Piezo Buzzers

Smaller than *what*? A breadbox? And how LOUD is LOUD to you? 85dbA at

Best regards, Spehro Pefhany

Piezos are the acoustic scourge of the electronics age. Nasty little things. It's not hard - fun, actually - to make bell, gong, wind-chime, bird-chirp, explosion, or other more interesting sounds with a speaker.

John

Big hamfest there, no?

Best regards, Spehro Pefhany

If you have a low voltage source you can still get a fair bit of bang by driving a dual RS232 out of phase and using the outputs to drive a piezo.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

Which Wal-Mart is the best one to go to in Dayton?

If you want a Piezo in Dayton you go to Mendelson's :)

I do. They are small an loud.

I hope this helps.

For deaf people like me, the frequency of piezos is usually much too high. We need something below 1 kHz to be able to hear it clearly.

Small, as perhaps to fit in a handheld enclosure. Perhaps big around as a quarter, a half inch tall.

Loud as in as loud as they get. Real screamers. I find alot in that 85-90dB range to be way too quiet.

I haven't been to the dayton hamfest since 1987. :(

General Admission Ticket: Don't get stuck in line, get your advanced 2005 Hamvention tickets for the May 20, 21, 22, 2005 now. Admission tickets will be $25.00 at the show.

I read in sci.electronics.design that Brian wrote (in ) about 'Piezo Buzzers', on Fri,

How old are you? Maybe you don't hear so well any more. If so, try to find a product with a lower frequency (between 1 and 2 kHz), which is likely to be more costly because they are made in much smaller quantities).

Have you measured 85-90 dB? These things use a resonant cavity (Helmholtz resonator) to boost output a lot. If the piezo is even a bit off-tune with the cavity resonance the output drops considerably.

Not possible with the self-oscillating electrode tapped piezo ceramic disc types....and anything that could be called an alarm is more like

It is really an issue of impedance matching, isn't it. The little chamber works like a stripline matching network between the high impedance of the piezo device and the lower impedance of the air.

Attaching the piezo element to the case and providing a port through the case can ve very loud.

Motorola used to make 4 inch piezo tweeters. These work even better. Even someone with hearing protectors thinks its too loud.

I read in sci.electronics.design that Ken Smith wrote (in ) about 'Piezo Buzzers', on Sat, 19 Feb 2005:

Yes, we could get around 105 dB SPL at 1 metre anechoic. But they were not very reliable; in general, not just in that application. And the linearity was conspicuous by its minuteness. (;-)

They did work great to make the "woooo-weeee" sort of noise that people expect from a metal detector though. It is best to drive them through an inductor and use a square wave. The inductor keeps the current spike on the edge to mere amps and actually seemed to make more of the power end up in the audio range.

One day, one of the bosses was in the lab. He said "I'm sure glad you turned that off". I had to inform him that no, it was screeming away at about 7 or 8KHz. Wearing hearing protection ear-muffs while using an oscilloscope ... oh the memories.

Here, I found one, it's LOUD (138dBA @ 100') and could be considered relatively compact for the sound level:

Best regards, Spehro Pefhany