The smallest piezo

[DigiTan]

I'm working on a portable security device and one of the key components is a 70dB piezo buzzer closely resembling this one at Radio Shack.

The problem is this machine I'm building is fairly small--amount the size of a hockey puck and I'm already low on component space. I was hoping I could find one of those very small peizo buzzers they use in digital watches, but nothing's turned up yet online or in the shops. Before I try smashing my stopwatch open, I wanted to see if any of you guys know an place that sells mini buzzers. I'm having trouble narrowing down my digikey searches. I'm not picky about loudness or anything like that, but it should operate at 12 Volts or less.

 

[audioguru]

I've been looking for the same thing. I have one similar to the RadioShack one, but at only 3V (a small lithium coin battery) it isn't loud enough, and its fairly large case is its acoustic resonator.

I have some broken cell phones and wondered how they can possibly ring and play music so loudly. I took one apart and found its tiny speaker. It is 1/2" diameter and is 32 ohms. It looks exactly like an in-ear headphone only its case is thin metal instead of thick plastic. So I played tones and music through it and could hardly hear it unless it was against my ear. Then I placed it against a thimble (the sewing kind) and swept the frequencies and it was extremely loud at the resonant frequency of the air in the thimble!

I will mount it in a small sealed case and tune its oscillator's frequency to the resonant frequency of the case. It isn't a high impedance piezo so will need a small bridged power amp IC like an 8-pin MC34119 to drive it and the 3V coin battery should make it beep for quite a long time.

Try an in-ear headphone as a speaker and tune its frequency to resonance. With your higher voltage then a little LM386 power amp IC could drive it well. :lol:

 

[chemelec]

I have about 30, Very Thin, 1/32 inch thick resonators, but they are 1.4 inch OD. Best Frequency is between about 1.5 and 4 KHZ.

If you think this may be suitable and if Either or both of you want one, Email me and I'll mail you each one for free.

Ideally: Making a Small cavity will tune them for a much Louder sound.

Take care.........Gary

 

[audioguru]

I have about 30, Very Thin, 1/32 inch thick resonators, but they are 1.4 inch OD. Best Frequency is between about 1.5 and 4 KHZ.

Thanks Gary but no thanks. I have one that I removed from my son's alarm clock and replaced with a much better 1" speaker and MC34119 bridged power amplifier IC. The piezo one is crap.

 

[Oznog]

Those "personal alarms" take a 9v battery and scream like there's no tomorrow. Those are like 120db though, you'd want to decrease the amplitude.

 

[Mut]

You might find something in the alarm or piezo sections of The Electronic Goldmine website.

 

[DigiTan]

Sounds like I need to check out those personal safetly alarms too because the 120db piezo it's also using is really big. So big, I had to mount it externally. Is there a specific name for these mini-peizos?

 

[audioguru]

I would name a mini-piezo a "beeper".
Don't get one that is too small or its high frequency will be heard only by dogs and bats.

 

[zevon8]

Not sure if you looked there already, but Digi-Key has some very small speakers and piezo transducers:

Piezo: **broken link removed**

Speakers and card speakers : **broken link removed**