SPEAKER or BUZZER? AC? DC? VOLTs? AMPs?

[gary350]

Is this a buzzer or speaker?

Google search for Printed circuit board buzzer or speaker shows advertisements not related to this. Also PCB for speakers.

EBAY search shows lots of PCB speakers and buzzers but none like this. Closest 1 that looks like this has 3 wires, 1.5v, 80 micro watts

 

[rjenkinsgb]

It's just a piezo transducer disc, plus some sort of casing.

It can be used for either, with appropriate electronics to feed a suitable signal - either single frequency in a "buzzer" or audio.
They are also used as sensors in such as electronic drums.

They generally have a very limited frequency range when used as speakers.

eg.

Passive Copper Piezo Buzzer Disc Trigger Alarm Sounder Drum Sensor Transducer | eBay

Sound Transducer Type: Piezo. Height: 0.3mm With cover.

www.ebay.co.uk

https://i.ytimg.com/vi/5JHuVeG7dv8/maxresdefault.jpg

 

[gary350]

I think this circuit board may have come from a microwave that I stripped for parts once.

So this device needs a frequency to make sound. I was hoping if it is a simple buzzer like a bicycle horn 1.5v will make it buzz. Is there a data sheet on these devices. Doing online search ebay has best information they say, 1.5v to 6v another buzzer says 1.5v to 15v another one says 1.5v to 28v. Input signal must be AC or pulsing DC. I found information that says one device is 80mw output wonder if a person can even hear that. After searching for buzzers I notice I have 2 other type buzzers that I never knew are buzzers little black plastic things 3/8" diameter with pencil size hole in the top end.

 

[Nigel Goodwin]

The piezo discs are pretty loud, you just have to drive them at the right frequency - about 2.5KHz usually.

EPE did a freezer alarm many years ago using a PIC 12C508 (before the F versions came out), which I built just as a matter of interest. I modified the design and software slightly by removing the ground connection of the piezo and connecting it to another I/O pin, and driving it bridged. And while it was fairly loud before, it was a LOT louder with the extra drive from bridging.

I sent the details off to EPE, and they printed the mods a couple of issues later.

Anyway, presumably you have a microwave oven?, does it beep?, can you hear it? - it almost certainly uses an identical piezo, and only fed single ended.