[sdiy] Amp-in-a-chip

[Roy J. Tellason]

On Sunday 03 February 2008 23:11, Kyle Stephens wrote:
> Hello...
>
> I cannibalized some nice speakers out of a broken hifi
> set a while ago, with the intent to make a simple but
> quality workbench amp out of them. They are 4, 4 Watt
> 4 Ohm speakers, and I may get another bigger one to
> act as a subwoofer. So call it 20-25 total Watts tops.
>
> I've flipped through electronics catalogs and Googled
> around, and found a few single chip audio amplifiers,
> though I'm curious if anyone's done something like
> this before and if they had any advice. I'm fixing to
> scratchbuild a cabinet for the speakers and all.

I used to work on a bunch of stuff that had TDA2008,  TDA2040,  and STK086 (?) 
power amps in 'em,  which were often a lot of the problem but in those cases 
it was because the speakers were connected while power was applied (it was 
work for a rental place).  If you don't do that they're not that often a 
problem.  My TV has just had some minor issues,  though not involving that 
and I notice that there's an STK4362,  which the datasheet I just snagged 
(but haven't added to my site yet) also flags as a discontinued part.  It's a 
nice dual 10W amp.  There are a LOT of them out there.

Have a look at http://www.classiccmp.org/rtellason/by-mfr-number.html (it's a 
big page) at TDA numbers,  and STK numbers,  and use your browser's 
find-in-page search for "audio pwr amp" and you'll find plenty more.  
Depending on the efficiency of the speakers and enclosure,  you can get some 
surprising loudness out of not very much amp,  apparent to me with a board I 
built that uses only a couple of LM386 chips putting out about a watt each.

Don't try and run it at or near the maximum power supply voltage listed,  and 
don't try and push them to maximum output,  and many of these should work 
just fine.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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