3.3〜5VにS端子VCC出力にデジタルI / O出力。
動作電圧：3.3V - 5V
I had the same experience with this as Jastra. The pin labelling seems to be incorrect. When I connected signal to (-) and ground to (S) it worked. I have no idea what the middle pin is for.
I just noticed the labelling on the photo is opposite what it is on the one I received.
I'm done with HK for arduino stuff. I typically get cheaper, better quality and more accurate product info from China sellers on fleabay.Correction: If you simply put the (-) pin high (5V) and the (S) pin to ground (opposite to the product explanation) it buzzes well and pulls only about 25mA.The buzzers seem to work ok. The 5V channel seems to be unused though. Desolderd the buzzer, middle pin not connected. The (S) Signal and (-) pins are reversed. Mine only worked when I put signal on the (-) pin and ground on the (S) pin. Even with a 100Ohm resistor in series, it still pulled 50mA wich is too much for an Arduino Port. Resoldering the Buzzer 180deg would make the pins right.