How much current would this draw?

I am trying to build and audio amp and i need to know what voltage/current my wall plug should be. It says it in the pdf i think but i need another persons opinion. here is the link to the amp, pdf is a  link on page.

Also would it be possible to feasibly power this for a short time on batteries (aa or c size?)

I know i am burdening you already, but what wattage resistors should i get?

P.S I am building off of figure 15 on page 7


sort by: active | newest | oldest
Its a 20W amp, and as Nacho says, 12V, 20W, call it 30, say 2.5 Amps.
Use 1/4 or 1/8 Watt resistors.

If you don't attempt to run flat out, it'll work fine on 12V worth of AAs.

astroboy907 (author)  steveastrouk7 years ago
Ok now i see it. Said it was a 12W amp in search box, but i guess thats just to the speakers (not to the circuit as a whole). Got to remind myself to read the datasheet better :)
I hope not to run flat out. It says minimum input voltage of 6v, though, so possibly i could run it (for a short while at least) on somewhere around 9? (reads the datasheet again to make somewhat sure)

Thanks steve and nacho!
. When shopping for amplifiers, it would be called a 12W amp. Most consumers are only worried about the power going toward making noise, not total system power. The amp uses 20W of power to output 12W to the speakers, but only nerds/geeks/hackers/DIYers/&c care about that figure. ;).
Yes, it'll run on 9
Just for future information,
Only class D amplfiiers consume only slightly more than the output rating. A and B consume quite a bit doing their job ? This is a class B amp.

NachoMahma7 years ago
.  12V and Ptot = 20W (page 2/12 of the PDF). I'd add a little headroom, so 25-30W should do it.
.  Verify with a real electrician before proceeding.
astroboy907 (author)  NachoMahma7 years ago
hmmm. i thought it was the drain current (page 3, 850ma for my application)
25w seems a little large for me, maybe i shouldnt build it :)
NachoMahma7 years ago
. I get a "Part not found." error when I click your link. :(
astroboy907 (author)  NachoMahma7 years ago
oh. here is the part #, just copy-paste into digikey search