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JCoffey 27th May 2003 06:58 PM

Anyone use Wall warts to run a gainclone
Just curious. I noticed that it can be used to bench test them, but I really am not very knowlegable with electronics building yet, and since this will be my first project, I want to simplify it as much as possible.

pinkmouse 27th May 2003 11:29 PM

Hi J

I'm not sure people have used wallwarts to test GCs, as they would need be dual rails, ie 15-0-15 to work properly, and most are just single rail,15-0 for example.

If you were sure they had no internal circuitry such as smoothing or regulation, you could possibly cobble two together, but the current would probably still not be sufficient to run the amp at anywhere near full power.

I would suggest you look around for electronics surplus suppliers, either locally or on the web, who could probably do you a cheap deal on a 18-0-18v 300VA transformer. This would work much better.

Good luck

leadbelly 27th May 2003 11:55 PM

If you can track down two old Aurora AFX slot car set wall warts in a surplus store, they might work. The big ones that came with the bigger sets were the heftiest I've seen, but unfortunately they did have a diode or diodes inside which you would have to get to somehow. I've got only one of the big ones myself.

Nuuk 28th May 2003 01:37 PM

I wonder how many peeps may have an 18v cordless tool (screwdriver etc) with a spare battery. The two batteries should be just sufficient to test a Gainclone with 18-0-18 volts.

JZatopa 28th May 2003 10:20 PM

what kind of power do laptop chargers put out? Would those work?

pinkmouse 28th May 2003 11:20 PM

I suspect they would be undervoltage for a GC, probably not enough power, and definately far too noisy to work properly, sorry!

cm961 29th May 2003 02:58 PM

I scored an old printers power supply which I believe is 20-0-20 AC and 3 Amps or something. Its not really a wall wart though as it doesn't give DC. I think its basically just an external transformer, maybe it has fusing too. I plan on using that.


Petter 29th May 2003 03:40 PM

Re laptop chargers:

Laptop chargers typically give out:

Newer Compaq units: zero and 18.5V at 65W
Not quite so new Dell units: zero and 20V at 70W.

So as you see, these are quite interesting as power supplies go. The problem is that they are not bidirectional. I suspect they are floating though, so two units hooked up the right way will double power AND give you a split supply if that is what you are after. I have a few power supplies kicking about, and have been toying with doing something like this for a while.


jackinnj 29th May 2003 05:16 PM


Originally posted by Petter
Re laptop chargers:

Laptop chargers typically give out:

Newer Compaq units: zero and 18.5V at 65W
Not quite so new Dell units: zero and 20V at 70W.

Laptop chargers are off-line switchers -- they should work -- but make sure to wrap the cord through a torroid -- this will stop some of the switching transients from permeating through.

You will occasionally see +/- 24 Volt Lambda linear supplies on EBay. I use one of these to test some of the LM3886 LM1876 LM3875 type amps. There was a beast which went bidless last week, starting price was $49.

You will very frequently see 24V/3 amp Power-One, Artesyn, Lucent switching supplies on EBay for dirt cheap prices -- this due to problems in Telecom.

JCoffey 29th May 2003 06:07 PM

Interesting. I have quite a few compaq laptop power supplies laying around. Something to look into. Build a couple Monoblocks with laptop cords connected to them.......

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