# Small piezo buzzer with low voltage, low current

I am designing a board which communicate wirelessly with a smart phone. When I send a specific command, I want it to sound an alarm to the user, making it able to be found when lost. My board runs on a coin cell 3V battery, which has a current drain which should not go above 15mA. The sound unit should not exceed 10mm in diameter. I struggle to find any speakers or buzzers which can operate within these conditions, so my question is:

What methods and/or components can be used with 3V, max 15mA circuit to notify a user using an audio signal around 70dB SPL?

• How many dB SPL do you need? – Andy aka Aug 13 '13 at 9:31
• @Andyaka I guess about 70dB – chwi Aug 14 '13 at 11:57
• An ordinary piezo disk should meet your electrical requirement while being fairly loud at suitable frequencies. Current demand will only be while voltage is changing, so be sure to have sufficient supply caps and to measure the time average. – Chris Stratton Aug 14 '13 at 12:42
• @ChrisStratton I thought that these disc needed around 30V? Do you have any examples? – chwi Aug 14 '13 at 13:47
• 70dB, at what distance is that? 10cm? 1m? (Without the distance the number doesn't mean anything) – Johan.A Aug 14 '13 at 13:53

The dimensions are 30 mm diameter, 20.5 mm height excluding leads. The Digikey pricing is $3.55 each, but you can find them on eBay sometimes for as little as$1 including international shipping.