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12 Volt DC power supply (screw terminals)?

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  • Member since
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  • From: Anaheim, CA Bayfield, CO
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12 Volt DC power supply (screw terminals)?
Posted by Southwest Chief on Tuesday, November 01, 2011 2:37 PM

I have been looking around for a power supply (transformer) that you can plug into the wall and the output is 12 volts DC, and also has screw terminals.

This is for my town lights.  I have them all tied together via main power lines under the layout board.  Basically just like a bus for DCC.  I would really like to keep the wiring simple and not have to split up the town light bus wires and have multiple wall units.

Looking at various sources, I've found lots of 12 volt DC wall mounts with screw terminals.  The only problem is most seem to be rated at 500ma (or 1/2 watt).  I'm worried that this is not going to be enough wattage to handle all the multiple lights on the layout.

Has anyone found a good power supply that has a 12 volt DC output with screw terminals that also has enough Watts to handle multiple bulbs on a layout?

Matt from Anaheim, CA and Bayfield, CO
Click Here for photos of my train layouts

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  • From: Charlotte, NC
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Posted by Phoebe Vet on Tuesday, November 01, 2011 2:48 PM

You can buy such a transformer at most electronics suppliers, but a lot of people use desktop computer power supplies.

Dave

Lackawanna Route of the Phoebe Snow

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Posted by wjstix on Tuesday, November 01, 2011 3:20 PM

Keep in mind running 12 volt bulbs at 12 volts will make the lights unrealistically bright, and cause them to burn out sooner. I use an old DC power pack from MRC to power lights, and find it usually looks best at about 2/3rds full power.

Stix
  • Member since
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  • From: Pennsylvania
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Posted by nedthomas on Tuesday, November 01, 2011 4:31 PM

500ma at 12 volts dc would be 6 watts. Still not a lot of pwer.

Did you consider just using a xfmr and running the lights on AC.

  • Member since
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  • From: Reading, PA
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Posted by rrinker on Tuesday, November 01, 2011 5:31 PM

 If you found a suitable power supply but it has wires instead of screw terminals, just us it. Get a 2-position terminal block. Screw the transformer wires to one side, and you now instantly have screw terminals to attach the layotu wiring to.

                      --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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  • From: Anaheim, CA Bayfield, CO
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Posted by Southwest Chief on Tuesday, November 01, 2011 7:03 PM

Should have clarified a bit.

Most of the bulbs are 16 - 18 volt.  But I prefer 12 as the power supply.  And I much prefer DC for bulbs.

I haven't found any non screw terminal version with a lot of amps either.  But using a terminal strip is a super easy solution if I can't find one with screw terminals on it.  In fact I have lot of terminal strips for the building lights.  Makes it very easy to replace bulbs if they ever burn out.

I have used a power pack transformer in the past, but I was hoping to clean up the wiring a bit.  The MRC transformer I have been using has a 20 volt fixed output and that required lots of resistors Tongue Tied  I don't trust using the variable output.  If I happen to bump the throttle all the bulbs could go out pretty quickly.

Matt from Anaheim, CA and Bayfield, CO
Click Here for photos of my train layouts

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  • From: Eastern Shore Virginia
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Posted by gandydancer19 on Wednesday, November 02, 2011 10:36 AM

One of the things that you sort of need to do is figure out how much current all of your bulbs require.  This will then tell you what size of power supply you need.

Assuming that your bulbs are wired in parallel, find out how much current each bulb draws.  Usually this is on the package of the bulb.  You shouldn't have to measure them.  Anyway, find the bulb that uses the most current and multiply that by the number of bulbs you have.  If each bulb draws 20ma (0.020 amp) and you have 12 bulbs, 0.020 times 12 equals 0.24 amps or 240ma.  In that case, a 500ma 12VDC supply would work. (1 amp = 1000ma.)

Once you have the current figure of all the bulbs, then you can look for a wall-wart or other DC supply that can supply that amount of current or a little more.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

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Posted by modelmaker51 on Tuesday, November 08, 2011 4:46 AM

If you afraid of nudging the throttle knob, just remove it. You're not likely to move the shaft of the pot unintentially.

The older knobs have a set screw in the side, the newer ones just pull off, you can still adjust the pot with your fingers.

  • Member since
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  • From: Bedford, MA, USA
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Posted by MisterBeasley on Tuesday, November 08, 2011 6:21 AM

I have several like this one:

http://www.allelectronics.com/make-a-store/item/PS-6012/12VDC-5A-SWITCHING-POWER-SUPPLY/1.html

Mine are 4 amp.  They come with coax plugs, not screw terminals, but it's simple enough to clip the wire and attach it to a barrier strip, or you could get a matching jack, wire that to the barrier strip and then you'd have a plug-in unit.

A word of caution about these low-cost supplies:  They do not have circuit breakers.  Instead, they have a one-time fuse, and the units are sealed so the fuse is not really replaceable.  Protect your investment with a cheap fuse block and fuse from Radio $hack, or order them from the supplier when you get the power supply.  Trust me.  Eventually, even those 30 milliamp bulbs add up, and before you know it you'll be pushing the limit of whatever supply you buy.

It takes an iron man to play with a toy iron horse. 

  • Member since
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  • From: Anaheim, CA Bayfield, CO
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Posted by Southwest Chief on Wednesday, November 09, 2011 3:49 PM

Thanks Mr. Beasley.

Exactly what I was looking for.  Should be easy enough to cut the coax.

Matt from Anaheim, CA and Bayfield, CO
Click Here for photos of my train layouts

  • Member since
    December, 2004
  • From: Bedford, MA, USA
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Posted by MisterBeasley on Wednesday, November 09, 2011 4:19 PM

Order the fuse block and some fuses at the same time.  I'd go 1 amp below the rating of the power supply.

I was doing some wire testing a couple of weeks back.  I was trying to find a loose wire, so I had the power on.  Poof.  I shorted some wires.  Thanks to the fuse, I was back up with only the small cost of a fuse lost.  Even if you're careful not to overload the circuit with too many bulbs, one careless touch of wires in all that rat's nest that most of us have for under-layout decor can toast a supply.

It takes an iron man to play with a toy iron horse. 

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  • From: North Dakota
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Posted by BroadwayLion on Saturday, November 12, 2011 10:31 PM

Here is the one the LION bought. But he uses it to run his trains not for his aux power.

The aux power supply is home built using two transformers, two rectifiers and has -12, +12 and 24vd dc outputs. Musta cost under $20 in parts.

 

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

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