Help with Audio amplifier and speaker for Robot

Searider

I feel quite at home with digital circuits but could use some advice with a analog question or four.
I am planning to use the Vinculum VMusic2 as a source for sound effects for my robot. I can control the VMusic2 from the propeller easily enough. My question is about how to amplify the sound to be heard byt people standing nearby the robot. I can easily find any number of audio amplifier circuits from 1watt to 100watts and more. Here are some specific questions but please if anyone has any general advice please feel free to share.
1.······ How much power do I need to be able to make the sound load enough to be heard a few feet away (say 10')?
2.······ What criteria do I use to choose between 4ohm or 8ohm speakers?
3.······ Most (all) of the audio amplifier circuits that I have found require a positive and negative power rail. Is this really a requirement for Audio amplifiers or should I keep looking for a circuit that can use my easily available 5v, 9v, 12v or 24v
4.······ If I do need a +/- power supply, can I do something like tie the negative rail to my system ground (0v) the neutral to my 5v rail and the positive rail to my 9v supply?
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Thanks for any thoughts, advice or suggestions.

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Searider

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PJAllen

Here's an "8W" amp IC, which could be distressingly loud,·that runs from a single-ended supply --

http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=9046

Here's the datasheet, examples toward the end --

http://www.datasheetarchive.com/pdf-datasheets/Datasheets-11/DSA-203543.pdf

If you need stereo, buy two.

Post Edit -- radio shack still sells this handy item

http://www.radioshack.com/product/index.jsp?productId=2062620&cp=

Post Edited (PJ Allen) : 10/27/2008 12:18:22 AM GMT

Brian218

You could also use a LM386 audio amp. There's a data sheet on the 1st link

http://www.mouser.com/Search/ProductDetail.aspx?qs=GxHLpfBOhnkNAvtEWkr//Q==
http://www.radioshack.com/product/index.jsp?productId=2062598&cp=
http://www.allelectronics.com/make-a-store/item/LM386N/LOW-VOLTAGE-AMP/-/1.html
http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=10500

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This post is a work of art. Variations in spelling and grammar are intentional, artistic endeavors that add value to all of mankind.

Post Edited (Brian218) : 10/27/2008 12:50:24 AM GMT

Desy2820

Depending on the size of your robot, a set of computer speakers could also work.· Try and find a set whose input voltage matches the voltage available on your robot.

Searider

Wow, thanks for all the great ideas and information.

I am sure I will have the sound working soon based on this.



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Searider

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Dr. Resonance

I use the TDA series audio amp chips.· They only require·10 ·additional parts and run in any value output (depends on buss voltage) to provide up

to 12 Watts of audio power.· A simple 10K pot on the input side of the chip will provide complete volume control.



I use the TDA2003 and it works great --- I run it around 6 watts with a pot on the frontend.· I also have the schematic --- contact me off-list at resonance@wildblue.net if you need it.

Dr. Resonance