Picture of 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

Picture of 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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GrantK52 days ago
Just to throw this out there in case any of you start playing with resistors in series and parallel. the method he stated determing equivalent resistance in series is correct. But the method he used for resistors in parallel is only accurate for the same sized resistors. The actual equations are as follows:

n=total number of resistors

Rtotal = R1+R2+...+Rn

1/Rtotal = 1/R1+1/R2+...+1/Rn
or simplified
Rtotal = 1/[1/R1+1/R2+...+1/Rn]

Hope this helps anyone messing with differet value resistors figure out any issues they have been having. Other than that great ans simple instructions on LEDs!


Well done - thank you! I want to teach my 13 year old grandson a little about electronics using LEDs. It's been a long time since I did this kind of stuff & I didn't want to embarrass my self too badly (or flounder around and have him get bored).

Yeah - really basic, but that's what I was looking for. It helped.

Dave854 days ago

I thoroughly enjoyed this beginners guide to LED. I did a lot by trial and error but this eliminates my need to do it inefficiently. Great post!!!

DerekP3 months ago

I am new to electronics, and I have a Nintendo 64 that I want to wire roughly 16 LEDs into. I have seen many people use a 5 volt power output on the board. Should I wire the LEDs in parallel or series?

T0BY DerekP17 days ago
Are you pimping your N64? How does it look?
FarisB DerekP28 days ago
Parallel :)
PrashantS518 days ago
sir I want to install 2 10 w led with 12 v power supply. so what's the steps to install it . Please describe either I join this in parallel or series. what is the power of resistence. would I have to use led driver.
dhermann21 days ago

This was an excellent beginners tutorial. I had forgotten a lot over 30 years of not using my basic electronics knowledge I learned in the military and this helped me remember it.

Good work with your explination and instructions.

mizami4 months ago

Say i have 12V power supply and 15 LEDs. i decide to make three loops of parallel LEDs (3.6V each) and arrange them in series (i.e one loop has five LEDs arranged in parallel and the three loops are connected by series). This means for every loop, there is approximately 3V to power adequately.

Question is do i still need to put resistor in front of LEDs since theoretically i have used voltage power effectively? If yes, do i put the resistor in series of each LEDs or in series of every loop?

FarisB mizami28 days ago
Hello, What I assume it is better to use a resistor for longer lasting of LED.
JinkyDrew1 mizami4 months ago

i dont thiink you would need one. but im not certain, send a pic :D

Hey man I love shrek, shrek is love shrek is life

How do i turn a led on cause im dum and dontthr no what im doin so pls help me wire up a led thnks

For beginners I suggest to have these items to test and understand the concept of making an electronic circuit

1 220 Ohm Resistor
1 Breadboard
Set wires (1xRed)(1xBlack)
2 Light Emitting Diode(LED)
Switch or Variable switch

Test in series first than parallel

In series your first LED should be brighter than the second LED

In parallel both of your LED should have the same brightness

Here's a tip
When you're running parallel the voltage will remain but the current don't
If you run in series the voltage will increase while the current remains.

Hope this helps :))

pwrmac76001 month ago

So If I understand this correctly. If I am wiring 5 LEDs in parallel that are 1.9v per, and I am powering them off of a 9.6v 300ma power supply, then I would need a 60ohm resistor in between each LED? does it matter how many watts the resistor is?

MickiG11 month ago
priandoyo1 month ago

Thank you for clear explanation, I spend days to realize this.

dave.callista2 months ago

I have a machine that has two indicator lights and neither one is working. I opened one up thinking it had a burned out bulb, but instead, it contained 3 LEDs. The machine's wiring diagram shows 6 volts AC applied to the indicator terminals. I tested and 6 volts AC is present. I must assume that there is some circuitry tied to the LEDs that rectifies the AC. I would like to get this fixed but have no idea what to do. I can use a multi meter, and soldering iron, if someone will tell me what I need, and how to connect the components.

Oh so whit u hav to do m8 is recharche ur battery so yeah shild fix it r8 me out of 8

cause I r8 8/8 m8 cya later mssg me im starting a utube channel Tips wif James

Dave, LEDs are dioides, thus they are rectifiers themselves. If one of the LED's polarity doesn't match with the others', no current will go through. I would suggest that you test each one independantly with a AA, then make sure they go back into your machine in series (+ to -).

I have tried linking up a resistor and my lead would not glow even with 2 batteries. I have tried connecting to leads in series and thy refused to glow up. PLEASE HELP.

I want to link you about 15-20 LED's in series and power up with 12 volts.

I have already done some projects with LED's in parallel and they are working perfectly.

sko564 years ago
The only reason the LED doesn't Fry from adding 1.5V is because the Alkaline Battery has an internal resistance. Ohms Law Holds true I (current) = V(volts)/R(resistance in Ω) . If there was no resistance the current would be near Infinity causing the Wattage to go through the roof as well (W=I^2*R). same reason a "throwie" works without a resistor.
How do you make an ohm's symbol on a keyboard?

ALT 234 Ω

The easiest way, in Windows, is by bringing up charmap, scrolling down the list until you find the "Ω" symbol, copy it, and then paste it into the window.
You can also hold down the ALT key and type the decimal value of the character but wasn't successful getting the character to print out. My guess is it has something to do with the character map I was using. In any case, I think using charmap is probably the best way to print non-keyboard generated character.
For Mac, just press Option+Z.
In Word or Excel make change the font to "Symbol" and then hold the 'alt' key while typeing 89 on the numeric pad. Or use the Insert” tab, click , and then choose the symbol you want.

Is it possible to prewired LEDs with resistors this way to a 12v battery

itsjustjayok3 months ago

Hi can you tell me if this is correct - I purchased these 50 LEDs connected in series powered by 3 x AA batteries (4.5V) i want to switch to a 4.5V multivoltage adapter instead of batteries but need a resistor to prevent dimming and dieing of the leds.

I know the Voltage is 4.5v and the Current is 10mA so using Ohms Law would i be right in saying that based on a "white" LED generally having a forward voltage (vF) of 3.3V i would need to take the 3.3v from 4.5v to give 1.2v for ohms law

Resisance = 1.2 (v) / 0.01 (10mA)

This gives me a 120 resistor.

adding this in the series would this help? or am i totally out lol

Thanks :)

i have 3x6v led lights that each take 4x1.5 AA battery's

im wanting to wire them to all up so they can be powered by a wall adapter

what power size adapter would i need to do this


Maybe someone on here can answer this for me. I have aftermarket headlights (spec d) on my car. Had em for 2 years and now I have two leds blown out that are part of the eyebrow on the lights. They are wedge style leds with one led on each light. There are 5 LEDs wired in series for each eye brow. You can't buy the LEDs from the company they don't sell them and they won't tell me where to get them. My problem is I tried a 12v led and it wouldn't light up. I checked the voltage and each led in the series only uses 3volts. Where can I find a 3volt wedge (looks like t10) led?!?? Email me at
Rushmoore3 months ago

This was so awesome! Very clear and easy to understand! I had been looking at other sited the whole morning and this was the only explanation that made sense. Thanks you!!

rania.riya.73 months ago

i take an led dim light an remove the 2 resisters and plugged on the switch i can see a lightinig!! and it stoped what does it mean???

You probably blew the LED because of too much power going into it. Try again with a new LED and a bit more resistance.

ahwang4 years ago
I have a question but btw, you have an awesome website for ppl like me who's interested in learning to light up some LEDs!!!

Forward voltage: 3.0-3.2
Current: 20ma
Battery: 6V

1. Following your instruction, I first tested my 2 of my LED, in a series without any resistors to my 6V and baam! it lit up! thanks!
but after about 20 secs, the LEDs started to get hot. Is that normal? I don't think I'd need any resistors or I wouldn't even know how since I would get 0 ohm resistor value

2. My project is to light up 8 LEDs. 4 pararell LED each side, then 2 of 4 pararell LEDs in series. so like. (1+1+1+1) + (1+1+1+1).
so I'm thinking (3V, .08ohm) + (3V, .08ohm) so it would be 6V with .08ohm right?
then it would require no resistor since 6v-6v=0 right?
Or would that get too hot and require resistors?

any help is appreciated!!!
JinkyDrew1 ahwang4 months ago

do the first one with resistor, u were giving the led toooooooooooooooooooooooooooooooooooooooooooooo mich current abd volts

ronym83 ahwang10 months ago

6 volt battery sometimes have more than 6 volt

( it's depend on battery state... it's full... or near empty )

so we must measure the exact voltage of battery using volt meter

if the voltage of battery is... say 6,5 volt

devide it by two we get 3,25 volt...

that's why your LED are too hot... because you over voltage it


just like 12 volt battery which can be 10,7 to 12,8 volt

( it's depend on charge state of battery )

it also can be 14 volt ( if the battery are connecting to the charger )

cellis6 ahwang3 years ago
LEDs power is based on Amperage not Voltage, that's why they are getting hot. Think of them like a resistor, when you put 2 resistors in series, you drop voltage each resistor but Amperage never changes.

So if your LED requires Forward Voltage of 3.0-3.2Vf, and 20mA, and you want to run it off 6V. If you were just trying to power one LED it would be (6V-3.2V)/.02mA. Meaning you'd need a 140 ohm resistor before attaching the LED to power.

As far as hooking them up in series/parallel, you should be able to do it with one resistor at the beginning of each series of 4 of 140 ohms. Which would make each series 20mA and 3.2 Volts after the resistor. Hope this helps.
johnefrancis6 months ago

We built a couple 76 IR Led lights to run off 12 volt batteries for a portable surveillance system. Once the voltage of the battery drops after several hours the led's fade a bit and then go out but the camera continues to run all night because we're using a dc-dc converter to drop the voltage down to 5 volts.

Is there a way to drop the voltage required for the led's down to 5 volts or even 3 volts by adding a single large wattage resistor to the system? If so what's the formula?

Our other alternative is to add a second battery is series to raise the voltage to 24 volts and then use a dc-dc converter to drop it to 12.

Thanks in advance!

give the leds their own batter... if u cant do that a high wattage resistor would also work but sep batters is the best option coz u will get xtreme runtime,... OR a sec batter and high watt resistor togehter will make the leds last longer than the camera

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