Very Newbie - Basic N Scale Light Wiring question

[Anonymous]

Disclaimer - Honest - I searched Google for about 30 minutes and went through about 4 screens of questions to this forum before asking this. I guess this is so simple nobody else asks. End of Disclaimer / apology.


I bought some n-scale street lights and lighted signs from the hobby store for the n-scale train set I bought on e-bay. Store manager said "hook em up to the AC on the transformer."

That sure as hell did not sound hard. Two wires, two screws marked AC on the transformer. It makes sense. What can go wrong?

In any case, either way I put the wires, the lights will not light, and as long as I have them attached, the train will not run. Perhaps a short? Nothing on the lights package (which I stupidly threw away thinking I wouldn't need it) said AC or DC or voltages or had any wiring diagram... That made me assume this was all standardized years ago.

What is standard? What simple concept am I missing? What question should I have asked, or what answer should the store owner have volunteered? What do people assume I already know? I apologize for this.

Thank you in advance.
Fowler

[Anonymous]

couple of questions back to you:

What gauge wire are you using to connect both the lights and the track power? if it's too thin (a high AWG number), then the wire's own internal resistance may be dropping the voltage too low for the lights or for the track to run. I'm not saying that's your problem, but it is something to check first.

Second question: How did you wire the lights to the AC terminals on your transformer? If you hooked them up in series (one wire to the next wire) in a daisy-chain, it's possible that the total impedance (same as resistance) of all of the lights is too great. My recommendation would be to use at least 14 gauge wire, one for the "A" side and one for the "B" side of a ladder. Then, wire each light to those wires so that the light makes a "rung" in the ladder. It's not a physical shape, but an electrical shape I mean. Anyway, once you have that done, then connect the two 14 gauge wires to the AC terminals and see if that makes any difference. A benefit of wiring it this way is that if one light is bad, it won't affect the operation of the other lights. (Remember the OLD Christmas lights?) Another benefit is that as you add lights, total impedance of the circuit decreases (one of those weird electrical phenomena). That's why electricians tell you not to put too many fixtures on one electrical circuit - as impedance decreases, current increases and with an increase in current, a bit more heat is generated. For what you are planning on using, this isn't too much of a concern, since each "rung" of the ladder will be subjected to a fraction of the total current. If one rung burns out, the impedance increases, and the total current decreases. Wow! Sorry, got kind of carried away.

In summary: Large diameter (small AWG number, at least 14) bus wires running the length of your layout. Strip insulation off each wire and solder the feeder wires from each light to those "bus" wires. Parallel wiring will help keep the currents low and risk of fire low, as well as allowing you to pinpoint the bad lights in the circuit.

[Anonymous]

If your lights are LEDs, the rules are a bit different than normal lights. An LED (Light Emiting Diode) is a diode, and therefore will only let current pass in one direction. With DC, this is not a problem, assuming you hook the negative side to negative, and same for positive. With AC current, the voltage cycles in a sine wave, going from negative to positive about 60 cycles every second. If you hook an LED up to AC it will probably get hot, because it is essentially cutting off half the power (the negative voltage) and this creates heat, the amount depending on the current.

In summary, make sure if you have LEDs or not. Don't hook an LED up to AC, and make sure it is rated for the DC voltage. And do what joekc6nlx said and hook up the lights in parallel (the ladder way), not series (in a line).

[Anonymous]

joekc6nlx,

AWESOME reply. Very visual. That was one of the best descriptions of parallel vs. series I have ever read.

[e-mail],

Great advice to you... I suspect something else is happening though. Test your AC power source with a multi meter. Does it put out all 16V AC?

Light bulbs can typically run AC or DC. They do not have a specific direction of current like LED's or like motors.

HOWEVER, in our little N Scale world, a lot of the light bulbs are sold as either 12 - 16V AC or DC. OR they come as 1.5 Volt bulbs. (If your power supply was working, and they were wired as Parallel (rungs in the ladder,) and if they were 1.5 volt bulbs, then you popped them in the first nanosecond you turned on your power.)

Personally, I wire one bulb out of any unknown pack to the variable DC of my controller, I then start with the knob at ZERO, turn on the power, and "test" the bulb by turning the power "UP" until it either blows or I reach MAX (12 - 16V DC.)

Otherwise, try to always verify the bulb rating when you purchase them.

[Anonymous]

I will check with the voltage with a meter and the DC idea is great.

The lights are simply lights from "Model Power" No 1329 6PCS Hand Painted.

At a minimum, I realize from the replies above that I may be in a troubleshooting situation as opposed to a "doing it the wrong way" situation.

To answer questions about the wires and guage, I simply hooked the lights from the package directly to the AC. There is a little yellow and a little brown wire that come out of the Exxon sign (for instance) and I just put those wires to the AC to test the light. At that point in time, the light would not come on, and the DC also would not work.

Thank you,
Paul Fowler

[Anonymous]

We will stay with you, just keep us informed. Good luck.

[Anonymous]

It appears I can close this thread... with the Thank You's (especially for the parallel vs series) and for all the contributors.

This morning I tried out the circuit with exactly the same hardware and the lights lit up....

I do not get it - why it didn't work yesterday - but it is working today. Perhaps a short I was unaware of (although it seems unlikely given that I kept trying different lights directly to the transformer, so one would think the changing of hardware would remove any short...) but who knows???

In any case, guess where I put the little layout? My office at work, and it is looking better each day.

Thank you all,
Paul Fowler

[Anonymous]

You are truly lucky that you get to have your layout at work. They won't let me carry mine around at school.