12V 2A power supply

Look for 12v 2 amp PSU on Ebay.

Oh, and just read the outside of the box (as opposed to the back of the device by the power socket).

This says power input DC 9-13.2V 4A. I assume this range means that it is suitable for automotive use as well as off a 12V adapter. However this may point to a 12V 5A power supply.

Or see what CPC have. 24 W is quite small, CPC have 60 W (5 A) and 120W (10 A) switched mode jobbies for not a lot.

What is the application you say "amp", for an amplfier to work well it wants a good regulated power supply that isn't going to sag when called on to provide it's rated current.

Owain

In the spirit of d-i-y, a 12V, 5A transformer, a bridge rectifier, a smoothing capacitor, and a 5A voltage regulator IC with heatsink. Add the box, and it shouldn't cost much more than a ready built car accessory PSU from Maplin, whose website appears to be inaccessible from here at the moment for some reason.

Back up now.

Why?

ll

CPC or Rapid.

If it's for audio, I would build my own linear supply.

MBQ

I presume you mean 4A or more

If you had a lot of time on your hands you could build somthing quite pictu= resque using 1920s technology. Perhaps a well polished breadboard with tran= sformer, motor rectifier, output synchronisation meter driving a big open r= elay, and a few large LCs to clean up the output. Wire it all with bare squ= are wire bent to square routes 1920s style, add a row of screw terminals an= d bare wire fuses, put an ebonite cover on the twisted pair mains connectio= n and you're done.

NT

Stereo amplifier, 20W RMS (10W per channel) into 4 ohm speakers.

Trust you to make thing unnecessarily complicated.

Owain

There's probably an adaptor or the bits to make one in the Maplin catalogue somewhere, if you look. Or just buy the right plug, cut the cigarette lighter socket off and connect the plug to the cable. If you don't have a multimeter, you'll need to spend an extra tenner to buy one. It would take me about five minutes, including getting the soldering gun out of the toolbox.

If all else fails, take it in to your local electronics shop and ask them for the bits you need. The power supply you linked to has either two banana plugs or a cigar lighter plug as output connections, so you're no better off with that one.

I can't help but wonder if there wasn't a cheap mains powered amp available that would not have required a separate power supply.

Chris

There are quite a few available online using the same chipset that include a wallwart from twenty to eighty quid.

Power amps don't normally have regulated supplies. But it obviously does need to supply the required current to give the rated power output - and preferably with larger than needed reservoir caps to handle transients.

That sounds like a bridge device designed to run off a car supply. As you can't get 20 watts into 4 ohms from 12 volts with a 'normal' amp. Unless you use an output transformer.

Which begs the question as to why you'd use this from mains - much easier to up the volts and use a conventional amp.

But if you do run it from mains, you need 13.8v - not 12. It won't give its rated output off 12v.

Presumably that is 20W output, so with ineffiencies the input power will be higher. I reckon a 24W supply would be hitting it's limits if the amp is driven flat out. I'd be looking at something that can deliver at least 40W without struggling.

For audio use a generously rated linear power supply would be better than a cheapy switched mode one. The latter can shove out all manner of muck that may not be audible but will interact.

Bit horses for courses though, I guess you are really only after something that will produce an acceptable sound rather than the ultimate in HiFi.

There doesn't seem to be much below £200 as a seperate with an internal power supply. You can get small (for various values of small) all-in-one systems in the £100-£200 range but I was looking for something minimalist, which this certainly is. Didn't want a standard size seperate. The reviews also compared the performance favourably with £200+ seperates, and the amp only costs £19.99. I am going to drive a couple of ceiling speakers so an investment in a hifi amp seemed a bit OTT.

You can get ones for not much more including a wall wart but again reviews have advised that the amp performs much better with a better PSU.

Which is why I am looking for a better quality PSU but trying not to spend more than the amp cost.

Amp and PSU for £40 then add a couple of ceiling speakers (not from a HiFi shop) for around £50 a pair and the kitchen has music for under £100.

Cheers

Dave R