# The lights on my layout are very dim

Discussion in 'FAQs' started by Insey, Apr 1, 2005.

1. ### InseyMember

Thanks That reaffirms my suspicion that the problem lies with the load somewhere. I guess we'll have to wait and see when my shipment of new lights gets here to be 100% sure. If that doesn't work, I think it's time to quit my hobby of model railroading.
2. ### PeteMember

That's 17 volt amps....17 volts at 1 amp output. That's pretty light-duty for what you're using it to do. It will only handle 15-20 bulbs.
3. ### InseyMember

Ooh ok...that makes more sense.

So we are back to the problem being with my power pack again?
4. ### InseyMember

Btw, if I decide to switch over to DC, what happens when I have a light bulb with two black wires? How do I know which is positive and which is the ground?
5. ### PeteMember

It won't matter...a light bulb is not polarity sensitive like an LED would be.
6. ### InseyMember

Oh ok...but how come the accessory output on power packs is always AC?
7. ### InseyMember

One more question, how come when I put my volt meter on 20A, I still get a reading of 0.01 for the output of my power pack?
8. ### InseyMember

Btw I figure I might as well post a picture of my train layout so you can get an idea of the size of it:

10. ### ezdaysOut AZ way

Now we're starting to make sense. 17 amps and 17 voltamps just aren't the same. As Pete says, your only putting out one amp at 17 volts, not seven amps.

Now this other supply you're talking about. You have to be careful about the volt-amp or watt rating. It say 130 watts sustained, but it doesn't say which output that is for, so you have to assume it means total. Just as an average, you probably are getting about 8 amps at full voltage. That means if you are using four amps for rail power, you only have 4 amps to run accessories. These numbers aren't exact since they don't rate each output individually, just total power.

If you have a short, it has to have some resistance otherwise none of your lights will light. I still think it due to an underpowered power source.
11. ### InseyMember

Ok thanks. So then since my lights do indeed light up, my problem has to be the underpowered power pack. So do you suggest I just run several cheap power packs in tandem and then have my good Atlas power pack reserved just for rail?
12. ### ezdaysOut AZ way

You can really run your accessories (lights turnouts and other non-rail devices) for just about any source that I mentioned earlier. You don't even have to care what it looks like since it can be out of sight. I'm using a cheap Bachmann power pack for one accessory function on my layout, and the output from my MRC's for other stuff. When I get to the point that I want to light up my town, I'll probably add another cheapie power pack just for that. I've also got a couple of old supplies from some computers that I junked, and they may be put to use somewhere on my layout of I need them.

Just one thing, be careful no matter what you do that you supplies are protected from overload because some of them will get hot rather than just "foldover" (go to zero on overload) and can cause damage, and possibly a fire. Others have warned you about this, and it is a risk with using cheapie supplies. You can add a small fuse in the lighting circuit that will match the power supply's current output limit.

What is happening on "overload" is that as the current load increases, the voltage drops to compensate for it, making the lights dim. The power pack has a limited output measured in watts, and watts are calculated by multiplying the volts times the current. As the current goes up and the power limit is exceeded, the voltage will go down to compensate, even in a regulated supply. This extra current will cause the transformer and other components to overheat. As a transformer gets hot, it windings melt the insulation and things get hotter and your stuff starts to smoke.

I' not trying to scare you, just letting you know some of the basic reasons why it is not a good thing to overload a power supply.
13. ### InseyMember

Well good thing all my power packs have overload protection. I am about to bid on a Radioshack AC-DC 14V transformer that is going to power my 14V street lights. Then I am going to use my Lionel 4660 to power 1/3rd of my grid. Then I am buying another 4660 on ebay to power another 1/3rd. And last, my Atlas power pack will power the last 1/3rd and also my rail. Sounds good eh? I'll post night shots when it's done. Thanks for all your help. I couldn't have done it without you guys.
14. ### InseyMember

Ok I just got everything wired up (still waiting for more lights though). My main power pack is still overloading, but that's because I haven't added the 3rd pack yet. Here's what it looks like so far:

15. ### ezdaysOut AZ way

Yep, looking good now. Ya might have to tone down the light inside that shanty up front, but your lamps seem to be doing will now so keep going.:thumb: