LEDs for Beginners

This instructable shows how to wire up one or more LEDs in a in a basic and clear way. Never done any work before with LEDs and don't know how to use them? Its ok, neither have I.

***If you have wired up LEDs before, this explanation might seem overly simplistic. Consider yourself warned.***
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Step 1: Get some LEDs

So I wasn't completely honest - I have used LEDs once or twice before for simple applications, but I never really knew what I was doing, and since so many projects on instructables use LEDs, I thought I might as well teach myself and post about it too.

I know that there are many projects already posted that contain information about how to wire LEDs for simple projects - LED Throwies, LED Beginner Project: Part 2 and 9v LED flashlight - teh best evarrr!, but I think that there could still be some use for a detailed step by step explanation about the basics of LEDs for anyone who could use it.

The first step was to buy some supplies and figure out what I would need to experiment with. For this project I ended up going to Radioshack because its close and a lot of people have access to it - but be warned their prices are really high for this kind of stuff and there are all kinds of low cost places to buy LEDs online.

To light up an LED you need at the very minimum the LED itself and a power supply. From what I have read from other LED instructables wiring in a resistor is almost always a good idea.

If you want to learn about what these materials are check out these wikipedia entries:
Power supply


LEDs - I basically just reached into the drawer at Radioshack and pulled out anything that wasn't more than $1 or $2 per LED. I got:

2760307 5mm Red LED 1.7 V
2760351 5MM Yellow LED 2.1 V
2760036 Flasher Red LED 5 V
2760041 2 Pack Red LED 2.6 V
2760086 Jumbo Red LED 2.4V

Power Supply - I really didn't know what I would need to power them so I bought some 9V batteries and some 1.5V AA's. I figured that would allow me to mix and match and make enough different voltage combinations to make something light up - or at least burn those little suckers out in a puff of smelly plastic smoke.

Resistors - Again, I wasn't too sure what I would need in terms of resistors here either. Since I got a whole bunch of different LEDs with various voltages I knew that I would need a couple different types of resistors, so I just bought a variety pack of 1/2 Watt Carbon Film Resistors (2710306).

I gathered up a soldering gun, solder, needle nose pliers, electrical pliers, some primary wire and electrical tape too since I thought they might be useful.

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sushil0101 month ago

actually i already got 5 led(white) in series with 4.5 power supply..and there is one resistor well i dont care about that resistor. Now the main problem is supplying 4.5v to it is really difficult for me i need to buy batteries time n again,instead of that 4.5v i would like to replace with 12 volt(lead acid)battery just to supply power,for that what resistor do i need to replace with?please help me.

ttompson1 month ago

I want to get LED lights for my car. I think they would make the road trips brighter. It'd be nice for all that night driving.

Tara |

djspincycle2 months ago

Hi Noah, Some LED spec sheets list "Foward Voltage" and "Reverse Voltage". Which is the voltage that is correct for supplying to the LED?

Forward Voltage is the volatage when it lights up. reverse voltage is the limit to what it can take hooked up backwards. Hint: If you want to hook an LED to AC, make sure that the forward and reverse are both 1.4X the rated AC voltage. For example, if you wnat to hook up a series of 3V leds to make christmas lights and run them off 120VAC, you could use 56 lights, or 50 lights and a resistor.

thinders2 months ago

i followed the steps in this project ....

and posted a comment (with a pic) that my LEDs have all gone "dim" ....

Can someone take a peek at what I posted and advise me on what I did wrong ...thanks

eortega85 months ago

"What that means is that if I had a 12V car battery, I could power 4, 3V LEDs (attaching a resistor to each of them)." Can someone please explain why he needs to attach a resistor to each LED if all together, the LEDS use up the 12 volts?

Leds work differently than incandescent lamps. first it is a semi conductor, when the voltage is applied, current rushes through the Led as if there was no resistance. incandescent bulbs increase in resistance as they warm up if I remember correctly. more current equals more power and consequently more heat. thermal runaway kills semiconductors.

dudes eortega84 months ago
Because the amps of a car battery would blow out an led instantly. It's not all about volts it's also about amps. Hope this helped.
his_bevness3 months ago

Brilliant Instructable thanks, from a grateful noob!

djmaxpaul3 months ago

I dont see why ppl complain about Series LEDs. I was 12 years old when I took apart Boom Box I had. I made about 9 holes in plastic with solder gun. Connected LEDs in Series. Plus LED Solder to Plus on speaker and last LED Cathode to Mines to Speaker. More volume more LEDs flashing showing how music is loud and worked as UV Meter. Not that big deal with Series LEDs. I didnt even used Resistors. Looked cool.

chuchomalaga3 months ago

thanks a lot for your explanation, may I use it in my classroom? Easier you explain, easier you understand. And best of all, think with the hands.

thanks, its very funny and easy

paci635 months ago

any thing new

paci636 months ago

thank u so much it was very very helpfull for from all sides

bradix146 months ago
noahw, thanks for the great explanation of the basics!
jdeth9 months ago
Well, this should say how to get lucky because you're using small power supplies and incorrect math to calculate current and voltage division.
Throw a meter on that circuit.
Your LED's are seeing about 45% of the voltage each, the resistor less than 10%.
The theory of operation for semiconductors is based on charge carrier theory.

I'm glad I stopped relying on internet "experts" to help out us beginners and finally went to college to become an electronic engineer a few years ago.

This is very rudimentary and bad science folks!
bradix14 jdeth6 months ago
jdeth, will you please clarify what the good science is and what we beginners should know differently than presented above before we go use this to do projects?
If the battery is 1.5 volts and the led has a voltage drop of 1.7 volts, then how is it lighting? Am I unaware of something?
1.7 is probably max.
JCA1009 months ago
What a Brilliant Tutorial. I have only just discovered Instructables and this is just what my RMT students need for their GCSE Lighting project. Thanks for all your hard work. We will make good use of it.
jsaurabh10 months ago
Thanks for such a wonderful instructable. After this, I too am not afraid of LEDs. Now, they are my friends too.
i have a big problem i think ull solve it perfect.
i had connected 50 leds parallel to 6 volt battery its working without any problem for 5 hours, i didnt use resisters is there any problems
this has been discussed all over the web. The more leds you use in parallel the less resistance (resistor) is needed before the voltage source. if you used one led and a voltage source of 6volts it will get hot and eventually pop. you can acutally buy led holiday lights from stores that will have hundreds in series or parallel. If you plug it into the wall it will work just fine but if you take one of the leds out of the circuit and plug it into the wall it will pop in no time. I am not onehundred percent sure if what I am saying is correct but I have read it on multiple threads, i have never tested it out.
What are the voltage and current requirements of your LED's??
donmatos2 years ago
Thanks for such valuable information. For me it was like rain falling on the arid soil of the Brazilian northeastern backlands, lowering the dust that prevented us from seeing our crops. Now, I can pick some fruit. But I have a question that may be the subject of his next insructables: AC 220V in, I could turn (turn) 70 LEDs without using resistors? Thanks be to find time to answer, if not, thanks anyway.
I can't answer your question, unfortunately, but I would like to second your beautiful analogy about the Brazilian backlands - this clarifies so much that was baffling this ageing non-scientific-arty-type that I feel I've finally understood something to do with this most arcane of topics. Thanks noahw!
nbagf donmatos1 year ago
I know this response is late, but it actually is not possible because LEDs run on DC (Direct Current) power and your main 220 volt house line runs on AC (Alternating Current) as you said. It is possible but not very realistic.
donmatos nbagf1 year ago
Mesmo assim agradeço o empenho. Sei que o tempo é ave de rapina pra maioria de nós. Sobre os leds eu compreendo que é uma realidade meio estranha, mesmo. Valeu a pena, ainda.
nbagf donmatos1 year ago
Thanks to an online transator (not always great) I understood your reply! Thanks for the response and I'm glad you know now. If you do take up this project you should create an 'ible on it! It would be interesting!
jli51 year ago
I have a question about wiring together in series, LEDs with different forward current values.

I want to wire to wire together 4 LEDs to a 9v battery in series.
2 of the LEDs have:
3.0-3.4VDC Forward Voltage
20mA Forward Current
Other 2 LEDs have:
3.0-3.4VDC Forward Voltage
80mA Forward Current

How would I find out the resistance/resistor I need?

Also, if I want to wire a computer fan with DC Voltage of 12V and current of 0.12A
to two LEDs:
1st LED) 3.0-3.4VDC Forward Voltage and 20mA Forward Current
2nd LED) 3.0-3.4VDC Forward Voltage and 80mA Forward Current

to one 9V battery, what resistor would I need and how would I wire them together?

Thank you in advance!
jjz1 year ago
Very insightful and concrete info. Bravo!
Ben Finio1 year ago
Just to reiterate a few older comments below (since this is one of the most popular Instructables on the site) - soldering to batteries is a safety risk and they can explode. Don't do it. Battery holders are cheap and easy to find:

as are clips that fit onto 9V batteries.

For the novice: a "battery holder" is just a plastic box with metal springs inside that push up against the battery terminals, and wires sticking out of the box that you can connect to your electronics project. It's safe to solder to the wires. You can get them in many different sizes (e.g. 2xAA, 4xAA, 8xAA, same for AAA, they make coin cell battery get the idea) and some have built-in on/off switches which are convenient. The number of batteries you need will depend on your project, but in general battery holders connect the batteries in series, so the voltages of the individual batteries add up. A typical AA or AAA battery you get at a store is 1.5V - so two of them will give you 3V, four will give you 6V, etc.
maxx-on1 year ago
As alexparting101 said:
> You should put a resistor in series with each LED as any vdrop differences will result in uneven sharing of the current. (especially as the LEDs age).

However, you can do this anyway. Check the voltage that the LED is rated for. Divide the driving voltage (6V) by the LED rated voltage. Put that many (and perhaps another to ensure that it doesn't over drive the LEDs) in series and that will allow you to have the LEDs light without a resistor. Putting more LEDs will cause them all to dim. The more you put, the dimmer they get.
New world, thanks!
vivdal1 year ago
An excellent and cogent explanation that is easily applied.
Thank you very much it has really enabled progress.
Well Done****
You should put a resistor in series with each LED as any vdrop differences will result in uneven sharing of the current. (especially as the LEDs age).

keys881 year ago
people please try not to solder anything to a battery. if the get to hot they can explode.some batteries easier than's easy enough to just buy or pull out of something else a battery clip/holder.
techguy561 year ago
In seeing this "article" on wiring multiple led-s, I am seeing 2 resistors in series and 2 led's in parallel. Is that Really the way you wire multiple led's? I was under the impression that while wiring led's together.. in parallel, you have one resistor on each led to keep the led safe.
BigMrTree1 year ago
Great Job!! Thanks for making it so simple to understand!! This is exactly what I was looking for!!
rwallett1 year ago
Great intro, cheers
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