup\$ – Andy aka Oct 21 '13 at 13:17
  • \$\begingroup\$ microbuzzer.com/smd-electro-magnetic-buzzer 5 x 5 x 2.5 mm ? docs-europe.electrocomponents.com/webdocs/1200/… ? \$\endgroup\$ – RedGrittyBrick Oct 21 '13 at 13:18
  • \$\begingroup\$ Earbud speakers? \$\endgroup\$ – Andy aka Oct 21 '13 at 13:24
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    \$\begingroup\$ Not an exact duplicate, but a question on this site asking for a buzzer with nearly the same dimensions: Small Piezo Buzzers. Also, a parts search shows up several SMD buzzers, piezo or electromagnetic, in the 5050 package, i.e. 5 mm x 5 mm x 2.5 to 3 mm, with sound intensity at 10 cm rated up to 78 db, perhaps more. \$\endgroup\$ – Anindo Ghosh Oct 21 '13 at 13:30
  • \$\begingroup\$ @AnindoGhosh: Where are you searching? E.g., when I tried on Digikey, in the buzzer category, the minimum dimension was 10 diameter. \$\endgroup\$ – boardbite Oct 21 '13 at 13:52
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At first, trying to use some side effect, as the sounding inductor core, you will end with very low efficiency.

RedGrittyBrick already pointed you to some existing buzzers as small as you need. Here is another proof link, that demonstrates that such buzzers exists.

If you really want to try something in DIY manner and is dexterous enough to work with 5x5mm electromechanical devices by hand, you can try to design some small electromagnetic speaker from a small solenoid and some thin iron foil as a membrane. Optional an anchor with a small hammer at the end that to knock on the internal side of the enclosure.

Another option is to open the smallest accessible piezo-buzzer and to try to cut only one part of it.

But all this is a very fine work and not everyone can do it. And is it worths?

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  • \$\begingroup\$ Got it. For the inductor-based approach: I thought about the cost and size but never considered the efficiency indeed! (And I am trying to do this for a volume design, so the DIY approach isn't suitable, but thank you for the hint.) \$\endgroup\$ – boardbite Oct 21 '13 at 13:57

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