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Hi all,

I'm looking for some advice:  I purchased a generic 5amp 12v DC transformer to drive a lot of accessories.  Lately while doing other work under the layout, I happened to pick up the brick and it was HOT.  My first thought is that perhaps I've somehow overloaded it or that it's nearing capacity, so I checked amperage with a multimeter.  With everything on it's pulling roughly 3.2amps.  

So now I'm wondering if this transformer is a cheap piece of @#$@# that needs to be replaced with something better.   The wires/connections are all normal temp.

Any thoughts or similar experiences?  If replacement is in order, any recommendations ?   I purchased the current transformer off of the popular "overnight" instant gratification service.

-Scott

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I'd say it is probably overloaded.  It may not be capable of actually pumping out anything like the nameplate rating.  Is this a switching power supply or an old fashioned iron core transformer?

You want tons of 12VDC that won't overheat?  Take an old PC P/S and use one of the breakout terminal strips.

I bought a pair of these for $10 on Amazon, they work fine.  I had several old ATX power supplies laying around that were too anemic for modern PC's, but 400 watts is plenty for what we do with model trains.

This is just one of tons of options.

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I have been using one for years. It powers over 25 buildings, crossing gates and signals, 3 smoke units, and under layout lighting. I use the 5 volt tap with a diode for 5 Miller signs. I use 2 feeds, each with a 3 amp breaker to protect small wires, and get to about 5 amps total with everything on. I use the same common as the AC transformers for the track.

An Amazon example:

There is a 600 watt for $10 more. They also have lightning fast circuit protection. I did mine before I found the adapters that @gunrunnerjohn mentioned, but put some together with  them and sold them here.

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@ScottV posted:

@gunrunnerjohn it's a ubiquitous brick style switching power source

unfortunately any old PCs have hit the trash a long time ago, but that's a great solution

Many of those cheap Chinese switching bricks have very optimistic ratings, a rule of thumb is they're really good for no more than half the nameplate rating, if that.  If you have one rated at 5 amps, you'll do well to get more than 2 amps out of it.

I use this little switcher, the ad copy says 3 amp rating.  However, on the bench, by the time it gets to one amp, it's already getting close to 100C, three amps is a pipe dream!

For a power supply that will power everything you can imagine, here's one that has +5V@20A and +12V@45A for $34 shipped free from Amazon.  Mate it with the breakout board I mentioned earlier and you have a power source you're not likely to overload!



<click graphic to expand>

___power

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@Woodson posted:

Silly question perhaps, but do the other leads coming out of the power supply have a function in the model railroad environment.. If not, what do you do with extra leads, just tape them out of the way?? TIA

The 24 pin connector has all the useful voltages, however you could use the other leads with the same voltages if that works for you.  The other leads mostly have the 5VDC and 12VDC power on them.  Obviously, you'd want to provide circuit protection as the power supply is capable of delivering hundreds of watts to an individual lead.

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