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Author Topic: interfacing with a speaker  (Read 16456 times)
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Is there an easy way to get more volume out of a speaker than from an arduino pin?

My son is 8 and is now playing drums... he needs a metronome.  What to do?  Well I could buy one... or I could grab some stuff out of my junkpile... and an arduino to make one myself.

I'm pleased to say I have breadboarded a very nice metronome, with an lcd display, adjustable contrast, and adjustable tempo, 40-240 BPM.  the arduino LCD and tone libraries, combined with analog in made it very easy.

The one problem I am having is, while the tone, and the timing sound great, it needs to be LOUD!!!!  I'm driving a small 8ohm speaker from the shacks electronics section off of an arduino pin... but I think 40 ma at 5v is not enough.

Can you guys suggest a way to make this baby louder before I try to mount it in a box... It just won't be useful, if he cant hear it over his playing.


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You really should not wire a output pin directly to a 8 ohm speaker, it does put the output pin under a lot of stress and could damage it. What you need is a simple small audio amplifier. There are several ways you can go.

The simplest would be to find some used computer speakers. These accept a line level input and have a built in speaker. To wire to them take a .5ufd cap and wire from the output pin to the line in signal connection and also wire from arduino ground pin to the line in ground connection.

There is also the basis for a DIY amp on reply #3 in the following thread:

If you were to use that circuit just remove the mic and R1 and wire the left side of capacitor C1 to the arduino output pin and run a wire from the arduino ground pin to the amp's common ground.

Of course you could always wire your output pin to your home stereo, again using a series cap and running a common ground wire. Does anyone but me still own home stereo equipment.  smiley-wink

« Last Edit: January 23, 2011, 09:38:18 pm by retrolefty » Logged

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I still own home stereo! In fact, Dynaco tube amp, sourced from CD player, driving JBL tower speakers.

However, for arduino sound, I use this.
Speaker was $1.49 from, 90dB,  very loud if needed.
Rest were parts I had. TO220 style N-channel MOSFET.

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at
Arduino for Teens available at

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