Working With Leds



Leds and resistors are very easy to work with, once you learn how they work.


  

Leds:

A led is a light emitting diode, which means it lights up when proper current is supplied in the right direction. They have a positive side, and a negative side, meaning one side always has to be hooked up to the juice, and one side goes to ground. If you look at the two pics above, you can see that inside the leds, the left side has a small wire and the right side has a larger clump of metal. The small wire is always the positive side, which is called the Anode. The larger clump of metal is always the ground, called the Cathode.




Resistors:

A resistor is a small component that lowers the amount of electricity in a circuit. The theory is, if a led requires a low voltage, but you have a higher voltage, if you put a resistor in the line it lowers the voltage to the proper amount so the led doesn\'t blow (not explosivly, more like a light bulb dying). All resistors are bi-directional, meaning it doesn\'t matter which end goes first. Resistors come in many different values, called OHMS, each lowers a different amount of voltage. A resistor\'s ohms value can be determined by reading it\'s color codes, or it can be measured with a meter.

Here are some sites that explain resistor color codes:




Making a single led circuit:

A basic led circuit will look just like the diagram above. It begins with a positive voltage source, the current goes through the resistor, and then to the anode of the led. It comes out the cathode, and goes to any ground.

An xbox has several easy sources of positive voltage: An xbox has many connections to ground:





Making a series led circuit:

A circuit with the leds in series looks like the diagram above. The current passes through the first led, then out to the next. You can chain as many leds as you want in series, as long as there is sufficient voltage.







Making a parallell led circuit:

A circuit with the leds in parallell looks like the diagram above. The current is shared among the leds equally, and each completes it\'s own small circuit. Because of this, if one led burns out, the rest will stay lit. Connecting leds in parallell is very useful because you can hook more leds to a fairly low voltage this way.



Determining your correct resistance:

There are a number of resistance calculators available on the web, but first you need to know some basics of electricity.

Voltage: This is the electric potential difference between any point and a ground. Voltage is measured in VOLTS.

Current: This is how fast the voltage travels through the circuit. This is measured in AMPS.

Resistance: This is how much a resistor can lower the voltage in a circuit, and is measured in OHMS.

LED Forward Voltage: This is how much voltage a led should be supplied with to work properly. This info should be supplied with any led you buy. (usually 3.3v)

LED Forward Current: This is how much current your led should be supplied with. This info should be supplied with the led also. (usually around 20mA)



You should determine your source of voltage, and how many leds you plan to connect, then check out one of the led calculators below:



If you just want the short answer to which resistor to use, here are some very common uses pre-calculated:
These values will work fine for most leds. While a calculator will give you the exact resistance, leds are fairly flexible about it, and anything fairly close will work fine. Now you're ready to hook up a led circuit of your own!


aweirdguy