how do color change LEDs work?

How do the LEDs that fade colors work?  It's actually three lights, (red, green, and blue), right?  But what makes them fade on and off?

Posted by aliasjanedoe 8 years ago

Fade in fan

Hi! This might seem like an odd question but I need a fan to "fade in" for an art project I'm working on. That is I need a circuit that makes the fan spin up slowly to full revs. Is it possible to build some simple circuit that can manage this task? And if so is the case could someone please send me a plan for it? The fan is a standard CPU-fan (12V). Thanks for your support!

Posted by feldreich 8 years ago

teeny tiny circuit to make led fade in and out.

Good morning. long time lurker, first time poster. i am working on a small project and thought this would be the best place to ask. i need to come up with a teeny tiny circuit that when power is applied will fade in an led (over 1sec), and then when power is removed will fade back out (1sec). it doesnt have to be exactly 1 sec, but somewhere in that ballpark. the space i have to work with is only 21.91mm X 6.02mm X 19.4mm, and id like to also be able to add a small switch in there too so i can disable the led when its not needed. input voltage is 12v and i need 5.5v out, 6v max. any ideas are welcome. i have found a few circuits on here already, but most are way to big to fit into the tiny space i have to work with.

Posted by RelikL 1 year ago

PWM fade

I am using micro controller in a project that has a set of functions (API) that can be used for a plethora of things.. (just up to you to program it that way) LOLIt has a PWM control... which i am trying to use to FADE in (and out eventually) a high powered LED (LUX III to be specific).. the problem I having is that at a certain point (say at 50-60%) of full brightness I see a VISUAL jump in brightness.. Im trying to get it to be smooth the whole way through to 100%more or less the code is like:PWM = PWM+2which I then wait 10 mSecs and loop it again...I have tried to put in some conditional checking to check to see if the current level of PWM is at a certain threshold..and then only loop it again after a longer delay (say 300mSecs) or something..I tried to search.. ut Im not sure on how to get a CONSISTANTLY smooth fade...ot smooth to say 50-60%..then a visual jump in brightness and then smooth to 100%..any ideas or links on the subject are appreciated.Thanks

Posted by xl97 9 years ago

Fade LED on/off when powen on/off with strong LED in miniature space

I want to make a "magic" staff which will power on a strong (>100 lumen) LED under a crystal in the top of the staff. There will be a hidden switch somewhere and I want the LED to power up/down in approximately 1-2 seconds. The power source has to be relatively small batteries but big enough to power the LED for up to 30 minutes. I believe this can be done simply with just a capacitor and a resistor connected to the LED but since I'm a complete beginner, I'd like some advice. 1) How to connect parts together.  2) What parts to choose? I can calculate the timing from t = RC (or is it root of RC?) but there are soooo many to choose from. Probably the LED needs to be fully powered at 3 or 6V. Probably the resistor therefore needs to be 100-500 ohms? Probably the capacitor needs to be approx 2 - 20 mF? But it would be so much simpler if someone says: "Take these components - that will work". I guess choosing the batteries will be crucial for both size, voltage and current conciderations. But please note that I want the LED to be as strong as possible - flash light strength.  3) Is it possible to have a faster power down than power up (0,5 s rather than 2 s) without overcomplicating things (and crowding the space provided). The space is probably no more than an inch diameter (2-3 cm) cylindrical hole for a maximum of 3-4 inches (7-10 cm) length.  All help appreciated! 

Posted by The Mad mathematician 3 years ago

Easy LED fade on - hold - fade off circuit?

Is there an easy way to make an led fade on and then stay at a constant brightness then fades off when the circuit is broken?

Asked by tsdgen 8 years ago

Can I make a simple LED FADE OUT circuit ? Answered

What I want is jus FADE OUT and not fade-in. Just want my Car's Room lights to fade out as slowly as in 6 seconds. 12V Power Supply available.I guess this is possible by having a suitable cap in parallel with the Bulb.What should the cap be?

Asked by mayur.phadte 7 years ago

Fading an LED off, not on, just off?

I am trying to have a red LED fade off after it is switched on. I know I would need a capacitor, the question is, what value would be needed and would the cap be placed across + and - with the LED (and current limiting resistor) going from + to - as per usual if you see what I mean? Any suggestions would be greatly appreciated. Many thanks, kind regards

Asked by LED Maestro 5 years ago

Fading Led (leds) inside computer looking like heart beat.

Hi! First of all I want to apologize my English but its not my mothers language. So what I would like to do is add warm white led (leds) into my computer what would fade out and fade in like really slow pulse. How this could be done. I can do basic soldering and schematics but the easier the schematic is the better :) And as cheap as possible because I'm not that rich at the moment. I have googled this a bit but found so many different versions and also they all faded so fast and I want my led (leds) to fade slowly. And because the idea is to but them to my computer this project would be using either 5 or 12 volt source. Thanks for all who can help me! Make

Posted by Markomaani 8 years ago

Led fading aquarium? Answered

Hello, I have a fish tank, and it has a TL light above it. I made blue Led's above the fishtank. My idea was: - You get like from 8 AM. - 8 PM. the TL ligth (or some led's i have to make) - From 8PM-10PM the blue Led's - And then it all shuts off. - And then the cycle goes aroud. But the thing is, the TL is 220V and the leds are powered by a 8V AC powersupply, I made a diode bridge, so it all works, But my TL ligth will just shut off, becose it has a timer on it, And i have to turn on/off the blue leds myself. So, does anyone have an idea how to do this? maby some extra white led's so i can power it from 1 cicuit? Greetings. Ingmar (Im from Holland, don't mind my shitty english)

Asked by ingkiller 6 years ago

Sequential fading LEDs. Power / intensity loss by the end of the string. How to make all LEDs the same brightness?

Trying to build a sequential fade on when power is applied and fade off when power is removed LED circuit. I have problems with power loss by the end of the LED string.  The current layout has 4 LEDs that will fade on one at a time until all 4 LEDs are lit and then the fade off in reverse order. My original idea came from osgeld's No CPU / MCU led pulse-fade circuit.  Any ideas on how to keep the power to the LEDs consistent from the first to the last? The idea is not needing to program any chips. Once I/we have figured out how to complete this circuit as desired, I will post it as my first Instructable.

Asked by pinhead1984 7 years ago

Fade LEDs on and off when the power is switched on and off

Hi, I'm still a complete novice when it comes to electronics so I was wondering if anyone here would be able to help. I'm rigging up some LED lighting for my aquarium which is set to switch on and off with timers on the mains supply to the house. The timers switch on/off the power transformers which supply the LED lights. I would love to find a way so that when the power comes on the lights fade on and when it goes out they fade out, would be nice if it was a long fade too, maybe 15-30 minutes, ideally 30 mins to an hour. I am guessing there would have to be some pretty big capacitors involved to that would fill up, increasing the brightness as they goe, when the power comes on and slowly discharge as the power switches off. Another thing to note is that I am using 2 different LED systems. The blue LEDs are using standard LEDs that are sold in blocks (3 LEDs per block, I'm using 3 blocks, so 9 LEDs total) and are designed to run on 12v. I am currently running them on 6v as they are pretty bright, but if the circuity could have them fade over an hour I would like to put them up to the full 12v.  The white LEDs are 4 of 3w luexon star type LEDs that are running in serial. The system goes mains > 12v transformer > 3w LED Driver > LEDs. Here is a link to the driver I'm using I assume that the fade device would have to go between the driver and the LEDs? Thanks for any help you can give me. Darren

Posted by d77uk 7 years ago

led flash and fade. how?

Video of RavelightPicture of RavelightIm interested in building a product that utilises coloured LED lights with multiple flashing and fading patterns.I have pulled apart a few LED products and examined the PCB's and the components and have a general idea of what is going on, however it is all new to me, and im unsure of the possibilities that exist. For example, i didn't know you could get pcb's so small...Basically i need the power source to be the small button cell batteries (up to 6 if necessary, though 3 or 4 would be preferable). With at least 4 LEDs of different colours (RGB etc). A similar design to what I want to make is a flashing LED light stick like people use at raves that I found. It has a button that seems to simply complete a circuit momentarily, and pressing it down again and again, scrolls through its 9 different flashing patterns.I have seen various different LED toys that vary on this, but are basically the same idea.The thing that I don't understand (on top of a lot of other small things) is what is under the black blob on the PCB? Is this something like a 555 timer? an IC? And how are these programmed to give all the different patterns? is it a microchip?This thing cost me $3 from a shop. three dollars!! cheap as....this is what I want for my product. can anyone help me out to understand?I can post a picture up in the next couple of days if people can't understand what i'm talking about.Thanks

Posted by noi noi 10 years ago

Why do things fade?

I was just repainting a wall witch color had faded away. Why does color fade away ?

Asked by Quest for Questions 7 years ago

What is the easiest way to fade in and out/pulse leds?

Consists of 21 blue leds connected in parallel taken from one of those cheap toy lightsabers. Before disassembly, the leds were powered by an on/off switch and 3 AA batteries. All options considered - 555 PWM, PIC, or even descrete components. Finally, circuit to be powered from 5V-9V.

Asked by clint2880 9 years ago

*linear* PWM LED fade with arduino

Arduino comes with a simple program to make an LED fade on  or off, however, as far as I can tell, the apparent brightness of the LED does not change linearly with the wpm duty cycle. After some research I found that this is because humans percieve brightness logarithmicly, not linearly. (Also, LEDs don't change brightness linearly with current, but sisnce I'm using PWM, i don't think that comes in to effect.) I found a simple look-up table to correct for this on this page. 255, 180, 128, 90, 64, 45, 32, 23, 16, 12, 8, 6, 4, 3, 2, 1,0 This seems to work very well, but I don't know where this comes from. Does anyong know the ectual equation to get the % duty cycle from the %brightness? I like to abstractise things.

Posted by Vick Jr 7 years ago

I am looking for a fade in/out useing a LED and 555 timer.?

Not sure what else i can say but I would like a scamatic of it..

Asked by dociledragons 9 years ago

combining blink and fade programs.? Answered

I tried creating a sketch by combining the blink and the fade programs, and it seem to work.I t either The blink works just fine but the fade takes a really long time to fade. is there a problem with the delay command.

Asked by carlos-leal 1 year ago

Arduino noob, need help

Hey ive recently jumped into the wide world of arduino. well i only did because i required the easy way out of led fading using arduino programming however i wish to use the Basics>fade example but using all 6pwm outputs!! can anyone simply modify this for me :) cheers

Posted by Applecore807 7 years ago

How do I make 3 LEDs alternately fade for a night light? Answered

I'm trying to make a night light for my little sister and thought it would be cool if I could make the leds fade alternatively. basically  the red would get bright and then dim and then the green would get bright and then dim and lastly the blue would get bright and then dim and then the cycle would start again. I found some code that allows me to brighten and dim a single LED but I couldn't figure out how to alternate three of them. Could you help me please : )

Asked by inconceivable1 1 year ago

Arduino Toy with LED indicator; LED, off, no use for 1hr; LED, fades in/out, after 20min; BLinks to button

Sorry about the question title.  Long time listener first time caller.  I'm developing a toy for my nephew.  He's really into lit objects.  So I'm trying to write this code in arduino for a basic toy. My nephew doesn't talk much and I thought maybe this would be a great way of him telling us how he feels.  So I'm thinking of creating a basic LED-based indicator.  I was going to connect 3 buttons to LEDS: red, yellow, and green. Dependent on how he feels, he would press the buttons.  But due to being a kid, his attention span is very short.  To keep him engaged I was thinking about adapting the "screensaver mode" and having the toy use minimal batt power and pulse peacefully in and out.   IF he's not around, i just wanted it to turn off by itself. Then any one of the buttons would be a failsafe to turn it back on again.   I'm new to arduino and would love to hear of any suggestions, recommendations, hatemail, chain letters, anything that would elucidate coding.   I would really appreciate it.  Thank you so much. Grateful, R   

Asked by RobotTree 7 years ago

How to create an adjustable fade in/fade out circuit for 27 LEDs?

Https:// I would like some input on creating this using POTs to create an adjustable fade in/ fade out effect on the 27 LEDs while running on a 9v battery if possible.

Asked by YoungOne453 4 years ago

How analogWrite will fade an LED? Answered

Since analogWrite is used to fade an LED.But the LED positive pin is connected in Digital pin of Arduino.How a digital pin will perform analogWrite function.

Asked by Rajkumar2506 1 year ago

fading on a picture quilt?

My daughter received a quilt with beutiful pictures of her on it she spilt water on it and i noticed the color on pictures faded away,, i realize i might not b able to fix that but my question is wat is the tenique for printing pics on fabric and not having them fade

Asked by tula4 8 years ago

How do I fade dark blue jeans?

I have purchased a couple of pairs of dark jeans. Is there any way to expedite the fading process?

Asked by 8 years ago

Fading LED Circuit

GOAL- My goal is to light up a small model I have using an LED circuit that will automatically fade in and out. DESCRIPTION - I will be using 19 blue LEDs (3-3.2V fwd voltage, 20mA fwd current) and would like them to fade in and out on their own very slowly. I am thinking that this will be powered using a phone charger or other household transformer since batteries don't seem to be a feasible option for this (too many batteries clustered together and/or too short a life span). I have a transformer on hand that runs 5 volts at up to 850mA, so if that works then perfect, if not then I could try to find another transformer. For the sake of simplicity I could add one more LED to make it an even 20, though I would have to drill another hole in my model. TASK - I need the circuit to make these LEDs do their fading. Simple as that. Fading circuits are easy to find on the internet, but I have been having trouble finding anything to meet my project criteria. Any help with this would be immensely appreciated!

Posted by Andrew Wiggin 4 years ago


Hi ive attached a led to a couple of rechargeable batteries it begins with a bright light and starts fading and then reach a point where it doesn't fade out any more and stay like that for days. what shall i do to make the illumination of the led constant? P.S. No capacitors were used

Asked by electrod 8 years ago

layout.png on Fade? Answered

It appears that the layout.png file tab on the fade example is wrong. Am I misinterpreting this? I had my board one way that worked, then tried to copy the example in the layout.png tab and it didn't work. I'm loving the class by the way. Cheers.

Asked by blakellarson 1 year ago

How do you make 2 LED's fade (PWM) consecutively on an Arduino? Answered

I want 2 LED's to fade one after another but i can't figure out the code yet. 

Asked by Density 5 years ago

How do I make a RGB leg fade between colors using a arduino?

I would like to make a RGB led that fades inbetween colors how do I do that? Do I just do the fade code 3 times but just put in the 3 different ports in which the different color thing are in? Also do I make 3 different fade circuits from the arduino site?

Asked by landsharkxx 5 years ago

Getting an LED to fade on and off

I plan on making an LED sign and I would it to fade on and off continuously. How would I go about doing that?? I don't have much experience with electronics so pardon my ignorance.

Posted by Mr. TiKi 10 years ago

Dim an LED with DMX and Arduino

I need to control a single LED strip from a DMX lighting desk. I'm planning on using an Arduino with a MOSFET and use the analogWrite function to control the brightness (possibly with some capacitors to smooth the dimming process). I want to be able to transfer the 8-bit value from the DMX channel to the 8-bit analogWrite Arduino function. Any tips greatly appreciated as I've struggled to find any tutorials dealing with only one channel and an issue as simple as this. Thanks. UPDATE: I eventually just used an RGB LED strip DMX decoder and used the three different channels for three different LED strips. The project that steveastrouk posted below is now available at: I eventually just used an RGB LED strip DMX decoder and used the three different channels for three different LED strips. If I figure a way of doing this with an Arduio, I'll post it here.

Asked by theredbryophyte 2 years ago

Help with LED combination to make a face.

Hi,      I am trying to make a face using LEDs.  I have attached an image of what I want to make.  Referring to the image the first set of Led will fade in one by one and then stays on while the next set of LEDs fade in one by one.  This will continue until all the sets for the mouth LEDs have been faded in.  Then the eyes, white LEDs in the outer and yellow LEDs in the center, both will fade in together.  After everything has been on for afew seconds then they will fade out in the reverse direction of fade in.  I would appreciate any help or suggestions as to how to tackle this project.  Thank you

Asked by pepelpue00 2 years ago

LEDs Fade In/Out Circuit Problem and LED Sequencer Problem

I built this circuit from the led beating heart frame instructable. I can't seem to get it to work. Any ideas? I also built this led sequencer. It doesnt work either. please help.

Asked by madman11 8 years ago

How Do I Make LED's Fade with an already build flashing circuit? Answered

Hello everyone! In my spare time I've built a simple circuit which makes an LED flash. The flashing is controllable through a Potentiometer. I have attached a circuit diagram (made really fast, so i know it's bad) and the picture of the breadboard. Now, my question is: How can I make the LED fade on and off instead of flashing? I've tried to hook up a transistor but i've not succeeded. If everyone could help, I'd appreciate it. Here is the stuff I think could be useful that I have avilewable: Some BC 144 Transistors (I suppose they're PNP) Some PN 2222a Transistors 220uF Cap, 100uF Cap and a 10uF Capacitor. A lot of resistors. I do have more components but I don't think they could be used for this project. And excuse me for any mistakes, English is not my Language, Thank you!

Asked by Reogen 9 months ago

Can i make a LED to fade with music?

I want to have a LED alwais on and with the tempo of the music the LED will turn off or fade. to make this i have a npn a pnp and a SINGLE OPERATIONAL AMPLIFIER the led is 3v. i don't have an Arduino o another tipe or controller

Asked by clowreed 4 years ago

Modify LED fade in/out circuit?

I am building this circuit is the breadboard of it. This works, so if the schematic is different, use this instead. want to modify it so that is uses a 5v power source. What resistor should I change and how many ohms shuld the new one be?I also want to add a potentiometer so I can change the fade in/out speed. What resitor should I put it in place of?Thanks for the help.

Asked by madman11 8 years ago

what is the capacitor code?

I have a green capacitor that has the code, .22k 100sc What is the value in uf?

Asked by madman11 8 years ago

How to fade a led in over 10 minutes, using cheap ic's? Answered

I want to fade in 4 leds over a period of 10 minutes then have then turn off after another 50 minutes or so, voltages of leds dont matter. Any ideas would be great! Thanks Cybot

Asked by Cybot Rules 9 years ago

Nobody has talked about this point (that I could find). Does this homemade laundry soap fade your colored clothing?

The reason I ask because I stopped buying the 'cheap' detergent long ago because it faded my colored clothing. I know there is commercials dedicated to this; "wash after wash, the clothes still look new and the color hasn't faded!" Can anyone noticed that their dark clothes are faded and they have worn out quicker????????? This is the only reason I am afraid to try this money saving tip!! thanks :}?

Asked by 9 years ago

Analog Fading LED

Hello - I am brand new to electronics but am trying to learn about BEAM and other art + science circuits. I am looking to make a small analog circuit to fade in and out a LED. I have looked online but have found a bunch of ones using a 555 timer or a PWM and other chips. I saw a reference to doing this slow fade in and out technique using only capacitors and resistors but have been unable to find a diagram. Can someone help me out. FWIW - I am looking to charge this using solar and am only looking to drive one LED. Ideally a days charge would last a few hours of fade in and out cycling with the cycle time being slow - somewhat like the Mac "Sleeping" LED. Thank you in advance.

Posted by toddbg 10 years ago

How to UV-modify the "USB fading star" instructable?

I have built sooraj619's "USB fading star"  circuit (, but with UV LED's instead of red. I hadn't thought about the fact that red LED's have a quite low voltage need (about 1,8-2 volts) compared to UV LED's (3.2v – 3.8v). But it is a problem. The UV LED's (24 pcs) aren't even close to full light intensity. They do, on the other hand, pulse in the right slow way. Does anyone know in which way the circuit could be changed to make the LED's light up properly without the LED pulsing being all disturbed? The circuit input voltage should remain 9 volts though.

Asked by J.W.N.R. 6 years ago

How to take good pictures in fading light 'ible request

Here in England the light fades fast and i cant take instructable photos after about 5:30 pm because they look dark and crappy. Does anyone know of a cheap way to replicate natural-ish light, like a soft glow not a big glare Thanks :P (like the picture below, its too dark)

Posted by =SMART= 9 years ago

I was trying to modify code for fading LED. ? Answered

I modified code for fading LED. I want to go from brightness 0 to maximum and NOT in reverse order. code is below. With this code , LED brightness just led = 9; // the PWM pin the LED is attached toint brightness = 0; // how bright the LED isint fadeAmount = 5; // how many points to fade the LED by// the setup routine runs once when you press reset:void setup() { // declare pin 9 to be an output: pinMode(led, OUTPUT);}// the loop routine runs over and over again forever:void loop() { analogWrite(led, brightness);for( ; brightness brightness = brightness + fadeAmount;

Asked by dauly 1 year ago

How to make a "Timed" LED Color Sequencer ?

I would like a "timed" LED Color Sequencer. So instead of a board that flips between leds or strobes I want it to stay in a color for a couple of minutes. Ex: green for 3mins, then fade to red for 3mins, then fade to blue for 3mins then fade back to green.. Time as 3mins is just a example but must be for a longer period then just a fade and longer then just a couple of sec. It must be driven with small batteries, must be driven on its own so no interference of people as a touchpad to switch/fade.How would one do such a idea, do I need to have a microproc or can I skip that ?

Asked by captm99 6 years ago

LED Circuit Help

Https:// I would like some input on making this using a 555 timer and POTs to make an adjustable fade in/fade out circuit while running on a 9v battery and using a pressure switch to turn the LEDs on when the box is opened.

Posted by YoungOne453 4 years ago

LCD contrast issue?

Just got a LCD 20X4 character screen. 10K pot connected to 5V. Can controll contrast. problem is, only 1/2 of it???"--------------FADED----------------""--------------DARK------------------""--------------FADED----------------""--------------DARK------------------"only 2/4 rows of character blocks go dark when full contrast. why is this!!!

Posted by Killa-X 10 years ago

LG monitor has faded picture and then goes black

Hi, I’m experiencing problems with my LG Flatron Wide. The screen comes on with a very faded picture and then goes black. I assumed that maybe the capacitors (like for others) needed to be changed. However, I have opened the monitor and the caps look perfectly fine, no bulges or anything. Does anyone think I should just go ahead and try changing the caps anyway? Or could anything else be wrong? Thanks a lot.

Posted by Chu Guk 6 years ago