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.
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:
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.
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?