LED Lighting 101?

[Flounder]

I remember a post that explains how to wire LED lights for scenery in the old forum. I searched on the old forum but could not find it. Does anyone have a link, or a copy of the thread that they could post?
Much appreciated.

[jaws]

You may look in "Layout and Planning" on the current board. There is a message about "Stadium lights" that may be helpful.

Jim

[lance]

LED lights have a current limit they can take before they blow out. Decide on what voltage you are using for them and choose a resistor to limit the current. Most color LEDs are around are .020 amps. Blue and white are different.
you could look for LEDS with the resistor installed with wire leads on the ebay.

[LegOutOfBed]

WIRING LEDs
LED stands for Light Emitting Diode – in case you didn’t know, and they are a very efficient form of lighting, as there is virtually no heat generated.
So almost all the power consumed is converted to light.
This also means you can use what seems like a very small (and cheap) power supply to power lots of LEDs.
LEDs use low voltage, so they are safe to work with. The only real danger is of shorting something out which damages your power supply or causes a fire.
Mainly because they are not getting hot, LEDs have a very long lifespan. You may never need to replace any LED lights you have set up.
One point I should stress is that the power supply should be “regulated” – that means the output voltage does not change when the current load changes.
Most small, modern power supplies are regulated, but some older ones aren’t.
Some LEDs such as colour changing LEDs, flashing LEDs and 5V LEDs are designed to run off a 5V supply and therefore don't need a resistor.
All other standard and bright LEDs will need a current limit resistor.
If you are buying some made up items such as miniature street lighting, a commercial supplier will generally state one of:
- Has an integral resistor wired into the unit, and is ready for use with a DC power supply of xx volts
- Comes with xxx ohm resistors suitable for xx volts DC supply – you fit the resistors yourself - or a resistor of a different value if your power supply has a difference DC output voltage.
- If it says nothing – check. You may need to buy some resistors yourself.

If you are buying raw LEDs, you usually need to buy your own resistors.
LEDs have a positive and a negative terminal, also known as the anode
and cathode. The cathode should be connected towards the ground or
negative side of the power supply, and the anode toward the positive
side. The longer leg of the LED is the positive side.
Another way to tell which is the negative side of your LED is to look for
the small “flat” on the base of the LED head. This is always on the
negative side of the LED



The resistors can be connected to either terminal of the LED.
I strongly recommend you wire the LEDs in parallel like in the diagram below; using one resistor for each LED.


How do I know what value to resistor to use
Firstly you need to know the operating voltage of your LED, which is very typically 1.2 volts DC, although some are up to 3.7 volts.
Secondly, you need to know the current draw which the manufacturer says is the safe amount to push through your LED.
A very common value is 20ma (milliamps) which is a tiny amount. Super modern super LEDS can use a lot more.
Both values should be stated in the sales information for the LEDs.
You can use this formula to calculate your resistor value.
" Power Supply Voltage (V) minus Led voltage (Vled) divided by LED current (Iled) "
(also shown as R = Vled / Iled )
- Or you can use a simple spreadsheet which will calculate it for you.
Here is a web link to my calculator
As resistors come in certain standard values, simply choose the nearest resistor value larger than the number calculated.
For instance: For 1.2v 20ma LEDs with a 6 volt supply as in the previous diagram, the resistors calculate to 240 ohm, so you would use 270 ohm ones.
This is to ensure that you do not allow too much current to flow through the LED and eventually cause it to fail.
The smallest current capacity of resistors which is commonly sold is “1/8^th watt”
Trust me, this is plenty and more than you need. But if you have, see for sale some cheap ¼ or ½ watt resistors, you can use those equally well.
It will make absolutely no difference to the LEDs or the circuit what current capacity resistors you actually use.

But what if some of the LEDs are of different value voltage or current?
– Simply calculate the formula for each value of LED separately, and use the different value resistors applicable to each type of LED.
They can all be used alongside each other in the circuit diagram above. – Again, it will not cause any difficulty for the circuit.

How big should my power supply be? – Simply add together the current drawn by each LED.
In the example above it would be 20ma + 20ma + 20ma + 20ma = 80ma (milliamps)
- The smallest cell phone charger can probably put out at least double this amount…..

How do I put a switch in the circuit – That’s dead easy, see below



That should be sufficient to get the average beginner working happily with wiring LED circuits

If you would like a PDF copy of this article, you can download it at this link

[Flounder]

Thanks for all of the great information!!

[RichD]

Here is an article that I posted several years ago: https://drive.google.com/file/d/0BzL...ew?usp=sharing
Articles found on the Internet can disappear, so if you have found something that might be useful in the future you might want to save it on your own computer.

[rolo9th]

Thanks for that, interesting article.

I think I understand the basic premise for the LED Strip lights...solder a resistor into the incoming positive wire...my question is, how do you string multiple lighted areas together? For example if I had a pit lane with say 6 pit buildings, and each one I wanted t have a light in, how do I daisy chain all the lights together, or do I? And what does the light assembly (wire/resistor/light bulb) tap in to? Is there a junction box or buss that they all connect to?

I want to give this a try, but I am so worried about playing with electricity...and my track history with DIYS-projects is not an enviable one.

[slothead]

Just had a thought. Now that they will be dirt cheap with Christmas behind us, what about getting an LED string of Christmas lights and using that as a starting point? Maybe run the string along the back of the pit buildings and insert one or more lights through small holes into each individual building. I know you can get different size LEDs and sets with white or colored lights - we have them on our tree.

[LegOutOfBed]

.....I think I understand the basic premise for the LED Strip lights...solder a resistor into the incoming positive wire...my question is, how do you string multiple lighted areas together? For example if I had a pit lane with say 6 pit buildings, and each one I wanted t have a light in, how do I daisy chain all the lights together, or do I? And what does the light assembly (wire/resistor/light bulb) tap in to? Is there a junction box or buss that they all connect to?

I want to give this a try, but I am so worried about playing with electricity...and my track history with DIYS-projects is not an enviable one.

I actually explained that Rolo - they all go in parallel. - "Daisy chain" may mean different things to different people, so I don't use that term - stick to the diagram - keep everything in parallel - just keep running the + and - wires and adding more lights to each building.
There is no need for a bus or anything complicated, just twist wires together or solder them as required. What I have draw is essentially all you need.

Slothead - The problem with Christmas lights are multiple
- the spacing of the lights is never going to be exactly as needed
- They will end up being much too bright for what you want around your track - especially with room lights off
- You cannot add lights of preferred colours to different areas, eg warm white versus cool white versus blue or other.
- You cannot add "weaker" lights using a different LED, or by using a larger value resistor to make that particular light more realistic/less strong etc.

With a little effort and patience, nasty word that, patience, you can achieve some good effects.
You can see different coloured light effects in the pits etc.
I have actually just replaced half the lights and done more scenery, but haven't done a new vid. This one i s a few years old
[YTB]UCskERTSHWo[/YTB]

Some more recent pics









This is how I pre-wired the underside of my track. - might help

Main console panel components pre-wired, and 13 LED lighting circuits for track lighting, plus the timing bridge. Just need a few more cable clips to tidy up the LED wiring. Everything needs clipping in place so it doesn't hang down, as the underside of the track will be crammed full of 'stuff".

[RichD]

My oval track has a total of 22 light poles, each with two LEDs in series. Under the table there are two loops of bare 14 gauge copper wire connected to a variable power supply set at 7 volts, so no resistors are needed. The ends of the wires from each light pole are simply wrapped around the loops, four of the light poles have to be removed if I want to convert the track to a road course. 7 volts is not very dangerous and in any case there are never any pets or children around my place that might get a shock. I could have wired the lights on each pole in parallel and set the power supply at 3.5 volts. I store things under the table so nobody is likely to crawl under it in any case.
If I wanted to add lighted buildings I could arrange the LEDs in series pairs and then have as many pairs in parallel to have a single drop for the entire building. If I needed an odd LED that could use a dropping resistor. LEDs are available with different light output ratings, I needed enough output to light the track for night racing, but for buildings lower output LEDs might be better, but they would all run on the same voltage.