Several people on these forums ask “How do I wire LEDs?” I decided I would write a brief tutorial so they will understand how to wire and the different methods of wiring. I will also explain the resistor calculator because it seems some people don’t understand how to use it. Let’s begin with the various wiring methods.
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.
If you place an LED backwards nothing bad will happen. The LEDs just won’t turn on. If you need resistor wire this into the circuit before the LEDs. Wire to your power source and a ground to finish up your circuit. Now your circuit is complete and your LEDs will work just fine. I would recommend using electrical tape or shrink tubing to put around your soldering joints to prevent a short.
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.
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 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
LSDiodes.comOther reference sites used:
connectors.tycoelectronics.com/glossary/glossary-r.stmResistor Calculator:
http://metku.net/index.html?sect=view&...dcalc/index_engO’Malley
This post has been edited by G0t M4xx 21: Aug 13 2006, 04:17 AM
How To Wire Leds:, A detailed tutorial.
Jun 18 2006, 09:46 PM
Sorry to everyone that asked, but its true.
