The Complete Guide to Using LEDs





Introduction: The Complete Guide to Using LEDs

About: I make a lot of things and add my own twists to everyday objects. I would rather make something on my own than buy it. ofton times I save money that way!

LEDs con be confusing sometimes so I decided to make a guide on using them. If you have any Questions about LEDs that werent answered in this instructable, Please feel free to comment or question.

Step 1: Power Intake

LEDs are wiered about there power intake. Most LEDs require about 3 volts any more, and they burn out and smell bad. any less, and they dont light up good. I know what you are thinking you can use a 1.5v battery such as a AA or AAA if you have a Joule Theif, but that is another instructable. As of amperage, LEDs very greatly across a wide spectrum of highs and lows, but 20mA is standard.

Step 2: Annode or Cathode?

Another thing LEDs are wierd about is their positive (+) and negitive (-) legs. LED stands for Light Emitting Diode. Since a diode makes power go one way, It has to be on the right way for it to work. there are a few tricks to finding what is the annode (+) and what is the cathode (-).
ne is that the Cathode is shorter than the annode. the other is that the side with the cathode has a flat spot on it. Using these tricks will help you not mess up you LED related circut.

Step 3: Many Colors

LEDs cme in many sizes shapes and colors. this makes them extremely versitile. ther are alot of exotic LED colors but here are alot of the standard ones.
There are also:
Blinking LEDs
A lot more

Step 4: Connections

There are 2 ways to wire LEDs together. One is to wire them Annode to Annode   Cathode to Cathode that will run on the same voltage but more amperage. the other is to wire them annode to cathode annode to cathode. That will have a higher Voltage but a lower amperage.

Step 5: Update: Resistors.

Due to popular community request, I have added a section about resistors and ohm's law.
First, resistors. Resistors are small electronic devices that limit current and/or voltage. (hence the name resistor) In "power sorce" I put a big, fat X over the 9v battery. That was wrong-ish. You can use a 9v IF and only if you have a resistor. "But what resistor should I use?" is a qestion I can hear through you computers. You have to use "Ohm's Law". Ohm's Law is a mathematical formula used to find resistence, voltage, or amperage. (it can also determen wattage, but that is a little complicated.) It states: R=V/A where "R" is resistance, "V" is voltage, and "A" is amerage. Using that, you will be able to find the proper resistor to use with you LED. (You have to do the math on your own, that way you learn) 

Step 6: End

hope this helped you enter the wonderful world of LED projects. I am open to any and all comments and/or requests. I'm not promising that I will put it up, but I am open to you ideas.

                                                                                                 - Techturtle2



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    Thank You the approximate Current & Voltage values are helpful.

    Thank you! The resistor stuff is just what I was looking for. Now I am brave enough to actually try it.

    can u tell how to light led using AC.
    Do i have to use diode.
    i used 100k resistance for a 230v AC supply, red led worked properly but white led stopped working after 5 seconds and was damaged.Can u tell me why.PLZ

    your explanations are really easy to follow thanks. i have no electrical background, voltage im guessing is the power of something what is amperage?

    1 reply

    Amprage is how fast the electrons are moving, Voltage mesures how far from ground the positive is:
    5v= +lead-----------<5 volts>---------------ground (0)

    Right..., so, taking your "R=V/A" to the circular chart, the resistance can be found by dividing I (volts) by E (amps), dividing P (watts) by the square of I (amps), OR dividing the square of E (volts) by P (watts)..?

    And the same principal (ie, the central value can be found by ANY of the 3 methods shown) applies to the other segments?

    So, if I know the voltage (E) of my power supply and the amps (I) of my LED/LED's, I divide the first by the second to find the necessary resistance..? And I assume that if there's no exact match available, I'd be best using the nearest HIGHER resistance?

    But, just a minute. LED's are measured in MILLIamps - does that mean I have to divide/multiply the result of my calculations by 1,000? And how would I know which?

    1 reply

    if you had a 9v power supply and a 30mA LED, you would divide as follows:

    Oops i frogot the arrow thingies.

    Not at all resistors cost pennies - You should still nclude a resistor no matter what the power source to allow for changing battery voltages.

    1 reply

    I use Metal oxide film instead od carbon film. they are more accurate and thus more expincive.

    There isn't any reason not to use the 9 volt battery as long as a suitable resistor is put in series with the LED to limit the current drawn.

    2 replies

    That is true but you need a strong resister which will probably cost alot of money.

    You are also at a disadvantage with the mAh of the button cell which can be rather small compared to a PP3 or a AA cell. A single LED on a 9v supply would generally require around a 300 ohm resistor which costs me around half a penny per resistor for a 270 Carbon film 1/4W resistor. This page really needs to explain about resistors and their usage aswell. Rory

    Well, because this is the introduction to the prologue of the first chapter of the first delivery, not bad! We'll see how it continues...

    This needs work doing on it (e.g. spelling), and some more information that gets you towards "complete".