I had to do this project for many of my young friends who are interested in LED’s but do not know how to go about it.

I also had the same problem but was fortunate enough to get HELP from my friends at www.Instructables.com.

This is not about any calculation or study but a set of proven rules to follow and get results,

which anybody can do if he has the mind to.

Here I have shown you many types of power supply which can be used to glow a LED.

I have also shown here how different types LED's can be made to glow and use it in you project.


A 15 mm LED has two legs, the long one is the Positive and the short one is the Negative.

It consumes 15 milli Ampere of current and can glow on 3 Volts DC Current, or a 3 volt battery.

LED’s are Diodes and the current can only pass through the POSITIVE side.

Always remember to maintain the POLARITY of the LED, that is (plus to plus) and (minus to minus) otherwise it will not work.

LED is a one way street. Now you know how to connect an LED in your circuit.

Sir in my project I used 25leds which work in 230v by using 4 1n4007 ,1 22ohms 0.5w, 1 1M 0.5w, 1 0.22mfd 400v and all glows but after some time some led are not working and how to overcome it
<p>Use this circuit, </p>
Sir in this how much led can be used as maximum
<p>Use 15+15 = 30 LED's ......</p>
<p>sir I want to how to connect 50 leds series in 220 volts (lighting decoration utilization marrieges or functions )I made 100 led sets. 20 sets put in derect current without any circuit or resistence 20 sets were burnt so please help me sir which circuit or resistance and capacitor use </p>
<p>Use STRIP LED's, they come in 5 Meters length and has its own Adopter......</p>
<p>led seriel mean 50 leds solder 25 meters wire it will come more lanth and save money. strip leds are not hanging in street. now iam using 2k2 2watt resistor but change daily because they burnt. so plz tell me permanent solution </p>
<p>Not possible without Transformer................</p>
<p>Hello Sir.<br>I have a couple of questions.<br>1) If i use a 3.7 volt cell phone battery with the 1 watt 3.5 volt LED, will this slight 0.2 volt (3.7-3.5 volt) potential difference still require a resistor or its OK to use the LED directly without damaging the light?<br>2) LEDs tends to get hot in prolonged use. What can be done to counter this heating? <br>THANKS !</p>
<p> 1) You can use directly.</p><p>2) Use a heat sink.</p>
<p>Hello,</p><p>I would like to add these LED together ( I have 2 pairs which is 4 of them) but I'm not sure if I need additional resistor or just simply connect them in series ( + to - ) then connect to the source which is the 12V battery ( car) . The seller only mentioned this is 12V 9watts LED. Please help !!! </p>
<p>Unless I know what type of LED's, <em>I will not be able to answer your question......</em></p>
<p>but since we know it is 12V 9watts for each lamp and each lamp contained 2 LEDs therefore can we use this formula P = V x I =&gt; I = 9 watt / 12V = .75 A thus .375 A for each LED in one Lamp ? </p>
Dear sir which resistot is good for single 1w led to connect 12v battery
<p>27 Ohms 3.3watt</p>
<p>sorry sir i am not enough . having any converter from 6 v to 4 volt converter<br></p>
<p>Hai sir iam manikandan from tamilnadu. i need some answers from LED s. i have 6 volt lead acid batery and 1 watt LED . How many LED connect to the battery. </p><p>i think 1 watt LED high britness for 3.7/8 volt DC. so i give connect to 2 LED. so i enough britness this LED . so what i do sir ,help me . my 1 year project pls my thinking pls<br></p>
<p>does this actually work for powering LEDs on AC mains? : http://www.instructables.com/file/FIVRUBHH8TTP6SY </p>
<p>i try to run 100 led with 220v ac but when i connect supply my board is explode </p><p>i have some injury in my hand and face tell me where i have mistake?</p>
You are lucky that you escaped from heavy injury, NEVER connect LED's directly to 220 AC mains.<br>Here is a circuit follow it......
<p>hello i want to know one thing .. plz someone tell me what resistor should i use to connect a LED with 220V AC? <br>=&gt;Bhaskar</p>
<p>Follow this circuit..............</p>
<p>Sir, how to connect 1 watt led on 220 volt ac.</p>
<p>You have to use a Transformer, SEE my </p><p><a href="http://www.instructables.com/id/24-Watt-LED-Lamp/" rel="nofollow">24 Watt LED Lamp.</a> and you will get the idea.........</p>
Sir i have 21 led i want to run in car please suggest me
<p>Use 4 LED's in series and 5 rows.</p>
Your &quot;+&quot; and &quot;-&quot; designations are backwards compared to normal electrical teaching: An LED is a diode and follows the same rules as other diodes. The base of the triangle is &quot;-&quot;, and the flat line at the point is &quot;+&quot;. <br> <br>A positive voltage needs to be applied to the &quot;-&quot; terminal, to make it conduct. The &quot;+&quot; terminal goes toward ground. <br> <br>In the LED physical picture, the LARGE part of the metal (anvil) is the &quot;+&quot; terminal that goes toward ground. Not the &quot;-&quot;.
It would help if the intro picture you borrowed from http://en.wikipedia.org/wiki/LED had the designations the correct way round! It's not consistent with the &quot;electronic symbol&quot; directly above it ... Oh well :(
It is the same picture borrowed from http://en.wikipedia.org/wiki/LED. <br>The arrow showing the direction of the current.
The + and - are all still backward throughout this tutorial -- it's not helpful to teach people backwards. <br> <br>The arrows do not indicate direction of current, it's just to show emission of light. A photo diode/photo transistor has arrows pointing towards it to show reception. <br> <br>Also the &quot;AC&quot; LEDs on a 12v transformer still need a current limiting resistor, otherwise they will be damaged. LEDs don't run on voltage, they need a controlled limited current.
The 12v transformer does not need a resistor as the 6 LED's take care of that.
That deserves a good technical explanation, as to how the LED's &quot;take care of&quot; limiting their own current. I'm not sure there is one. That's why you need a resistor, or a current limiting circuit. All you'll do is end up damaging LEDs.
I am not an Electronics engineer but if you see my LED GLOBE posted in June 2011, it has more than 200 LED's and no resistors, but it is still working without a single LED being damaged. So you please explain how is it still working till date? Being too technical sometime does not pay. We are practical people so what works for us is OK with us.
<p>I totally agree!!</p>
I looked at your LED globe, it is a fantastic idea, and looks great. I will say though that two people there also commented on the NEED for current limiting in some form, and I agree with them, if this is still working it is down to luck, and not design. <br> <br>There are better ways to learn about LEDs than by destroying them.
The Positive current flows from the (+) side through LED to the (-) side which is the ground.
ok, thanks for the clarification, friend.
You are welcome..............
Then I saw, just do not understand why in uploaded some (low voltage) resistors have less than 1 watt of power dissipation
<div class="txt comment-txt"> <strong>LED calculator </strong><br> This is the new version of the single LED series resistance calculator, good for when you have a single LED and need to know &quot;what resistor should I use with my LED?&quot; This calculator determines that for you. The LED series/parallel array wizard is available for those of you who need to do calculations involving more than one LED. The wizard will help you pick the resistors make the connections for any number of LEDs. LED calculator: current limiting resistor value<br> 3.6 = Source voltage<br> 3.5 = diode forward voltage<br> 350 = diode forward current (mA)<br> <br> <strong>The wizard recommends a 1/4W or greater 1 ohm resistor. The color code for 1 ohms is brown black gold.<br> Link to this solution: http://led.linear1.org/1led.wiz?VS=3.6;VF=3.5;ID=350 *<br> <br> This </strong>calculator rounds the resistance up to the next standard resistor value. You should actually be able to buy a 5% resistor with the value returned by the calculator. ** Power calculations assume use of the standard value current-limiting resistor shown above. Resistor power ratings are chosen based on operating within 60% of the rated value.<br> <strong>LED calculator version 2.0 Copyright 2001-2006, Rob 'linear' Arnold. All rights reserved. </strong></div>
hello, I'm brazilian, so forgive my english via google translator. <br>I would take a question about links with leds 1 watt ... <br>if they have a watt of power, the resitor attached to them &ntilde; should also have a watt or higher? sorry for the ignorance, I'm new in electronics
See step-8. The resistors given for the different DC voltage is correct for a 1 Watt LED.
Nice Instructable, quite useful for those getting started with LEDs. However there is still an error in the schematic. The double arrows indicate that there is light output, not the direction of the current.
OK, I have removed the double arrow as it creates confusion.
So now they're not LEDs any more. They're just diodes, with the polarity mislabelled.
<strong>I was going through your page and I found that you do not have any Projects posted so you are just a talker rather than a doer. You only love to comment on other people's projects rather do you own?????????? </strong>
&quot;We have a &quot;be nice&quot; comment policy. Please be positive and constructive with your comments&quot; <br> <br>Did you miss that? <br> <br>I'll leave you to make your personal comments and insults, I'll leave others to work out whether you have any idea what you're doing. <br>
USING LED's WITH AC TRANSFORMERS. is the heading so it cannot be any other thing, and surely people will understand the meaning.
This is very useful, Dipankar, thanks for sharing.

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Bio: Now I am a retired person, who enjoys life and making small things to pass the time keep myself busy.
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