Connecting 5 volt active buzzers in parallel or series

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bigjoncoop

Joined Feb 1, 2019
158
A friend of mine it just asked me if he was to put 2 active piezo buzzers/beeper in parallel or series if it would make "the beep louder"...

I think I'm overcomplicating it in my head.

The application would be on a quadcopter flight controller. The Beeper gets fed at constant 5 volts and the negative wire is connected to the beeper control pad on the flight controller....

He had asked if you would have wire the beepers in parallel or in series would it be twice as loud or would be the same just shared between the two? And if it was to be louder in either parallel or series would it be limited by the amount of current the 5v pad can provide?
 

Tonyr1084

Joined Sep 24, 2015
5,969
If the "Beeper" has its own frequency generator (tone generator) then you would want to put them in parallel on a 5V supply. The audible output would be louder, but not necessarily twice as loud. I would think more along the lines of 50% louder, as volume is a function of a square. For instance, a 1 inch square has 1 square inches surface area, whereas a 2 inch square has 4 square inches of surface area. With regards audio power - I could be wrong - to double the volume you have to quadruple the wattage.

But you mention a piezo. They can not be paralleled simply as parallel speaker elements as they are frequency dependent. Unless they are the exact same they will interfere with each other. Putting them in series would just about stop them from functioning all together. AND they would need twice the voltage supply. So series? No. Parallel? Yes - IF each beeper has its own electronic circuitry.
 

wayneh

Joined Sep 9, 2010
17,152
In series you have two operating at lower power than one alone, if it would work at all. I'm thinking of it like two resistors in series. The current through both goes down, as does the total power.

In parallel, the power doubles and two noisemakers are obviously going to be louder than one. They may not make the exact same frequency and thus will beat against each other. That tends to be even more ear-splitting.

A complicating factor is interaction. The driving circuit may not be as simple as a 5VDC supply. If the circuitry produces the tone, instead of the beeper, then it may struggle to provide the power to two loads.
 
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