Picture of 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

Picture of 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.
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larsrc4 months ago
Exactly the instructable I was looking for, thank you. Connecting all three channels together vastly simplifies the design, but how nice is the colour? I got a simple set from a hardware store, and what they call "white" we all find has a horrible blue tone to it. I expect the different colour LEDs don't output the same amount of light, and/or our eyes don't register them equally.
Esterill (author)  larsrc4 months ago
Yes, you can get different 'colour temperature' LEDs. You want warm white to more closely match the look of incandescent lamps. My cool white LEDs don't suit everyone but give a crisper more clinical light for close work, cutting, preparation etc.
callhow5 months ago

Very attractive set-up & fully functional. Nice Job! I have a question ? Is there any

formula / chart to indicate how many "leds" will light - on varying voltages ? Like

how many using a 5 volt USB cable ?

hanashoib6 months ago

How do you have the cabling going across the sink and cooker? To power all three sets of lights?

Esterill (author)  hanashoib6 months ago
The previous lighting was mains and there is mains cable running between the two sections. I used that - it now carries the 12V.
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.

The RGB channels on these LEDs are actually the different colors of Red, Green and Blue. By tying them together, you get each color to illuminate at it's full brightness to produce the White color. By applying the voltages to the different channels, the illuminated color would change dramatically as the modulated voltage came up to full power.

Esterill (author)  PhantomOfHeat4 years ago
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.
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.
dxlrant3 years ago
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.
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

You are correct here. I have done some testing with white LED strips and have found that they work fine with adequate brightness at 9 volts even though rated for 12 volts.

Esterill (author)  dxlrant3 years ago
Hi, thanks for the interest. It may be sufficient but if the LEDs come on at all, they certainly won't be very bright.
bwomp991 year ago
Very awesome setup - I think I might try and play around with this, maybe use a tiny arduino or digispark so I don't have to build my own. Any chance you (or someone) could expand on step four? I'm not really understanding how the power is hooked up. When the power comes in from the brick, so you have it set up as a 12V rail and then just connect everything to that? Sorry, I'm pretty new at this.
mday82 years ago
Hi, is there any way that the LED strip fade out as well?
I want my leds to rurn on slowly and turn of slowly.

BAM52 years ago
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 BAM52 years ago
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.
atanguay2 years ago
Great Instructible Esterill...I'm trying to do something similar.

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


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.
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 (author)  atanguay2 years ago
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?
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)
jimthree2 years ago
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 (author)  jimthree2 years ago

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.
FLAN3 years ago
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 FLAN2 years ago
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!
I don' t think the Wattage makes any difference
samaddon FLAN2 years ago
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 (author)  FLAN3 years ago
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.
giftsocool2 years ago
I used the Warm White LED strips. It is also pretty good.
http://www.yupgift.com is my suppliers
instme3443 years ago
It is great, and my friend used the Warm White LED strips. It is also pretty good.
bennyj1213 years ago
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.
tmasse3 years ago
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?
fcross14 years ago
WOW !!!!
minnegopher4 years ago
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?

Esterill (author)  minnegopher4 years ago
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 frogy4 years ago
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 (author)  uncle frogy4 years ago
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.

pro2xy4 years ago
Sorry for a silly question, but what is power cycling?
Esterill (author)  pro2xy4 years ago
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.)
ken24004 years ago
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.
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