Model Streetlights Help

[nhdesigns]

I'm having some sort of trouble with wiring some OO gauge Streetlamps I purchased on Ebay From SM Model Railways. As good as they look I'm hoping to have them wirired up without any of the LED's blowing. I was given a response from the company that sent me a link to how to guide on wiring multiple lights but it has not made any sense to me. Each of the lights have one bare copper wire and one insulated wire which does not seem to make things any simpler as to what one is positive and which is negative. The information I got in an email about the wiring is :

The only issues with LED lighting is a) They must be connected the correct
way around onto their dc supply and B) you will normally have to wire a
series resistor into one lead (it doesn't matter which lead).
We would recommend you obtain a 12 volt dc regulated power supply to feed
all you lighting requirements. 1.0Amp 12 v regulated PSU can be obtained
fairly cheaply even from ebay. Regulated means the voltage remains constant
regardless of the load (Current) placed on the PSU from 0.001 to its maximum
rating. Therefore your lighting will always receive a constant voltage.
Unlike most other PSU where the volts start high at little current loading
and drop as the current load increases.

LEDs wired in series are connected end to end (the negative electrode of the
first LED connects to the positive electrode of the second LED and the
negative electrode of the second LED connects to the positive electrode of
the third LED and so on and so on...). The main advantage of wiring things
in series is that it distributes the total voltage of the power source
between all of the LEDs. What that means is that if I had a 12V car battery,
I could power 4, 3V LEDs (attaching a resistor to each of them).
Hypothetically this could also work to power 12, 1V LEDs; 6, 2V LEDs; or
even 1 12V LED if such a thing existed.

 

Can anyone help me out on how I go about wiring these up? The ones I got are the same as these ones

[cpman46]

Take one of your lamps and connect the resistor in series with one of the leads. Doesn't matter which one. Using a 9 volt PP3 battery, connect the free leg of the resistor to one side of the battery and the other LED lead to the other battery terminal. If the LED lights up the lead connected to the positive terminal of the battery (it may be the one via the resistor or the other one) is the positive one. If the LED does not light reverse the connections to the battery and it should light up. Using a PP3 battery together with the series resistor will not harm the LED if the polarity is wrong.

Hopes this helps

[cliff park]

Don't forget that the D in LED stands for diode. Providing you limit the current, even a 2K resistor should still work, and the voltage, like Mike says a 9V battery, then you can't do any harm. One way they will light, one way they won't.

[Crosland]

The advice from the supplier is wrong in one respect. When wiring LEDs in series you only need one resistor, not one per LED. The value will be determined from the supply voltage and how many and what colour LEDs you are using.

 

Andrew

[nhdesigns]

The advice from the supplier is wrong in one respect. When wiring LEDs in series you only need one resistor, not one per LED. The value will be determined from the supply voltage and how many and what colour LEDs you are using.

 

Andrew

 

I did think that only one resistor should work for the whole lot. I'm only wiriring up 3 lamps anyway. The instructions on the packet were not much help either. They just showed a wiring diagram that seem complicated to follow. It's a good thing only one resistor is needed as that's all I got left! Apart from ones I already have which are different to the ones supplied.