Drive speaker with 3.3V in both direction.

Hello !

I actually use the ToneAC library to drive a speaker on my 3.3V project (arduino pro mini). The main advantage of this library is that two phase PWM pins are used in the push/pull manner. So we get twice the volume with the same current from the battery.

pin9 : 3.3V → 0.0V → 3.3V …
pin10: 0.0V → 3.3V → 0.0V …

But the sound is not enough loud (at 40mA with 3.3V). I would like to drive move current in the speaker. I don’t need sound quality. I just want to generate sounds at different frequencies.

There are many (complex) audio amplifier examples on the Arduino forum. But I don’t really want to amplify a signal. The input and output signals are all 3.3V square wave. I just want to connect the battery directly to the speaker. For example I only want the PWM part of a class D amplifier.

I have found some dual channels H-bridge chips. But they are all intended to drive motors.

Where I can find a classical small DIP chip (<8 pins), that operate at 3.3V, that can drive the current in a speaker, without additional components, in the pull/push fashion ?

Thanks !

Baptiste.

But I don’t really want to amplify a signal.

Yes you do. You need current amplification not voltage.

I have found some dual channels H-bridge chips. But they are all intended to drive motors.

Yes that is what they do.

Where I can find a classical small DIP chip (<8 pins), that operate at 3.3V, that can drive the current in a speaker, without additional components, in the pull/push fashion ?

Without additional components - nowhere. What is wrong with additional components? You need them to block DC from the speaker. DC in a speaker will kill or damage it.

Have you seen this one:-
Speaker.png

Thanks you Mike for your help !

When I say that I don't really want to amplify a signal I mean that I don't need to keep voltage proportionality between the input and the output as a classic amplifier does. I just need to generate constant amplitude wave.

The reason I don't want too many components is that the project need to be mounted on stripboard as compact as possible. The global project size is important.

https://github.com/prunkdump/arduino-variometer/ |500x418

And when the number of components increase, the number of needed tracks increase rapidly. Moreover I would like to make the project easy to build to DIY enthusiasts.

I know that DC is not good for speakers but it's often the way the speaker is connected in many arduino projects. From the ToneAC library page : https://bitbucket.org/teckel12/arduino-toneac/wiki/Home |500x303

I have found this low voltage H-bridge chip : L9110

http://www.elecrow.com/download/datasheet-l9110.pdf

The idea is to drive the speaker (with resistor) with the two chip's outputs controlled by two arduino's pins as in the ToneAC circuity.

It is not really AC but it generate a push/pull square signal.

Do you thinks it can works ?

Baptiste.

I have found this low voltage H-bridge chip : L9110

Yes. That should work.

When you turn the sound off, drive both pins high or both pins low so that no current flows. (And, maybe check the leakage current.)

Thank you very much !

I will try to make the circuit and I report here if it’s work !

Baptiste.