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Jeprachaun
08-23-2007, 01:37 PM
Hello everyone. I do a lot of LED wiring and soldering when modding Xbox 360s. I wrote a tutorial for a modding site on how to wire LEDs a while ago. I figured it might be somewhat helpful here. This tutorial doesn't cover SMDs (surface mount diodes) but I think those would be great when you need LEDs to take up less space. If you like I can write a tutorial on how to solder those. Enjoy!

There are three different wiring methods. These methods are single (for one LED), series (for multiple LEDs) and parallel (for multiple LEDs). I am only going to talk about series and parallel circuits.

SERIES
When wiring in series the voltage of the source is dispersed equally throughout all of the LEDs. In order to find out how much power will be going to each LED you divide the voltage of the source by the number of LEDs. In a hypothetical situation, we have a 12V source and 6 LEDs (each requiring 2V to run off of). Divide the voltage source by the number of LEDs and you will get 2V, which means that 2V will be going to each LED. Great, each LED works perfectly and has the required voltage needed to run.

What happens when you have 3 LEDs (requiring 3.7V to run) and a 12V source? You will have too much power going to each LED. Divide 12V by 3 (LEDs) and you will get 4V going to each LED. Because there will be to much power going to each LED you will most likely smell something burning and will have to go out to buy a new LED. To fix this problem a little thing called a resistor was invented. A resistor is a "circuit component which offers resistance to the flow of electric current. A resistor also has a powerhandling rating measured in watts, which indicates the amount of power which can safely be dissipated as heat by the resistor". In order to figure out what kind of resistor you will need you will need to know several things about the LED and the voltage source:

A) What is the voltage of the power source?
B) How many LEDs will you be wiring?
C) What wiring method will you be using?
D) What is the voltage drop of the LED (How much power does it take to run it)?
E) What is the recommended milliamps (mA)?

Once you know these things you will be able to use a resistor calculator to calculate the resistor that you need (I will go into more detail about this later).

When wiring LEDs together in series you wire from the - leg on one LED to + leg on another (the longer leg on the LED is the + leg). Here is a diagram courtesy of LsDiodes that will clarify what I am trying to say.

http://i22.photobucket.com/albums/b323/liquid-core/Mixed%20Pictures/LEDSeriespicture.jpg

PARALLEL

Now on to a parallel circuit! A parallel circuit allows you freedom when choosing how many LEDs you would like to wire. Many people wire in parallel because of this “freedom”. This kind of circuit works great if you have a small voltage source and need multiple LEDs. If you had a 5V source and wanted to wire 3 LEDs (requiring 2V to run off of) there wouldn’t be enough power to power your LEDs. That’s true with a series circuit, not so with parallel. A parallel circuit works like so: “while every LED receives the same amount of voltage, the current of the source is dispersed between the LEDs.” What this is saying is that you will draw more power from you source. When wiring to a point on the XBOX 360 this won’t be an issue, only if you were getting your power from batteries or a similar power source that couldn’t replenish itself would you possibly need to consider this.

Because parallel doesn’t have any tricks for finding out how many volts is going through each LED I am going to skip to how to wire it. When wiring in parallel you always need a resistor. When wiring in parallel you wire the + legs together and the – legs together. Here is another diagram courtesy of LsDiodes.

http://i22.photobucket.com/albums/b323/liquid-core/Mixed%20Pictures/Parallel.jpg

RESISTOR CALCULATOR

Now that you know about the various wiring methods I am going to talk about resistor calculators. In order to use a resistor calculator you need to know several things (I mentioned these above but here they are again):

A) What is the voltage of the power source?
B) How many LEDs will you be wiring?
C) What wiring method will you be using?
D) What is the voltage drop of the LED (How much power does it take to run it)?
E) What are the recommended milliamps (the desired current)?

Do you know this information? If so lets move on. I am going to be explaining everything from here on, based on this (http://metku.net/index.html?sect=view&n=1&...dcalc/index_eng) particular resistor calculator. Find on the page the wiring method that you will be using (series is in the middle and parallel is towards the bottom). Enter in the information that it asks (that would be my A,B,D,E). Double check the information that you have entered and hit “Click to Calculate”.

The information that you are looking for is this, the “Nearest higher rated 10% resistor” and also “Calculated Resistor Wattage” and “Safe pick is a resistor with power rating of”. When purchasing a resistor I look for a resistor that has an ohmage of the “Nearest higher rated resistor” and a wattage between the “Calculated Resistor Wattage” and the “Safe pick”.

That concludes my tutorial. If you have questions please feel free to ask.

Pictures from http://www.LSDiodes.com
Other reference sites used: http://connectors.tycoelectronics.com/glossary/glossary-r.stm
Resistor Calculator: http://metku.net/index.html?sect=view&n=1&...dcalc/index_eng

O'Malley

Matt Olieman
08-23-2007, 01:42 PM
Excellent info O'Malley :) Thanks a bunch :)

ivar hestnes
08-23-2007, 06:06 PM
This was a very good tutorial.

Lots of neat stuff to learn about.

Thanks:)

Jeprachaun
08-23-2007, 07:58 PM
Glad to you hear you guys like it. Hope it helps out people looking to build a sim.

O'Malley

Westozy
08-24-2007, 04:28 AM
Awesome tute mate and timely too for me, I'm just about to start wiring my overhead panel and radio box. I've completed 3 dimmer circuits design for controlling LEDs.

Cheers, Gwyn

Geremy Britton
08-24-2007, 10:19 AM
Great tutorial,

exactly when i wanted it i've been looking on the internet for something like this and here it is just here :p hope to see other electrical tutorials in the future because i'm by no means an electrical genius! :lol:

Thanks!

Jeprachaun
08-24-2007, 02:00 PM
Great tutorial,

exactly when i wanted it i've been looking on the internet for something like this and here it is just here :p hope to see other electrical tutorials in the future because i'm by no means an electrical genius! :lol:

Thanks!

Neither am I 737 :D. This is a collection of all of my research. Very happy to hear that it will be helpful in the future!

@ Westozy: I've never wired a dimmer circuit before. What components does it consist of? Thanks for the info.

O'Malley

Matt Olieman
08-24-2007, 02:24 PM
Just wanted to add this to O'Malley's wonderful tutorial.

When I wired my panels with LED's I needed to be able to dim them. I asked Mike at www.mikesflightdeck.org (http://www.mikesflightdeck.org) to help me. He designed the following schematic and list of parts needed. Thanks again Mike :)

http://mikesflightdeck.com/led_dimmer.htm

This works absolutely fantastic. Look below at one of my overhead panels.
http://www.a340project.us/gallery/gallery4-11.jpg
You can go here and look at some other pics. http://www.a340project.us/gallery4.htm

Geremy Britton
08-30-2007, 07:25 AM
Hi, unfortunately i dont know if anyone else is having this problem but the resistor calculator won't work any way i want ot connect 11 leds up to a 12v power source in parallel. and each led uses about 1.5v.

I dont know how to work out what type or resistor to use so can you help me. - i think i'v given you all the desired information hope you can help!

Thanks

Geremy Britton
08-30-2007, 07:26 AM
I have been recommended 1K resistors with each led so is this correct?

Gez

Jeprachaun
08-30-2007, 04:26 PM
Hey Gez. Unfortunately the resistor calculator link no longer works. Here (http://diy.sickmods.net/Tutorials/Case_Modding/Resistor_Calculator/) is another great resistor calculator that should help you out.

npbosch
08-31-2007, 01:39 PM
or this one:

http://led.linear1.org/led.wiz

XOrionFE
10-24-2008, 07:42 PM
Just wanted to add this to O'Malley's wonderful tutorial.

When I wired my panels with LED's I needed to be able to dim them. I asked Mike at www.mikesflightdeck.org (http://www.mikesflightdeck.org) to help me. He designed the following schematic and list of parts needed. Thanks again Mike :)

http://mikesflightdeck.com/led_dimmer.htm

This works absolutely fantastic. Look below at one of my overhead panels.
http://www.a340project.us/gallery/gallery4-11.jpg
You can go here and look at some other pics. http://www.a340project.us/gallery4.htm

Matt or anyone that knows.....

I would like to follow this approach but am not an electronics guy. I went to radio shack today and picked up the 7805 and 2N3906 resistor but could not find any resistors that said 82 ohm. I was also confused because they come in different wattages (1/4 or 1/2 watt). in the diagram is the 10K resistor a pot? Some help would be great....

Maybe if someone could take a simple picture of what they did close up. Matt, I looked at yours but it is all too small to make out what is going where. I would like to entertain hooking up to a PC power supply like I have been reading on a lot of the threads here. The LEDs I have are 3.2 v 1500mcd white 5mm.

Thank you.

N242AM
10-24-2008, 08:25 PM
Taking nothing away from your work and for those interested in additional information, here is another reference. Looks like the same pictures in both:

http://www.theledlight.com/ledcircuits.html

XOrionFE
10-24-2008, 08:34 PM
Thanks for sharing but I understand that part. It is the dimmer that I am curious about.

AndyT
10-24-2008, 08:54 PM
A dimmer is a variable resistor that changes how much juice the circuit gets.

Matt Olieman
10-24-2008, 09:08 PM
Here is the schematic for my panel shown by XOrionFE earlier. I used one 150 ohm (1/4 watt) resistor for two LEDs.

Matt Olieman

WJH308
10-24-2008, 09:25 PM
I have been recommended 1K resistors with each led so is this correct?

Gez

Guys, you need to learn Ohms Law to figure out what resistor you need.
I am curious though, WHY do you need a resistor if you wire 3v led's in paralell and the source is also 3v?
I am thinking about making a PWM led driver that dimms and can be controlled through software and external pot.

XOrionFE
10-24-2008, 10:05 PM
Thanks Matt!

That is what I was looking for.

Scott

brianwilliamson
10-25-2008, 02:04 PM
This is the way I do all my Led lighting. First I do not use any resistors, and all the leds are the same voltage rating. I use only high light output leds, which means they are often too bright but then you turn the wick down. here is the basic circuit which will do 3 amps ( about 150 leds at 20 milliamps):
http://i275.photobucket.com/albums/jj281/bwillo_photo/VOLTAGEREGULATOR.jpg
The variable resistor R2 I think from memory is a 1K and I then parallel another 1K variable resistor to use as the Dimmer on my panel. Experiment here with resistance values, as I do not have the exact figures at hand.
The idea is to have the resistors setup before you connect any leds so that the maximum voltage you require is set with the external variable dimmer resistor at maximum, you rotate the internal R2 to set the voltage at maximum voltage that the leds will operate at.( this way you cannot exceed the max. voltage ! ) You need a good Multi meter to set this up.
You will need to use a heat sink on the LM350 which is the one I use instead of the LM150, to get rid of excess heat.
This a cheap and easy way to vary all your back lighting, I use 4 or 5 of these circuits in my Sim.
Regards................Brian W.

jonnydaz53
10-25-2008, 02:21 PM
this what im looking for too . using a atx power supply with the 12v output... if when you get time could you post the spec of the leds and dimmer as i am a beginner . many thanks

john d

brianwilliamson
10-25-2008, 03:10 PM
If you are not too conversant with electronics then perhaps do a search from some of your local electronic suppliers and look for a kit similar to this:
http://www.dse.com.au/cgi-bin/dse.storefront/49036b800d065f96273fc0a87e010648/Product/View/K3592
The circuit is similar to the one I posted and all you have to do is put a variable resistor in place of the fixed one to suit the votage for the leds you have.( that will only give you a fixed max. voltage for the leds) A lot of the new leds are run at up to 4 volts but you need to get the voltage exactly when you purchase them.
Hope this helps, as it takes a bit of learning at first when you start on these projects.
.............Brian W.

XOrionFE
10-29-2008, 08:35 AM
Sorry to sound stupid but I still dont understand something when looking at Matt's schematic.

Is the 10K variable resistor a Pot? Is this just another name for a Pot? Would this be a 10K Audio Taper or Linear Taper if so. I want to duplicate this but am having a rough time and my local radio shack is pretty useless when it comes to asking questions.

Thanks,
Scott

Michael Carter
10-29-2008, 08:58 AM
RadioShack is too busy selling cell phones and satellite systems to worry about basic electronics anymore.

Don't waste your time there unless you already know what you need and where to find it. Most there don't know a resistor from a diode.

WJH308
10-29-2008, 08:59 AM
Sorry to sound stupid but I still dont understand something when looking at Matt's schematic.

Is the 10K variable resistor a Pot? Is this just another name for a Pot? Would this be a 10K Audio Taper or Linear Taper if so. I want to duplicate this but am having a rough time and my local radio shack is pretty useless when it comes to asking questions.

Thanks,
Scott
A pot is short for potentiometer, which is another name for a variable resistor. All your doing is controlling voltage by varying the resistance. Stick with linear pots, otherwise the output will not be linear. Imagine using a joystick with tapered pots, you would pull your hair out or take a sledgehammer to the joystick.

Just another note, a variable resistor, or any circuit that controls voltage via changes in resistance, accomplishes the task by turning the excess energy into heat. Hence the need for a heat sink on the voltage regulator. As far as our needs go in the cockpit, that is fine. If you want to be super nerdy and energy efficient, look into Pulse Width Modulation. Most easily done via a microprocessor. The voltage is regulated by turning the switch on and off at a fast enough rate and changing the duration of the on and off peaks to put out a steady voltage. The excess energy is not turned into heat, rather it is simply not used. Using this method, it would only be a trivial task controlling brightness via software and other methods such as light sensors for an auto setting, or networking the controllers together so you could have a master dial to control all the lights, etc. Basically you can do what ever your imagine dreams of.
However, for all the respect I have for microcontrollers and their uses, the highest form of refinement is simplification, the KISS method.

XOrionFE
11-25-2008, 09:55 PM
Ok

Another dumb question guys.

In Mikes schematic it shows an 18K and 10K resistor with the 10K being a variable resistor. The diagram shows 82 for led resistors (150 if using 3.5 V white or blue leds).

I went to the local electronics store and the resistors I found that were 18 say just 18 Ohm on the package...not 18K. Is this the same?

What about the 82s and 150s? Are they 82K/150K Ohm or just 82 and 150 Ohm?

Is there a diffence or is this all the same?

Thank you
Scott

WJH308
11-25-2008, 10:14 PM
They are most certainly not the same. 15 ohm is not 150,000 ohm.
Mail order via mouser or digi-key, much, much cheaper, buy large quantities in all different values, buy a parts bin at home depot, and well.. Always have what you need when you need it.
About 50 times cheaper that way too!

Ok

Another dumb question guys.

In Mikes schematic it shows an 18K and 10K resistor with the 10K being a variable resistor. The diagram shows 82 for led resistors (150 if using 3.5 V white or blue leds).

I went to the local electronics store and the resistors I found that were 18 say just 18 Ohm on the package...not 18K. Is this the same?

What about the 82s and 150s? Are they 82K/150K Ohm or just 82 and 150 Ohm?

Is there a diffence or is this all the same?

Thank you
Scott

XOrionFE
11-25-2008, 10:17 PM
Crap

That is what I was afraid you were going to say. Well, Mouser here I come.....

So if it just has a number on the schematic it is straight ohms correct?

WJH308
11-25-2008, 10:31 PM
K is for 1000 as you know, and M is for mega or millions. Yes, 15 would simply be 15 ohm. A resistor is nothing more than a coil of wire wound to provide resistance to the flow of electrons. With Ohms law, one can reduce the voltage an LED see's but at the same time also increase the amps. What you taketh away from one, you add to the other. Which brings up another note. Take note of how many watts the resistor is rated for. They come in different sizes, physically.
Oh and before you place your order, make a list, save yourself some money on shipping. Might as well buy a few hundred leds while your at it, and wire, shrink tubing, solder?

Crap

That is what I was afraid you were going to say. Well, Mouser here I come.....

So if it just has a number on the schematic it is straight ohms correct?

XOrionFE
11-25-2008, 10:46 PM
K is for 1000 as you know, and M is for mega or millions. Yes, 15 would simply be 15 ohm. A resistor is nothing more than a coil of wire wound to provide resistance to the flow of electrons. With Ohms law, one can reduce the voltage an LED see's but at the same time also increase the amps. What you taketh away from one, you add to the other. Which brings up another note. Take note of how many watts the resistor is rated for. They come in different sizes, physically.
Oh and before you place your order, make a list, save yourself some money on shipping. Might as well buy a few hundred leds while your at it, and wire, shrink tubing, solder?

Thanks, that clears it up although I was trying to figure out the wattage requirement also. I am trying to do exactly what Matt did using Mike's schematic. And your right, with all the orders I keep placeing for small stuff I could have saved enough on shipping to buy more stuff.

Michael Carter
11-25-2008, 11:53 PM
Near the back of the Mouser catalog they have various kits with many different component values. Even comes in it's own plastic box.

You can get resistors, capacitors, diodes, inductors, etc. It is a lot cheaper that way especially with what Mouser charges for shipping.

XOrionFE
11-26-2008, 12:13 AM
sounds like the way to go

I will take a look at my catalogue

XOrionFE
11-27-2008, 02:56 AM
Finally Finally Finally

I finally figured this thing out and got the right resisters and leds. I used the dimmer to setup 8 7000mcd White 3.2V 5mm LEDs in my glareshield to shine down over the MIP. The LEDs are from radio shack and they give off just the right white color (tinge of blue) to make the MIP look perfect and almost like what I have seen in Learjet photos. The dimmer works great. You can see the dimmer knob on the panel to the left of the yoke. These pictures show min, mid, and max points. Perfect.
Sorry I didnt have the displays turned on for full effect but I kinda had things torn apart.
Thank you to all that helped in this thread!
Scott

AndyT
11-27-2008, 03:23 AM
It looks great Scott! Excellent work!

XOrionFE
11-27-2008, 09:24 AM
Thank you Andy and thanks for your help. The genie is out of the bottle now. Now I can go led crazy!

AndyT
11-27-2008, 01:38 PM