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Topic: Super basic question on how to connect LED to a breadboard. Please help! (Read 7978 times) previous topic - next topic

noobtoarduino

Hi Forum,

I am learning to use Arduino and finished the basic starter project where you connect LEDs into Arduino's output pins and make them blink/fade.  I also managed to wire up 3 LEDs (r,g,b) to a breadboard and have that work too.  Now, I want to buy a brighter LED and thought of buying this one from Sparkfun:

http://www.sparkfun.com/products/10179

My question is...How do you connect it to Arduino or a breadboard when there are no "pins" on the Luxeon that I can just poke into a breadboard/Arduino output pin?  I realize this is a basic question but its answer is not obvious to me.  Thanks for your help!


PaulS

You have to solder wires onto the pads on that LED board, and connect them to the breadboard.

Be sure to read the data sheet for the board, BEFORE you connect it to the Arduino.
The art of getting good answers lies in asking good questions.

retrolefty

That is probably not a good device to continue your learning journey. First it is a high power LED requiring a 700 ma constant current driver module to work. And because of it's high power the device needs to be mounted carefully to a compatible heatsink designed to keep the device within in it's maximum temperature ratings. I would search out for more Arduino friendly devices to experiment with.

Lefty


noobtoarduino

#3
Dec 04, 2011, 04:15 pm Last Edit: Dec 04, 2011, 04:18 pm by noobtoarduino Reason: 1
Hi Paul and Lefty,

Thanks for your helpful responses!  So I need to solder it, got it.  

Retro, you bring up an issue that I'd like to learn more about since I want to use a bright LED to illuminate my 9'x8' room.  I just went for one of the brightest LED I could find on Sparkfun.

What is a constant current driver module?  Are you saying I cannot just solder the pads with wires that connect to Arduino output pins?  Please help me to understand what you mean, thanks!

Paul, I just read the datasheet.  It's filled with all kinds of graphs and sciencey jargon that my art student brain can't comprehend.  What do I need to know..or what's important in the datasheet that I should look out for?  Thanks!~

retrolefty

What is a constant current driver module?

It's power circuit designed to convert a voltage source to a current output at a specific and regulated current value, 700ma for the device you have selected. Power leds are designed to run at a specific current value, 350 ma , 700 ma, etc. An Arduino output pin is not a contant current output but rather a voltage level output and has a maximum current rating of 40ma, so no way to wire that high power led device directly to a arduino output pin.

 Are you saying I cannot just solder the pads with wires that connect to Arduino output pins?

That is correct.

 Please help me to understand what you mean, thanks!

The device you are planning on using is but just one component of several you need for an arduino to control it. You require a DC power supply able to supply the voltage and current requirements to then drive a constant current module rated at the current required by the led device, and finally you need a proper heatsink mounted to the led device to prevent it from overheating when running at it's rated power.

Lefty


PaulS

Quote
What do I need to know..or what's important in the datasheet that I should look out for?

It's what Lefty pointed out. The LED board requires orders of magnitude more current than the Arduino can provide. The data sheet says that the LEDs draw 1000 milliamps of current, while the Arduino can safely deliver about 20 milliamps.

Trying to draw 1000 milliamps will result in the Arduino shutting down, hopefully, but not guaranteed, before damage occurs.
The art of getting good answers lies in asking good questions.

noobtoarduino

#6
Dec 04, 2011, 05:08 pm Last Edit: Dec 04, 2011, 05:12 pm by noobtoarduino Reason: 1
Thank you BOTH so much for taking the time to explain these things to me.   So it looks like I need to buy 3 more things to complete my little project.  Can you tell me if I've found the right things online before I buy it?

1. DC ADAPTER.  I have a black adapter that I can plug into the wall, and the info on the big black box says "Output: 5volt/1000ma, Input: 100-240V~50/60mhz".  I am a little confused since I've always called these things an "AC adapter".  Here is a link to the exact thing that I have:

http://store.fungizmos.com/index.php?main_page=product_info&cPath=76&products_id=401

Is it a DC adapter or AC adapter?  Will this work for my project since it provides a direct current of 1000ma?

2. HEAT SINK.  I found this in the same section as the Luxeon LED I want to use:

http://www.sparkfun.com/products/9639

My question is how the Luxeon light I intend to use connects to this heat sink?  The Luxeon light looks like it has a "breakout board" although it's not obvious how the sink connects to the board.  Please explain?

3.  CONSTANT CURRENT DRIVER MODULE.  I searched for this on Sparkfun and got only 1 result:

http://www.sparkfun.com/products/9642

Is this what I need?  My guess is that it's not good enough because it says it only provides 300ma when I need 700ma.  Can you recommend a part from any other site that will accomplish what I need to do?

Again, THANK YOU SO MUCH FOR YOUR WONDERFUL GUIDANCE!

PaulS

Quote
I've always called these things an "AC adapter".

An "AC adapter" converts AC voltage at some level to something else. That can be AC at a different voltage. Or, it can be DC voltage, at some level. When the output is DC, the device is technically a DC adapter. We won't laugh at you if you still call it an AC adapter.

Quote
Will this work for my project since it provides a direct current of 1000ma?

It will, although it is running at its maximum output, so it will get warm. A 2000mA device would run a lot cooler.

Quote
The BuckToot operates with input voltages from 5 to 28VDC and can supply up to 350mA.

So, no that constant current device will not work. It does not provide enough current.
The art of getting good answers lies in asking good questions.

noobtoarduino

Hi PaulS,

Ok, I will call it a DC adapter from now on.  :)

You've helped me a lot, not just on this question but I recognize you from questions I've asked in the past. 

Looks like you responded while I was still editing my questions to be more complete.  I saw later after I posted that the Bucktoot won't provide enough amperage for my Luxeon.  Can you suggest where to buy a current driver from any website that will work for my project, since Sparkfun doesn't yield any more results. 

Also, do you know how this Luxeon light attaches to this heat sink?  Is it even possible?  I'm trying to understand what RetroLefty was telling me to do.

http://www.sparkfun.com/products/10179
http://www.sparkfun.com/products/9639

PaulS

Quote
This is a breakout board for the very high-intensity LUXEON Rebel General Purpose White LED. The board is designed to dissipate damaging heat away from the LED to the back of the board.

So, the heatsink then needs to get the heat away from the back of the board. Heat sinks generally need some heatsink paste to conduct the heat from the source to the sink.

As to how to power them, I don't know. It be google time for you, I think
The art of getting good answers lies in asking good questions.

GoForSmoke


I want to use a bright LED to illuminate my 9'x8' room.  I just went for one of the brightest LED I could find on Sparkfun.


So you need power, possibly a resistor, a switch, a heatsink of some kind (read: metal lamp shade or bracket?), and maybe a pot to vary the brightness with.

Or perhaps you want something more than a simple room lamp?



Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

noobtoarduino

#11
Dec 04, 2011, 08:27 pm Last Edit: Dec 04, 2011, 08:31 pm by noobtoarduino Reason: 1
Hi GoForSmoke,

I just want a simple room lamp that I can fade using the Arduino (kind of like the basic fade LED project that everyone does to learn Arduino, but on a bigger, BRIGHTER scale).  

Is there a tutorial somewhere that shows how to do this?  I have no electronics experience and I need a sense of what connects to what so that it all fits together.  I don't know how I would connect the resistor, switch, heatsink, pot, and power.  I don't even know what a switch or heatsink looks like or which one to get.  Any help on how to do what you suggest would be greatly appreciated!

virtualmix

#12
Dec 05, 2011, 02:20 am Last Edit: Dec 05, 2011, 02:50 am by virtualmix Reason: 1
Noobtoarduino, what you are trying to do is not that hard and you have already done a lot of work so far!

Don't be too impressed by the technical terms here, a switch is nothing but what you use to turn your light on/off.

Since you will be using an external power source, you want to be able to turn it on/off using a switch connected on the positive wire. Alternatively, you can also just unplug the DC adaptor from the wall to cut the power...

To fade the lamp, you will need a potentiometer, no rocket science, you can see many example on the web if you google it.

A heat sink is nothing but a piece of metal used to dissipate the heat away. Stick it on the back of the led (maybe with some thermal paste in between) and you're done. Also, the led description page doesn't say anything about using a heat sink so you may even don't need one. (Not sure, I never used this sort of led before... You may want to ask Sparkfun before.)

If you need a resistor, that would be to reduce the current to the led. How much current comes from the power supply? How much the led can take? Use a resistor to make sure you don't give too much current to your led. Use the formula I=V/R to calculate what resistor you need. If you need a resistor, you will have to connect it between the led (-) and the GND pin.

Hope this help :-)

Edit: Actually, it will get hot! (See this )

GoForSmoke

Go have a look in the playground. See how many different sense/control options you have and when you're done being amazed, think of which would be practical for your lamp. Remote control is good. Timing on/off/duration/brightness might be good. With capacitive sensing you could make a patch of wall that when you wave your hand past different ways it switches the light on or off, brighter or dimmer. You could have it come on when you enter the door, at least 2 different ways for less than the cost of the led.

Between the learning examples and the playground you not only get what can be done but how any why it works in pretty full explanations.


Nick Gammon on multitasking Arduinos:
1) http://gammon.com.au/blink
2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

Techone

That is an interesting LED... a powerfull one yes, but still a LED.  About LED's, you need two things :  Forward Current and Forward Voltage. That is the diode/led rule. THIS led is : 3.4 V @ 700 mA  Check the Power : 2.38 Watts  . Need a heatsink ? YES  to protect the expensive led.  To control it : use a power transitor / darlington type.  Check the Web : How to control a LED using a transistor.

Let say for example,  that I want to use in a 12 V lighting system. I will need : 1 K ( the base resistor ), TIP 31 , LuxLED, 13 ohms @ 6 Watt ( the limiting resistor ) , Heatsink - DIY type will do. ( for the LED, the transistor and the limiting resistor ). Make sure the PSU can supply at least 1.5 A.   My imaginary system use a car battery.  :smiley-mr-green:

My 2 cent. 

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