low-powersound
I am looking for a small, low power buzzer for my circuit. The components I found in the market do not fit my requirements. The piezo buzzers are too big (min diameter 9mm) while the electromagnetic one consume too much power.
Is there any other type of buzzer I can use? What is used in wristwatches?
While the processor itself supports very low-power modes the LM2734 Datasheet shows a typical quiescent current of 1.5mA. It is also only a step-down regulator so the Arduino Due shows a minimum operating voltage of 6V, but you'd really want to aim higher say by using 6 cells for 9V so it continues operating once the batteries are getting low.
If you used 6 x 1.5 AAA after a quick search the highest capacity I could spot was 1200mA/hr so that would give around 1200 / 1.5 = 800 hours or about a month of operation.
But that's only taking the main regulator into account, there's also op-amps and a secondary linear regulator along with a few resistor dividers. I do not know the exact answer but as a guestimate would say it's likely to be more in the order of 5mA (10 days of operation) and not really suitable for your intended purpose.
LCD display without back-light is the only possible solution on these conditions.
Something like this:
Here is some example data sheet: Link to PDF
Best Answer
Wrist watches probably use the 9mm ones, or even larger. You won't find them smaller, because they would hardly produce sound anymore. The actual piezo-electric ceramic is mounted on a diaphragm which flexes up and down as the piezo stretches or shrinks under voltage excitement. The piezo needs to have a certain size for this, otherwise there would be hardly any flexing, and no sound.