That will save you an amount equal to ~ 1/2 the Piezo current. An additional similar capacitor right at the leads of the Piezo might be a good idea (if noise is coming from the piezo).īTW you can probably bump the 1k resistor in the base to the transistor to 5k or maybe 10k and still have enough drive for your piezo. Not sure if this is the case but a 0.1 µf or 1µf (actual value not critical) across the Mega supply might help. If the piezo is only drawing an estimated 6 or 7 ma from your battery it is possible at marginal voltages for the Mega noise on the voltage line from the piezo is causing the Mega to "reboot". One would expect lower current at lower voltage. The Max 9 ma specification is telling you, at the rated voltage it will not draw more than 9 ma. You do not need to add a resistor in series with the piezo device. Hi, I agree with Jiggly-Ninga, the piezo device is a self contained device. During our use, the typical lifespan should see the batteries drop to around 7.2v so we don't usually get all the way to the end of life voltage. They are 3.7v batteries so the average operating voltage is 7.4v for the pair. The batteries are in series and output 8.4v when fresh and shut off (end of life) at 6.6v. I was thinking that adding a capacitor to this in parallel would solve the problem, but I'm not sure how large of a capacitor to add. When the piezo is activated it will sound for a few seconds, but then the Arduino shuts off and then powers itself back on - without the piezo on. The piezo is a larger piezo and works fine when the batteries are fresh, but the intent of it is for it to be activated later in the lifespan when the batteries have been used for a few hours and the voltage is a little lower - not critically low, but lower. We're using an Arduino Mega board that has a number of components, but one section in particular seems to be giving us a problem and I suspect that is due to voltage drop when our piezo speaker is activated.
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