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Picture of GUIDE TO LED PROJECTS
INTRO.

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.
 
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Step 1: KNOW YOUR LED

Picture of KNOW YOUR LED

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.

Step 2: KNOW YOUR LED

Picture of KNOW YOUR LED
If you are interested, here you can see the different parts on an LED.

Step 3: RESESTORS TO BE USED WITH LED's

Picture of RESESTORS TO BE USED WITH LED's

This set of rules will help to build a Project, follow them.

Here I have shown the Resistors to be used with 6 volts, 9 volts and 12 volts DC.

You can go on adding any numbers of LED's.

Remember that the first line of LED should be in series and  the second line onwards should be in Parallel.

Step 4: USING LED's WITH AC TRANSFORMERS.

Picture of USING LED's WITH AC TRANSFORMERS.

LED can be run on AC or DC current.

If you want to run it on DC that is Battery Then you must use Resistors.

If you want to run it on AC then use a Step down AC Transformer. (220VAC to 12 VAC)

Here we will deal with AC Transformer

Now what is the load the AC Transformer will take? For that you will have to measure the output voltage of the AC Transformer with a Multimeter, say it comes to 14volts.

The subject transformer was 14VAC 500mA output without load.

First, we have to be aware that the 14V rating is known as the RMS voltage, and is the effective average power of the sine wave. The maximum voltage, which we will subject our LED’s to, is about 1.4 times higher.

So we should expect a peak voltage of 1.4 x 14v =19.6

So, we will be using 19.6 volt as the basis of our calculations.

We know that most white and blue LED’s range between 3 and 3.6 volts. So by dividing our PEAK voltage by an average LED voltage, we get an idea of the number of LED’s our transformer can support:

19.6 / 3.5 = 5.6, which we round up to 6 LED’s.

But remember, that AC has an identical NEGATIVE cycle! Which means we can add a mirror circuit that work on alternate phases,

that is 6+6. The advantage of using voltages to start our calculations is that, as long as we stay with similar LED’s, and stay within

its operating voltages, the current will stay within safe limits. So, by adjusting the number of LED’s in use, we can handle most AC

transformer outputs. We can multiply the light output up to 15 times just by adding chains of 6+6 LED’s arranged the same way

across the supply! 15 times means 90+90=180 LED’s
.

Step 5: LED's CAN GLOW DIRECT ON 220volts or 120 volts AC MAINS.

Picture of LED's CAN GLOW DIRECT ON 220volts or 120 volts AC MAINS.

You can use LED’s directly on 220 volt or 110volt AC.

Same principal applies, one line opposite to the other while using AC.

The value of the Condenser and Resistors are given in the diagram for 220 volts and 110 volts.

The condensers must be non-polar.

You can use 30 + 30 LED's on a string, after that if you start adding more LED's the light starts to get dimmer.

 

Step 6: USING 1 WATT LED’s

Picture of USING 1 WATT LED’s

Here you can see the various types of 1 watt LED’s.

Their polarity are marked on the legs or body.

They glow on 3 volt and consume 350mA of current,

so you must calculate the power source to be used with this LED.

Step 7: USING 1 WATT LED WITH BATTERY.

Picture of USING 1 WATT LED WITH BATTERY.
Every thing is explained in this Diagram.

Step 8: RESISRORS TO BE USED WITH 1 WATT LED.

Picture of RESISRORS TO BE USED WITH 1 WATT LED.

You can use different types voltage and resistors with this LED as shown in the Diagram.

Step 9: USING STRIP LED IN YOUR PROJECTS

Picture of USING STRIP LED IN YOUR PROJECTS
Everything is clearly explained in the Diagram and it is very easy to use strip LED's.

Now you can make your own LED projects.
bhuvanamani2 months ago

sorry sir i am not enough . having any converter from 6 v to 4 volt converter

bhuvanamani2 months ago

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.

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

Jayhoffmann4 months ago

does this actually work for powering LEDs on AC mains? : http://www.instructables.com/file/FIVRUBHH8TTP6SY

Dipankar (author)  Jayhoffmann4 months ago

Yes

HamedH5 months ago

i try to run 100 led with 220v ac but when i connect supply my board is explode

i have some injury in my hand and face tell me where i have mistake?

Dipankar (author)  HamedH5 months ago
You are lucky that you escaped from heavy injury, NEVER connect LED's directly to 220 AC mains.
Here is a circuit follow it......
STEP-3 TL.jpg

hello i want to know one thing .. plz someone tell me what resistor should i use to connect a LED with 220V AC?
=>Bhaskar

Dipankar (author)  bhaskar.p.deka5 months ago

Follow this circuit..............

SLL-04.jpg
partha_roy8 months ago

Sir, how to connect 1 watt led on 220 volt ac.

Dipankar (author)  partha_roy8 months ago

You have to use a Transformer, SEE my

24 Watt LED Lamp. and you will get the idea.........

24-4.jpg
dearshubham9 months ago
Sir i have 21 led i want to run in car please suggest me
Dipankar (author)  dearshubham9 months ago

Use 4 LED's in series and 5 rows.

Car.jpg
MikB2 years ago
Your "+" and "-" 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 "-", and the flat line at the point is "+".

A positive voltage needs to be applied to the "-" terminal, to make it conduct. The "+" terminal goes toward ground.

In the LED physical picture, the LARGE part of the metal (anvil) is the "+" terminal that goes toward ground. Not the "-".
MikB MikB2 years ago
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 "electronic symbol" directly above it ... Oh well :(
Dipankar (author)  MikB2 years ago
It is the same picture borrowed from http://en.wikipedia.org/wiki/LED.
The arrow showing the direction of the current.
MikB Dipankar2 years ago
The + and - are all still backward throughout this tutorial -- it's not helpful to teach people backwards.

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.

Also the "AC" 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.
Dipankar (author)  MikB2 years ago
The 12v transformer does not need a resistor as the 6 LED's take care of that.
MikB Dipankar2 years ago
That deserves a good technical explanation, as to how the LED's "take care of" 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.
Dipankar (author)  MikB2 years ago
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.

I totally agree!!

MikB Dipankar2 years ago
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.

There are better ways to learn about LEDs than by destroying them.
Dipankar (author)  MikB2 years ago
The Positive current flows from the (+) side through LED to the (-) side which is the ground.
andyboy0072 years ago
ok, thanks for the clarification, friend.
Dipankar (author)  andyboy0072 years ago
You are welcome..............
andyboy0072 years ago
Then I saw, just do not understand why in uploaded some (low voltage) resistors have less than 1 watt of power dissipation
Dipankar (author)  andyboy0072 years ago
LED calculator
This is the new version of the single LED series resistance calculator, good for when you have a single LED and need to know "what resistor should I use with my LED?" 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
3.6 = Source voltage
3.5 = diode forward voltage
350 = diode forward current (mA)

The wizard recommends a 1/4W or greater 1 ohm resistor. The color code for 1 ohms is brown black gold.
Link to this solution: http://led.linear1.org/1led.wiz?VS=3.6;VF=3.5;ID=350 *

This
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.
LED calculator version 2.0 Copyright 2001-2006, Rob 'linear' Arnold. All rights reserved.
andyboy0072 years ago
hello, I'm brazilian, so forgive my english via google translator.
I would take a question about links with leds 1 watt ...
if they have a watt of power, the resitor attached to them ñ should also have a watt or higher? sorry for the ignorance, I'm new in electronics
Dipankar (author)  andyboy0072 years ago
See step-8. The resistors given for the different DC voltage is correct for a 1 Watt LED.
mathman472 years ago
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.
Dipankar (author)  mathman472 years ago
OK, I have removed the double arrow as it creates confusion.
MikB Dipankar2 years ago
So now they're not LEDs any more. They're just diodes, with the polarity mislabelled.
Dipankar (author)  MikB2 years ago
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??????????
MikB Dipankar2 years ago
"We have a "be nice" comment policy. Please be positive and constructive with your comments"

Did you miss that?

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.
Dipankar (author)  MikB2 years ago
USING LED's WITH AC TRANSFORMERS. is the heading so it cannot be any other thing, and surely people will understand the meaning.
rimar20002 years ago
This is very useful, Dipankar, thanks for sharing.
Dipankar (author)  rimar20002 years ago
Now you can make your own LED projects.
antoniraj2 years ago
I recently bought few Rigid Strip LEDs of 12 v each. Do they need additional resistors or can be connected directly to battery? It seems that everything is built into it..
led.JPG
Dipankar (author)  antoniraj2 years ago
They do not need additional resistors, use a 12 volts battery or the adopter which came with it, to 220 volts mains.
3 v 750mA - 50 (15mA each )leds who much is it watt ?