How to fit LED kitchen lights with fade effect

In this instructable, I will describe my project to replace my under the cabinet kitchen lights with LEDs.  I couldn't resist adding a microcontroller as well.

The original lights were flourescent and quite badly fitted.  They made a lot of buzzing noise and the bulbs didn't seem to last very long.  I got fed up with them and decided that replacing them with LEDs was the way to go.  My budget was small so I didn't want to buy expensive designer lights.

To add interest and a bit of practicality, I decided to add a fade-up effect when the lights switch on and have a half-bright mode for those special occasions where dimmer lighting is required.

Step 1: LEDs

After experimenting with some cheap LED strips meant for accent lighting on cars, I did some 'proper' research and settled on the flexible strips of SMD 5050 LEDs.  This is an excellent page describing the 5050's vs the 3528 type: http://ezinearticles.com/?All-About-LED-Strips-4---The-Eternal-Debate---SMD3528-Vs-SMD5050&id=4670120 .

You want 5050 LEDs, preferably 3 to each 5cm / 60 per Meter, waterproof (they are covered in a flexible clear plastic and with a adhesive backing.

I got a 5M strip plus power supply from a seller on eBay.  Total cost was UKP 50.00.  

The LED strips can be cut every 5cm (or 3 LEDs) and are very bright.  5M of LEDs consumes approx 3A (36W at 12V).  This is less than the 4 flourescent strips they are replacing.

Comments

[BAM5]

RGB Strips are actually for creating any colored light you want. It works on the same principal as the individual pixels in your computer monitor. In each pixel there is a red, green, and blue part of the pixel that are individually controlled to output different strengths (Up to 255 different levels of strength) of each color in order to make practically any (16 million different) color in the visible spectrum. In order to do this on the RGB strips all you'd do is set up a separate PWM signal to each of the channels (R, G, and B are the different channels of the led) and change the duty cycle to change the brightness of each. In order to design a color you can use a color picker on a computer. The colors from the color picker are generally written in hex, with the red channel being the first 2 digits, green, the next 2, and blue the last 2. So #FF0000 would be full red, #00FF00 would be green, and #888888 (half duty cycle on all channels) would be grey (on the computer) or a dimmer white on the leds.

tl;dr: Bleh, that went into a whole long rant. RGB leds are for creating any color you want. Not just white, red, green, or blue.

[BAM5]

Correction #7F7F7F would be half duty cycle/grey/Half dimmed. Side note: There are bussed ic chips for powering/controlling leds with PWM called led drivers. TI makes a large selection of these.

[atanguay]

Great Instructible Esterill...I'm trying to do something similar.

Quick question, any idea why this MOSFET wouldn't work in this scenario...

http://www.futurlec.com/Transistors/IRF510.shtml

These are ones they stock at the local 'Shack, and it seemed capable, but some of the specs I don't really understand. Any thoughts?

I'm using a 12V strip, just like you...powered by an old 'Xbox HD-DVD' power brick, on a regular Arduino, programmed to Pin 9.

[atanguay]

It all came down to grounding!

I wasn't grounding my Arduino and my PS together. Once I did that, I am in business and fading. Now I just need to try and get the first couple of levels to not look so 'steppy' and more smooth and I'll be golden.

[Esterill]

I had a quick look at the spec sheets - I can't see an immediate reason that the IRF510 wouldn't work. It can handle the current and voltage required. What are the symptoms? Have you tried just having the FET switched on (no PWM) or tried a different load?

[atanguay]

Basically, the strip lights up full time, even when the transistor is 'off'. That's what threw me immediately. I was getting 'some' dimming, but nowhere near the full range I'm getting with just an LED. I went and picked up a couple more...maybe this one is bad or dead or something. Although it seems strange that the thing would be 'ON' full time when dead. You'd think it would be a 'dead mans switch' scenario.

(thanks for the ideas and replying, btw. I really want to get this to work)

[jimthree]

Do you use "Arduino" the Mega168, or are you building native atmel Hex files? I thought you needed the !68 to be running with a crystal rather than the internal timer to use Arduino on it?

Cheers Jim.

[Esterill]

Jim,

I used the Arduino environment. You can use the 168 with an internal oscillator but you need to remember to take into account that it is running at half of the speed Arduino expects. I edited the devices file to add an internally clocked 168 so that it would all make sense.

[FLAN]

I have a question.. I bouhgt this SMD leds and I want to use a power supply 12v 65w, I conect it and LED light up, but the strip is getting to hot, This is normal?

[samaddon]

you need to decrease the voltage to 11 volts and 35w if you are using a single led then after some time the led will blow up!

[diy_bloke]

I don' t think the Wattage makes any difference

[samaddon]

you need to decrease the voltage to 11 volts and 35w if you are using a single led then after some time the led will blow up!

[Esterill]

Hi, It depends on what you mean by 'too hot'. All LEDs get warm or hot when on. Because there are a lot of quite high power LEDs on the strip, we would expect some heat. Once the strip is fixed to a surface be it metal, wood etc. I would expect the heat to be reduced. However, if you are worried about the level of heat you should contact the supplier for advice.

[giftsocool]

I used the Warm White LED strips. It is also pretty good.
http://www.yupgift.com is my suppliers

[instme344]

It is great, and my friend used the Warm White LED strips. It is also pretty good.

[bennyj121]

I have pretty much the same setup and used an old iomega supply ffrom an old drive. It has a 12v output at 2.5A and another 5.1v output that does not light up my 9 foot string. I am not sure which SMD LED's my strip has, but I thought I would do the dim thing the easy way but they will not loght at such a low voltage. I hacked the microwave and used the built in lights on it to power the iomega, so when i turn the microwave/counter lights on, my cabinet strips also power on. The 'dimmer' switch I added (to the 5.1v line) acts as an off switch now.

[dxlrant]

In your testing environment with the segment of 3 LEDs would 5 volt be sufficient to power all? I realize the strip is rated for 12 volts, but just wondering.

[PyroMonger]

you can use 9volts and it will work fine. I have blue strips like the ones used here and they run on a 9volt battery with more than adequate brightness

[Esterill]

Hi, thanks for the interest. It may be sufficient but if the LEDs come on at all, they certainly won't be very bright.

[tmasse]

Very nice job.
I know it would be messy to implement without parting with PWM, but couldn't you use some sort of capacitor so to have a fade-out effect when turning the power off?

[Topcat2021]

That is a very nice setup you have and I love the fade in feature. I may have to try this for myself.
Again Great Job keep up the good work
Dan

[fcross1]

WOW !!!!

[minnegopher]

Awesome project! Nice work!
* could you provide a parts list to go with the schematic?
* did you connect the LED strip(s) to ATMEGA168 pin5, or where?

thanks!

[Esterill]

Thanks for your kind comments.

I did neglect to properly list parts so here you go:

Processor is an ATMEGA168 in DIP package, although almost any AVR will do.
D2 is a regular LED on the board for a heartbeat indicator. It is optional as is
the 1K resistor.
H1 is a 'standard' AVR ISP programming header with 6 pins. You only need this if you are going to do In System Programming.
U1 is the MOSFET - a STP16NF06
U3 is a 5V regulator - LM05
D1 is actually the LED strip - obviously, there are a lot more diodes! It is connected to pin 5 of the processor via the MOSFET.
The other Rs and Cs are labelled.

[uncle frogy]

I recognize that I am at times parsimonious I can't help it.
So here it is how much current does the controller use and how does that contribute to the overall efficiency compared to just a pot as a dimer? I do appreciate doing the work and fun of doing the controller and how you can get "more light" from a LED by pulsing the voltage over just DC . just wondering . I just like to keep it simple.
I also think that some of the heat seen from those strips comes from the current limiting SM resistors that are on the strips.
Color is very important to how we see food next time you go to the supper market look at what color is in the meat and the produce departments they are not blue. think more along the lines to art and the need to have color accuracy. Same goes for the bathroom think what the lighting difference is between the bathroom in a high class restaurant and a serve-yourself gas-station. no woman is going to feel comfortable in a blueish lighted bathroom
great project and well executed.
uncle frogy

[Esterill]

Hi and thanks for your comments. The controller is an Atmel AVR. Current consumption is in the order of a few mA, so it is utterly insignificant compared to the current consumption of the LEDs. The advantage of using a microcontroller is the programmability and the cost - I can adjust the fade effect as much as I like until it is right and all for a cost of about 1 pound in components.

I don't have the analogue electronics design skills to produce an LED fader with a pot and most LED related controllers seem to use PWM - it is cheap and effective.

I agree on the colour - I tried a warm white LED but my wife didn't like the look. This colour suits us fine. Remember the rest of the room is lit differently and the camera is showing more blue than our eyes actually see.

[pro2xy]

Sorry for a silly question, but what is power cycling?

[Esterill]

It's just a phrase meaning turning the power off and then on again (usually with a pause between to allow capacitances to discharge etc.)

[ken2400]

http://www.candlepowerforums.com/vb/forumdisplay.php?f=89
Start reading.

Heat is still a big problem with store bought LEDs BUT DIY ones can be made with all the heat sink they need. I hope someday they will product less heat and more usable light.

[belcat]

These LEDs actually produce more heat than the ones you buy in the store as bulbs (they are less efficient). But wait, you say, why don't need a heat sink? Because each LED doesn't use a lot of power, so basically, the long strips they are on act as a heat sink, and the heat is distributed all over the strip.
The problem with store bough LEDs are they are trying to fit in old style bulbs, a tight space where you can only put a little bit.
The real problem is the lack of manufacturing, demand and competition. The LEDs are $3-5, the heat sink is $3-4, the driver is about $3. That's $12 at most, the rest is just markup because they are the new kids on the block.

[devin.buell]

The LEDs don't actually generate a lot of heat, that is why they are so efficient. The heat sinks insure that heat doesn't build up and effect the operation of the LED's.

[Esterill]

These LED strips don't really generate much heat - it is true that what is generated is dissipated across their length and, to a certain extent, into whatever they are stuck to. If heat was a major problem, I would expect the sticky backing would fail pretty quickly. That hasn't happened yet.

[PhantomOfHeat]

If the RGB is hooked up to separate leds It seems like you could use that for fading by starting the R then having a delay before starting the G than a delay before the B that will add more of a fading effect.

[Esterill]

Yes, that is a good idea. I would like to have done that but the existing wiring only allowed one channel. Perhaps with a controller on each set of LEDs, I could achieve this. Too expensive (in time) at the moment though.

[PhantomOfHeat]

I was not sure if you could have programmed the chip to drive 3 mofsets individually. Alternatively you might be able to use a zener diode (do not think that will work with PWM) or something that will allow the first mofset to turn on once the volts hits the knee it allows the second one to turn on and does the same with the third.

[alts63]

If finding and connecting isn't your thing:Ikea has several LED lighting strips, some in different colours. Don't know if this is cheaper than sourcing the parts but got me started. Thanks for showing us how to DIY.
http://www.ikea.com/ca/en/catalog/products/20119418 or
http://www.ikea.com/ca/en/catalog/products/60180767
Love the dimmer idea.

[Esterill]

I used some Ikea strips in the bedroom - I may replace them eventually with colour changing strips. They cost quite a bit more than the equivalent RGB or White LED strip I used.

[gmabe1983]

anyway to see the light output in lumens?

[Esterill]

I expect I would need some kind of light meter. My guide was 'can I see well enough to prepare food?'.

[jsil]

Hi Esterill, thanks for the very good project. What do you have for ceiling or central lights ? Or in better words, do you use other lights in the kitchen, (because the led lights are focused to especific regions) ?