I am trying to find a small piezo transducer for my project and I am having trouble finding anything that matches my requirements. Here is what I am looking for:
Frequency Range: 1 kHz to 30 kHz or so Loudness: 50-60 dB Voltage/Current/Power: 5V, 20 mA, ~100 mW (suitable to be driven directly off Arduino digital output)
These requirements are somewhat flexible, so I'll briefly describe what I am trying to make. This is for a robotic cat toy, and I want it to be able to beep and squeak. I would like to make some sounds that are audible to humans, but I would also like to be able to make some tones that are outside human hearing (nominally 20 Hz to 20 kHz), but audible to my cats (nominally 50 Hz to 64 kHz). I think that a frequency of 30 kHz as a top end would work as it is guaranteed to be higher than a human can hear. Tones in the 20-21 kHz range are annoying to me because I can just barely hear them. I want the tones to be reasonable volume, meaning loud enough to match a normal conversation but not so loud as to be frightening for my cats. I am essentially looking to be in the same general range as an ultrasonic squeak made by a real mouse.
For the power requirements, I would like to be able to drive this directly off the timer1 circuit in an ATmega328. I am not using an Arduino specifically, but I am using the Arduino programming environment for the Pololu Baby Orangutan B (ATmega328). I'm trying to keep the whole thing very light. It's a very small robot driven by two tiny motors so it would be great to have something that is under 1 gram or so.
It seems that most manufacturers don't provide data for the frequency response curve above 20 kHz. Of course this makes sense with respect to human hearing, but for my application this is a bit annoying. Pui Audio makes a piezo that seems to be a possibility, but I am unsure if it will put out any reasonable amount of sound if I drive it up to 30 kHz. http://www.puiaudio.com/product-detail.aspx?categoryId=2&partnumber=AT-0927-TT-2-R#
Does anybody have any experience driving a piezo out of its normal range? The primary resonance for the above piezo (AT-0927-TT-2-R) occurs at 2730 Hz.