# How to power lights and accessories only



## BionicJcs

Im still trying to find some kind of power pak that would be just for a/c accessories like the building lights and streetlights. No one seems to have something just for that. Everything that I see is an analog ho power pak with throttle and only about the 1 amp a/c accessory terminals. I called several "train" stores, and it is surprising how little they know about what they sell.

So Im appealing to one of you fellows who knows how to do this stuff. I am building a pretty big layout, an around the walls deal, 24 x 12. Ill have quite a lot of buildings and signs and lights, and I really want to be able to light up to 50 bulbs or more. I have about 5 lights on right now using my 53 year old transformer a/c terminals which gives one amp. What am I going to need? Somebody at the hobby shop said I could run the lights from the track side of an analog pak, using the throttle for a rheostat. That doesn't sound bad, if the pak would be what, 5 or 10 amps? I just need education on it

PS, Im running dcc only and not using tracks for accessory power.


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## New Berlin RR

just take another DC power pack hook your lights and what not into it and then just set the dial/lever to about 50% and you should be ok, I know with the O scale and mainly G scale we can do that and be done with it...never tested on HO scale tho  but should work the same I think...


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## BionicJcs

Thanks for that input. Yes i can do that, but my concern is I don't know how much output amperage I need to run lots of lights.


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## johnd603

Ummm - this might be a strange suggestion, but - I'm using an old laptop power supply rated at 15 Volts - 2 Amps output to run all my switches. I don't have any lights or anything (yet  ) - but these power packs are usually tossed out with dead notebooks and electronic equipment and can be had for nothing - and can certainly be found in your required amperage for about the same price  ...

Hope this helps!

John


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## gunrunnerjohn

You need to add up the consumption of the lights and figure it out. Asking about the power for a "lot of lights" is akin to asking "How long is a road?". Nobody can tell you how much power they consume without knowing the details.

If the power to run "a lot of lights" is excessive, consider converting some or all of the lighting to LED lighting.


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## BionicJcs

Was only looking for an average or generalization. About 50 12 v lights, whatever they draw. I thought somebody might know having gone through it. Looks like I have a lot of work to do on my own thanks


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## cv_acr

Try something like this:
http://www.powerstream.com/12-volt.htm


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## waltr

Measuring the current draw is not that hard with a little help from Ohm's law, E = I*R. 
Insert a small value resistor (0.1 to 2 Ohm depending on the total current, try to keep the voltage drop across the resistor below about 5% of the supply voltage) in series with the loads an apply power. Then use your Voltmeter (DVM) and measure the voltage across the resistor (DC setting for a DC supply, AC setting for an AC supply).
Now you know R (Ohms) and E(Volts) in Ohm's law so simple math E/R = I(Amps) give you the total current draw of the load (lights, etc). The better the precision of the resistor the better the current measurement but for most purposes 5% is close enough.

For powering lights, etc there are tons of Wall warts around that used to power or re-charge various electronic devices. Check surplus and thrift stores, your and your friends closets for un-needed wall warts (they always out last the electronic gadget). These are typically have outputs from 5 to 16V, 200mA to 1.25A and can be AC or DC.


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## gunrunnerjohn

The typical 12 volt bulb draws about .1 to .15 amps. Fifty of them would be pulling 5 to 7.5 amps, so a little wall wart isn't going to do the trick here.


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## oldSmokey

gunrunnerjohn is quite correct in what he is telling you, you just cannot say a number of lights etc, it all comes back to what amount of current you will be drawing.

What I did was to buy one if these:

http://www.ebay.com.au/itm/Universa...Electrical_Test_Equipment&hash=item3a6ad3c244

I then run a DC bus all around under the layout a few inches away from the DCC bus so that I could pickup from just about anywhere on the layout. These power supplies are switchable on the input 110v - 240v, I'm using 240v here and as I have a 10A unit, I'm not using anywhere near that current as my layout has only Leds no bulbs whatsoever.
For $18.19 you can't go wrong.


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## waltr

With several Amps of current required, oldSmokey's suggested power supply is a good way to go.

Although without actually measuring the current draw one is just *Guessing *what is required. The 12V lamps I use for HO scale buildings only draw 30mA so 50 in parallel would be 1.5Amps which could be supplied by two Wall Warts (one two separate circuits).


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## BionicJcs

Well GRJ finally got my point and gave me something useful. About 10 or so bulbs per amp. Useful info. I have a line on a 4 amp a/c accessory only pak for about 28.00. Now for my next question. If Im using a 4 or 5 amp power source, and don't max it out right away ( 5 lights) , do I need to rheostat it down, or will it only use that it needs to?


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## oldSmokey

Hi BionicJcs,

It will only use what it needs, (current that is) so there is no need to rheostat it down, but do take notice what gunrunnerjohn said, don't guess what current is being drawn as different bulbs draw different current loads.


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## gunrunnerjohn

All you have to do is make sure the voltage is proper for the lighting in question, the current takes care of itself.  After all, your 4 watt nightlights don't try to draw 15 amps from your 115V socket, right?


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## manchesterjim

gunrunnerjohn said:


> All you have to do is make sure the voltage is proper for the lighting in question, the current takes care of itself.  After all, your 4 watt nightlights don't try to draw 15 amps from your 115V socket, right?


And just to pile-on to what GRJ is saying here.....if you happen to have enough lights to exceed the current rating of the supply.....you'll likely see the lights dim.....or perhaps blow a fuse in the power supply

Jim

p.s. A handy diagnostic tool I use is a technique called "letting the smoke out"  ....but you should only use this one if you have some experience in electronics! :laugh:


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## Southern

manchesterjim said:


> p.s. A handy diagnostic tool I use is a technique called "letting the smoke out"  .. :laugh:


 
If you run out of wire smoke, Lucas Electric sells it. It comes standard on old English cars.


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## manchesterjim

Southern said:


> If you run out of wire smoke, Lucas Electric sells it. It comes standard on old English cars.


I think I may have run across them many moons ago! I got my hands on an old Triumph Spitfire....1971 I think.....in addition to throwing a rod on its maiden voyage....I later had some mysterious electrical problems, including some smoke-letting!


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## gunrunnerjohn

Lucas, the _Prince of Darkness_.  I own an old Jag.


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## BionicJcs

*TS*

I kind of thought all that, but wesomebody said I would have to turn it down if not using all the power. didn't make sense. I'm good now, and I don't have a problem waiting till dim time to add yet another unit. Thanks to all on this


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## gunrunnerjohn

We live to serve.


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## New Berlin RR

gunrunnerjohn said:


> We live to serve.


We do???? I thought we lived to assimilate others into the RR fanatics...err....modelers we are....



gunrunnerjohn said:


> Lucas, the _Prince of Darkness_.  I own an old Jag.


Have you beat (kinda)...BMW...well parents had one it just finially decided to blow its motor and its not worth fixing so off to the parts yard it goes...hopefully to help other BMWs live on...




manchesterjim said:


> I think I may have run across them many moons ago! I got my hands on an old Triumph Spitfire....1971 I think.....in addition to throwing a rod on its maiden voyage....I later had some mysterious electrical problems, including some smoke-letting!


OOPS!!!



Southern said:


> If you run out of wire smoke, Lucas Electric sells it. It comes standard on old English cars.


Can say the same for german (old) cars and some early electronics...tho I have a 486 and a 386 pizza box still kicking away....I have only done smoke letting on an old PSU that was intentional tho...




manchesterjim said:


> And just to pile-on to what GRJ is saying here.....if you happen to have enough lights to exceed the current rating of the supply.....you'll likely see the lights dim.....or perhaps blow a fuse in the power supply
> 
> Jim
> 
> p.s. A handy diagnostic tool I use is a technique called "letting the smoke out"  ....but you should only use this one if you have some experience in electronics! :laugh:


really...and I thought it was a good idea to keep the magic smoke bottled up...oh wait that was just steam never mind....


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## norgale

You can use more than one transformer too. Just break the lights up into smaller circuits.
If you use the track side of a transformer then you can dim the lights or make them brighter by turning the throttle up or down. For constant light level then use the accessorie side of the transformer. Pete


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## BionicJcs

Yes, I think I have a good handle on this now. I plan to have a lot of lights and other things, and probably will need two 4 or 5 amp paks when i get there. One thing I did, is I have a 24 circuit terminal distribution block. Its from the a/c side, and then Ive got 25 mini off on toggles I can put on whatever circuits, so to be able to turn on and off different blocks of lights etc.


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