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

[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?

[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.

[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) ?

[Esterill]

Hi, Thanks for your comment. Yes, I have other lights in the kitchen. I have 6x GU10 halogen spots for the main lighting, a net of white LEDs hanging on the wall opposite the cabinets for accent lighting' and a plain old ceiling pendant light for extra lighting at the far end of the kitchen. I am replacing the GU10 halogens with these: http://www.simplyled.co.uk/GU10-High-Power-LED-20-piece-SMD-5050-320-Lumens-50-watts-equiv_ASI5T.aspx?0 mainly to save electricity.

[kevinhannan]

I thought this could be used for a fish tank lighting to mimic the daylight hours and provide a soft start and end rather than 'shocking' the fish with instant light on and off - my fish go nuts for a few seconds when that happens. It's a nice project for a few apps I think - thanks for sharing!

[rswander]

This application can be used, with great relief, in bathroom lighting. There is nothing like the shock of bright lights in the wee morning hours!

[kyle.marsh]

From what I understand the human body's sensory response to *most* things (sound and light, at least) is logarithmic. The way it was explained to me, this is how our eyes can have such a high "dyanmic range"...if you're in a dark room with a bright window you can see things in the room more or less at the same time as you see what's out the window. A camera in the same situation would be able to see either the room or the outside but not both at once.

Anyway, the point is you can probably get a more linear feel to the brightness by bringing them up to full brightness with an equation along these lines:

 B = ln(1+t) 

Where B is the brightness, ln is the natural logarithm function, and t is the time since you first turned on the lights. I put 1+t because the logarithm function reaches 0 at x=1 and then drops into the negative. You may have to play around with scaling on both axes but it should be a good start.

[Esterill]

Thanks for all the comments everyone. A few thoughts:

The main aim of the project was to replace the kitchen lights. The fade effect was a nice addition and one which I wanted to do myself to learn more about using MOSFETs and PWM. My next project is also LED based and I've learnt plenty from doing this. I was tempted to use RGB strip and have 3 channels of fading but in the end, I didn't want colours in the kitchen so they would have been a waste of money. The bright bluish white isn't to everyone's taste and, of course, you can buy 'warm white' LED strip or go to RGB and mix your own - I'd like to see how that looks (hint hint). I had looked at the commercially available controllers but rejected them because I couldn't be sure they would be able to do the automatic fade up when the power was applied.

[Corrugator Supercilii]

Such a wast of effort doing the microcontroller... You can eBay a PWM controller meant for these RGB LED strips (with R, G, B, Cathode connections), it even comes with an IR remote control.

[Oldbear]

Sometimes the "waste of effort" is fun and can be a learning experience. Many of my projects are available at a local store or ebay... but then I couldn't say "I built that..."

I have a friend that built a stereo sound card in the early 90s. You could buy them, but why (or so he said). He then went on to build sensors and automation for his chicken barns. He then went on to build them for others... now he doesn't have to chicken farm any more. You never know where a "hobby" can lead.

That said, it is good to know that I could get the controller from ebay, as my soldering skills are still lacking.

[Corrugator Supercilii]

I didn't meant to say 'it's a dummy thing to do, duh!' More to point out a quicker and easier way to do it.

See the link for the controller on eBay, runs off any adequate 12V power supply.

The 5050 package packs 3 LEDs, hence either a RGB or 3 white LEDs. Was going to use these strips for Red Blue grow lighting for plants,

http://shop.ebay.com/?_from=R40&_trksid=p5197.m570.l1313&_nkw=IR+controller+for+RGB+strip&_sacat=See-All-Categories

[Oldbear]

Oh. OK. I will just buy a controller from ebay. I weld metal and make things out of wood... but soldering results in melted boards and burnt fingers...

[wetnap]

The problem is that you need to find a light with a decent color temperature, and the cheapest accent car lights aren't going to be bothered witha nything more than the cheapest lowest tech leds out there. No good for home lighting. Nicer more efficient leds are out there from cree and luxeon, and don't cost that much as raw components, and you can choose exact color temperature. various flashlight forums like candle power probably have a lot more expertise on this. you can easily order the cutting edge leds out there for not that much, but they don't show up in consumer products until years later.

[johndimo]

I love this. I'm going to make this as well. I love the look of under cabinet lights.

[jptrsn]

It would be nice to have included an option to change the colour via the RGB PWMs - you've already got the microcontroller set up! Maybe a "night mode" where it runs a very dim red, or something. Neat idea, and well done too!

[blddk]

I think that if I was to make something like this, I would use all three channels, that way you can make it a disco and change colors. But also make it a more warm white than the white with a tad too much blue in. More comfortable to look at warm white for a longer time, imo. :)