Piezo Buzzer vs Normal Dynamic

I'm working on insect attractor project and I'm looking for a way to produce ultra sound. First I was planning to buy a piezo buzzer, but I simply couldn't find a way to buy one without paying ten times of its cost for delivery. I can easily go buy a normal dynamic in local electronics market. Is it suitable for producing ultra sound using Arduino Uno? If so, do I need extra parts like shields, separate power sources, transformers, etc.?

A normal dynamic tweeter may extend into the ultrasonic range. In either case, you'll have to check the specs.

But, since you can only safely get 40mA from the Arudino, you can't directly drive a 4-Ohm or 8-Ohm speaker without an amplifier (or at least a transistor or MOSFET). ([u]Ohm's Law[/u])

A piezo transducer has electrical characteristics similar to a (low value) capacitor and it (usually) has higher impedance at it's operating frequency compared to a regular speaker.

Note that a "buzzer" or "beeper" has a built-in sound generator circuit that makes noise when you apply DC voltage and you can't change the frequency. A piezo "speaker", "tweeter", or "transducer" converts the applied AC signal to sound. You need a transducer. But, if you buy the cheapest thing you can fine on eBay it may not be described accurately.

DVDdoug:
Note that a "buzzer" or "beeper" has a built-in sound generator circuit that makes noise when you apply DC voltage and you can't change the frequency. A piezo "speaker", "tweeter", or "transducer" converts the applied AC signal to sound. You need a transducer. But, if you buy the cheapest thing you can fine on eBay it may not be described accurately.

I didn't quite get that part. I know I can produce various sounds with piezo buzzer using Tone(). Is it different when it comes to normal dynamics? If only problem is getting enough voltage to it, I could just use a separate power source and a transistor.

Any idea what frequency insects respond to? (I didn't know they did)........

a dynamic HIFI tweeter could well have a response up to 30kHz . piezo could well go much higher - check the specs.

In either case to get a high sound pressure level you will need an external amplifier.

regards

Allan

allanhurst:
Any idea what frequency insects respond to? (I didn’t know they did)…

Not all of them do, but some use ultrasound for communication when looking for a partner. I’m planning to use it with an IR lamp to cover most of local insects, but first I need to get into sounds.

If you've ever been to the west coast of Scotland in early summer you'll have soon discovered that midges are an absolute pest! ( particularly if you're camping, as I was.... ).

I heard of a clever idea for a trap. It combined an ultraviolet lamp with a small propane flame, which of course produced CO2.. an attractant ( I wondered how the b*****s found me!)

There was then a small fan which sucked external air though a porous bag - like a vacuum cleaner - which was impregnated with insecticide.

Apparently this gadget could clear an acre, and in the morning you could empty out several 100g
of dead midges...

I want one!

Add your ultrasound widget and I reckon it could be even better........

regards

Allan