Picture of Ultimate guide to LEDs
Hi. I am Dog digger.
I will be showing you the ins and outs and all the details about LEDs. This has taken me a long time to make.

LEDs. They are awesome! They are essential to life today. They are used everywhere and you can get them almost everywhere. You can do so many things with them and I will show you the types and what you can do with them, some projects and more!

Don't forget to comment and vote in the LED contest!
please don't be too critical, I'm only 13 years old
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Step 1: History

Picture of History

The technology of LEDs started with electroluminescents. This was experamented in 1907 by a experamenter by the name of H.J Round in Marconi Labs in England. He experamented with a single peice of the element, silicon (which i will explain later) and a cat's whisker detector which consisted of a thin peice of wire that connected to the anode and the base of the semiconductor connected to a cathode. A voltage was applied and light was produced in the form of electro luminescence. however the LED was not fully introduced. The idea was abandoned. In 1961, the first real LED was born. Two Texas instrument experimenters made the first infra-red light produced by a single piece of Gallium arsenide. This is a material that consisted of gallium and arsenic. They received a patent for the LED and they were introduced to the world. The first visible spectrum LED was made in 1962 by Nick Holonyak Jr in GE electronics. Back then LEDs were horribly expensive costing $200 a unit. That was... until 1968. A company by the name of the Monsanto Company first mass-produced these red LED indicators using the Gallium Arsenic that was used before. In that same year, HP also mass produced LEDs with the GaAs (gallium arsenic) that Monsanto supplied them with. Hp used them in their calculators instead of LCD screens. In 1970 Fairchild Optoelectronics ( with the help of Fairchild semiconductor) manufactured the LED for only 5 cents! Using the planar process invented by Dr. Jean Hoerni at Fairchild Semiconductor and innovative packaging, optoelectronics pioneer Thomas Brandt led the team at Fairchild semiconductor and they were successfully producing LEDs for low prices. Later on down the track, companies use different materials other than GaAs and produced different colours. The first High Output blue LED was created by Shuji Nakamura of Nichia Corporation in 1993. He used a combination of different materials to create this LED. Later, the high brightness White LED was made by this same man and he received many awards. Today, you can get almost and LED to suit your needs. LEDs are truly awesome!!

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Hi There, just wanted to give a thumbs to this guide, very informative with a good flow and format. Thank you for your work

Nice Instructable.

Another Awesome instructable about LED's

callen4611 months ago

nice work. You have just taught a forty six year old loads thank you

Darwesh Murad11 months ago

This guide rocks!!!!!!!!!!!!!!

robaboudi1 year ago
Great 1st step in learning about LED's!
Wow, you are amazing. I hope to be able to do what you've done here someday.
I am hoping to get some LEDs but I'm not sure where to get them cheaply from. Where did you get yours from?
I get mine from but you could find them almost anywhere
gmehta11 year ago
Happy to get proper great knowledge thanks
Warmtint2 years ago
Great tutorial DD!!

I need things kept simple and you did just that. I am so impressed with yur comfortable knowledge of this stuff at your age and its impressive how you have the patience to want to pass on your knowledge. I think you have a bright future and keep making instructables!!
dog digger (author)  Warmtint1 year ago
Thanks! (Sorry for late reply)
Dr11 year ago
Hi mate, great work.
I need some help, I was thinking of linking this to an LM386 amp to amplifier the signal. This would be to allow the lights to be more responsive when the sound is lower. Do you think this would work, also any idea how to do it????
dog digger (author)  Dr11 year ago
Yes It's possible (sorry for the late reply). There are some very simple LM386 amp circuits on the internet but there are so many different amps and amp types you could use. An LM386 would be overkill but it would work
Zakaria.K1 year ago
Btw tri-leds also have a type of them called RGB led...
hsarode12 years ago
I did everything that was written in the sun leds to music and soon my wire that goes to emitter came out and I was too bored to solder the wire again sp I just again simply hooked in the audio jack and to my surprise the led was blinking according to music. I dont know why. The led was blinking even when there was no wire connected to the emitter
agm882 years ago
question im making an amp and trying to put this LED synce in the curcut but cant figure out a place to put it any ideas
dog digger (author)  agm882 years ago
Try in the input section before it gets amplified. Sorry for the late reply
atineo2 years ago
Thanks, i got allot of useful info
This is great! I work at the shack and see a lot of students with LED projects that I have helped over the past 2 years and I can't tell you how many I have referred to this site. Let alone the countless number of students I have helped to wire and configure their projects right inside my store. I will keep this on hand as handouts. A lot of these students are completely lost on wiring one led let alone several!! It is rewarding when they bring in their final projects to show me though.

One thing I have done and seen done to get the light to disperse more from an LED is one use fine sandpaper and flatten the rounded tops.
Wow, I'm impressed that someone at the Shack knows anything about electronics! In the few times I can't wait for a part to come in the mail from one of my distributors and have to buy it in the store, the employees usually just point towards the cabinets and walk away slowly when they ask what I need and I say "parts." They still always try to sell me a cell phone and batteries though.
astroboy9073 years ago
Hey Dog Digger- just took a look at this project, imma get some LED's, what do you think I should do w/ them? I was thinking a 24x6 led matrix and maybe some audio blinkies...
dog digger (author)  astroboy9073 years ago
You could make an arduino controlled 3D audio analyser! It would be awesome
well I am planning on making a 4x4x4 cube :)
Update on cube- got the led jig ready, just have to sand down my leds, spend forever soldering, hook to board, program microcontroller, get audio ready, and lots of other stuff :) but its coming along :)
yikes! hit a problem. 4x4 led grid = 16 LED outputs. 4 layers = 4 more outputs...
And the arduino has only 20 usable pins :\ no audio input unless I go all shift-register-y on it.... Hmmm :-\
Oh and member Robot Lover is having an advent calendar type thing- you just have to publish a christmas related ible on a day before Christmas in december. Shoot him a PM if you want more info, tell him astroboy907 sent you :)
Are you talking about a 3D 4x4x4 cube, or just a 2D 4x4 square? In either case, the simple answer is to multiplex the LEDs. No shift registers are needed. There are lots of online resources for doing this. Basically, the LEDs share control lines in a pattern so that a specific combination of control signals will turn on a specific LED. It is all about how they are wired together and how you program the controller!
siamonsez3 years ago
You really seem to know what you are talking about, nicely explained for the laymen.
I am doing a flashlight conversion and was wondering if you could tell me if what I am thinking is correct.
My plan: 4.5v power source (3x "D" batteries)
> switch
> 9x LEDs in parallel (3-3.2v @ 20mA)
> 3x resistors in series (200 ohms each)

All the ibles I have seen use one resistor per LED and have the LED/ resistor pairs wired in parallel, but it seems to me that if the LEDs are all the same then a sub-circuit(?) of resistors in series can be used to add up to the required resistance. Am I on the right track?
What you're thinking can work, but it is not typically good design practice. Also, I think you are misunderstanding how this would work. See the attached image to see what I am saying.

If I understand what you have said, you are putting 9 parallel LEDs in series with 3 series resistors. Putting resistors in series increases the total resistance. If the LEDs are consuming 3V and the source is 4.5V, then there is 1.5 V across the total resistance (which is 3*200Ω = 600Ω), hence the total current is 1.5V / 600 = 2.5mA. This current is split up among the LEDs. Since they are not all perfectly identical, they will not all consume the same current, but the average current through each LED would be 2.5mA / 9 LEDs = 0.278mA per LED.

To get 20mA per LED, you would want a total current of 9*20mA = 180mA. To use a single resistor to limit the entire LED bank, you would want 1.5V / 180mA = 8.33Ω total. This resistor would need to be rated for 1/2 Watt of power (1.5V 2 / 8.33Ω) * 2 for safety... 

The problem with doing this is that the LEDs are not all identical. It is likely that one will use more current than the others and be brighter. When one LED burns out (and one eventually will) then the total current (180mA) is now split among 8 LEDs instead of 9. This slightly raises the average the current per LED, but due to the imperfections in LEDs, will probably cause another LED to hog the power and burn out, splitting the total current among only 7 LEDs. Of course, this is given ideal conditions. In actuality, the voltage drop and/or current draw will vary with each and every LED.

The best solution is to use a single resistor per LED string. Then you would want to use 1.5V / 20mA = 75Ω per LED. By the way, dividing the individual LED resistance of 75Ω by the number of LEDs (9) is a shortcut to find the necessary total resistance of 8.33Ω if you still wanted to do your original idea.
LED Tutorial 1.jpg
dog digger (author)  siamonsez3 years ago
It's best to use a 75ohm resistor for each LED. It's the best way to do it. I've had projects that use 4 LEDs per resistor that suits the current of 4 LEDs in parallel and within a month, most LEDs had burnt out and if one LED burns out this way, the others burn out if the LED's voltage drop decreases.
weaverowns2 years ago
hi just wondering if it is possible to use el wire instead of an led as i think it would look cool going round my speaker and great instructable as well thanks
You could, but it would need its own control circuitry. EL wire requires a higher voltage and an alternating current to function. It can still be battery powered, it just needs a control circuit to create AC power from the DC source.
Tex632 years ago
Great Information ,

I was wondering how would i make a strobe light bar with 46 LEDs and what would i need?
any informationwould help!

Look into this chip: 555 Timer IC. With this chip, you can manually control the speed of the output pulse with a potentiometer to create a variable speed strobe light. If you use the output of the chip to turn on a transistor like a switch (I suggest a "logic level MOSFET") then you can rapidly blink a lot of LEDs...

For a 5 V output, I would make 23 parallel strings, each containing two series LEDs and a current limiting resistor. In any given string, the current through each LED is the exact same. The total current would be 23 x the current of a single string. The transistor would need to be able to switch at least this much current - I would double it for safety.
h2ofarmer2 years ago
Great job ... Thank you for your help!
lithelady2 years ago
I'm a 73 year old Granny, still learning new things to keep up with all the brilliant 13 year old kids like you. THANKS for making a basic tutorial...Now, I'm going to order a few supplies and start experimenting....
Thanks. I learned a ton. Your method of calculating resistor ohms was very clear and helpful.
mpratt12 years ago
Would a 2N3904FS-ND transistor work with two AA's and any random LED's i happen to have lying around?

Also, where would you recommend a switch be put in the circuit if one were to be installed?
dog digger (author)  mpratt12 years ago
The 2N3904 will work and the switch should be put in between the positive of the battery and the LED
schumley2 years ago
Good stuff, super impressed, you'll go far!
lilwitteck2 years ago
hi great instructable :D do you know how long they stay lit after they are attached?
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