# Help ! which arduino should I choose?

I have this school project were I have to create a wall of 50 speakers by using arduino... And I have no experience of using arduino or speakers or anything, so I was just wondering which arduino should I choose? And what else do I need ? Any Ideas ? :) :) :) The Idea of the project is that I should be able to controll the speakers and to be able to choose the speakers that I wanna use and form "shapes" with them.. I would be really thankful if anyone can help me with this or give any ideas or anything !

Thank you!

...R

I know it sounds weird but there is a purpose for this :) anyway the problem is that we have to find a way to controll 50 speakers individually at the same time. The speakers will play the same sound, something very simple. And we will propably start by using only one arduino and 5 speakers and if we get it work we will try to do it with 50 speakers . But we are so beginners in thid area that we dont know what arduino should we choose and what other equipments we need etc.. so if anyone has any ideas I would be very happy to hear it! :)

Do you have an amplifier for each speaker?

I don't know should I get it ? we use speakers that are 0.25 W and 8 ohms.

Arduino can't drive an 8 ohm speaker directly - that overloads the output pin. You would need at least a 220 ohm resistor in series to keep the current from exceeding 20mA, which makes for a very faint output, just a few milliwatt. To get 0.25W from the 8 ohm speaker, you need more current. Power (watts) = I*I*R, so Sqrt (P/R) = I = Sqrt (0.25/8) = 175mA for max volume. If all 50 are playing at max volume, then you can see the current starts to add up.

If the speakers are only playing 1 at a time, and you just want to move the sound around from amplifier input to amplifier input, then a few analog switches can be controlled by an Arduino to do that. Look at a part like DG406, a 16 channel analog switch, also DG408 or DG409 for 4 or 8 channel. http://www.digikey.com/product-search/en?pv69=80&k=dg406&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

marinnnej: The speakers will play the same sound, something very simple.

Do you mean that there is something that generates a sound and you just want to use the Arduino to select which speakers play the sound?

I wonder if that could be done by using the Arduino to switch a transistor on and off thereby making or breaking the circuit between the sound and a particular speaker.

...R

Yes that is the idea. I am also working on this project :) For now we only focus on using 5 speakers.(the ones we found for now were 8ohm .25W) It does not have to be very loud but it has to be hearable. I thought to connect the 5 speakers with resistors in parallel to the 5V port, and indeed using a transistor for each speaker to make them turn on or off, where they can also be active at the same time.

But if I understand correctly doing this would only divide the already weak current again over the 5 speakers, and make it not really hearable at all?

Are you said working with project of Directional sound