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.***

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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1$ or 2$ per led? you can find 100 5mm leds with 2-2.5$ on ebay

Kaarst8 hours ago

very nice lesson for me, thanks

I've played with LEDs, batteries and small motors with my kids in making circuits but I don't recognize the beige block you're using with the holes in it. Where does the soldering come in? I am apparently even more beginner than you. :)


No soldering necessary!

You can find them online and cheapest from Chinese sites

chintans12 hours ago

Can I use 5mm LED with 1V 1A load?

chintans13 hours ago

Can a 5mm led take 1v 1a load?

ktalex5 years ago
so if i use a 3v led and running 5v as power what resistor should i use? im noob sorry.
JimR2 ktalex14 hours ago
3 volt will just make your led put out more light but shorten it's lifetime :-)

Search on google for ohm voltage calculater. Don't invent the wheel tvice as one says. :-)

There is no such thing as a 3v led! If you have a led with a forward voltage of 3v it is presumably a high intensity led with a rated forward current of about 20mA (0.02A). With those figures the resistor would be (5-3)/0.02 ie 100 ohmsrated at least at 0.04 watt (2 x0.02)

a resistor with color code brown, black, brown, gold would break even but brown, brown, brown, gold would be a better choice
EfrainM114 hours ago

that is very truth...NEVER SOLDER INTO A BATTERY!!! EVER!

If you can find some LM3909 chips it will give you a lot more options

tonep17 hours ago

There is no accounting for human beings' facination for lights! This Instructable was published 9 years ago. More than 2 million views and 675 comments later this thread is still alive, with some commenting 2 hours ago to comments that were written 7 years ago. Fascinating!

Nicely written Instructable, noahw. Just a few relevant points regarding wiring up LEDs:

1. Never connect an LED to a power source (battery or other power supply) without a series resistor. The internal resistance of the battery as a series resistance is a good excuse for omitting the resistor, but as long as you haven't measured the actual internal resistance, you don't know how much current is flowing through the LED - it can easily be close to burning point of the LED. NEVER OMIT THE SERIES RESISTOR.

2. You don't need to bother yourself calculating the series resistance value. Just google for a "LED resistance calculator". They are all easy to use. Just enter the voltage and current of the LED and how many are in series/parallel and you get the resistor value. To be on the safe side, use a value that is on the higher side of the calculated value. Some even have a table to guide you with the various voltages and currents of LEDs based on colour.

3. If you are using many LEDs of different colours make sure that all the same colours are wired together (series or parallel - depending on your circuit).

4. If you have a fixed low voltage power source (e.g. 3V battery) and you have to wire a few LEDs together, consider using a parallel circuit. Use one resistor for each LED. If you have all the LEDs connected togetler in parallel and one series limiting resistor to the power source, if one of the LEDs goes open the current through the remaining LEDs increases and another one may blow after some time.

5. If your power source is to be decided by you, e.g. 9V or more, consider a series (or series/parallel) connection. See Berrydueds below.

I hope this helps.

NoelT120 hours ago

Basics, like this article are great for those of us who would like to try messing around with electronics but don't know anything. Your style of explanation was very easy to follow, great article and very helpful.

Jamebonds120 hours ago

I would recommend you to using three resistor for three LED in parallel. It is better than just one resistor. As for programmable chip, they all need have all LED's own resistor each. As if only one light are lit while 9 out of 10 are not lit, it won't limited to 20mA.

I have 3 packs of 2700 ohm 1/2 watt 5% tolerance resistors , what I can I do with that and LEDs?

sko565 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?

copy and paste from someone how as already done it, you can borrow some of mine if you like Ω Ω Ω Ω

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.
robin677 years ago
hey! great info, does it mater what side of the resistor is soldered . a certain colour toward the power source or vice-versa?


no, solder it anyway you want
Welch767 years ago
I'm new at this. I'm planning to make a banner with 3 letters D-A-D made of LED like the ones in Asian Concerts. I'll be using 38 2.1v of LEDs. RadioShack (w/c monopolized the LED world) gave me 2AA batteries for power source(w/c I'm clueless about it.) Now comes the prob, what the name of shishkabob is a resistor and what does it do? So sorry for a stupid question but I don't even know how this thing works. and how to make it. I'm planning to put it on a cardboard. Thanks in advance. c",)

It is not a stupid question. A resistor is an electrical component which, in the case of a simple led circuit, sets the current which passes through the led (this, in turn adjusts the brightness - the more current the brighter the led). Your leds have two relevant ratings - the maximum forward current and the forward voltage drop. Presumably your leds have a forward voltage drop of 2.1v. Of greater importance is the max forward rated current - let's assume this to be 10mA (0.01amp). Connecting the two AA cells in series will give a supply voltage of 3v. to supply a single LED the series resistor will need to be (3-2.1)/0.01 ie 90 ohms (the nearest standard value is 100 ohms using this will reduce the current slightly. You would need to repeat that for each LED - your AA batteries won't last too long though!

A resistor is a device that limits the current. They are made usually of ceramics that conduct electricity, but not very well (semi-conductor). If you have a stream with nothing but water, the water will flow well, but if you throw a bunch of big stones and debris into the stream, the water is slowed down.
ghavo5 years ago
Great article... Quick Question... Does it matter which end you put the resistor? On the Positive or the Negative side?  Thanks!!!
clarkt ghavo5 years ago
Absolutely.    If hooked up backwards the LED will not light up ever.   There is a positive and a negative terminal.   There is also a flat place next to one of the wires on the LED.  This is the negative wire.   Also if you are using a new LED  one of the wires will be longer than the other.   That will be the positive.  

Here is a page that gives a bit of explanation.


NOT NECESSARILY. Always check the data sheet for the LED.

As long as you have the resistor in series with the LED it can go in either the anode or cathode lead - observe the correct polarity of supply to the led

X-22 ghavo5 years ago
so long as the resistor is in series it doesnt matter at all, the electrons have to pass through it and where ever in the circuit it is it will reduce the total current
verence ghavo5 years ago
Not. At. All.

kamenkoo4 years ago
I want to connect LED to my speakers.. :)) How can i do that ?? :)) What should i do?? :)) Thanks :)))

Why? If you want a pretty light show that changes with the music, you need to make a driver module for the LEDs ideally with seperate channels for different frequencies of sound and drive it from your pr-amp or line output, as the speaker output stage is unlikely to be able to handle it and is not a suitable dc voltage source (in fact it is a very variable ac source)

Use a transistor. just google transistor tutorals. To find out how to use them, if you still need more help ask me.
Berrydueds3 years ago
I have trouble with my Leds, The schematics are below.
My problem is that the middle row of Leds always gets burnt out.
The first time I didnt use any resistors and the middle row completely burnt out but the rest were fine.

Second time, I only had 470ohms 1/4W resistors. Same issue - the middle row burnt out.

Also, i only have 470ohms resistors, if i used the right amount (100 ohms ) would this solve my problem?

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