Fuzzy Logic Mood Light With LEDs




In this instructable i will make a red mood light out of stuff i had using things i found around the house.

After a particularly long, awkward night entertaining company i found myself in need of a low wattage light source of the romantic inclination. Without one i found myself in the dark and was reminded of Woody Allen's character In Annie Hall.

" Hang in there for a second. I got a
little-little artifact. A little erotic
artifact, that-that I brought up from the
city, which I think, uh, is gonna be perfect. "

The artifact in question was a red light bulb, I think i can do better. Lets get started


Step 1: Make a Base

I found a chunk of sign foam and cut it into a square. Sign foam is a high density urethane foam thats light, easy to work with, waterproof, unaffected by moisture and non conductive. I always find scraps around my house, as should you.

I used a small hacksaw to rough out the shape and 80 grit sandpaper to smooth out the edges. I went with a more organic shape because i didn't want to take the time to get all the edges square. im lazy that way.

Step 2: Making Holes

Next i marked up twenty five spots on the foam where i wanted the leds to go. I happened to have 25 diffused red 5mm blinking leds left over from making throwies. I wish i had red/blue or reg/green flashing 5mm leds for style, but all red makes up for it in pure machismo.

I made sure to lay out the 5x5 grid pattern in no particular order because i knew id never be able to properly line everything up without measuring. And measuring was imposable since i sanded off all the straight edges. So i just picked 4 spots and eyeballed the middle points till i had 25 dots marked out.

Cheap 5mm chinese leds are just a little smaller then my cheap 13/64 drill bits from harbor freight. So i used that drill bit to bore a hole at each dot. Not wanting to put holes in my patio furniture i used an old box as a base. I tried to drill straight up and down, but some of the holes are at odd angles. Meh

Now most of the LED housing fits into the hole, but the flange at the base of the diode body keeps it from going all the way in. Using a piece of scrap foam and a 1/4 inch bit i test the depth before counter sinking all 25 holes. Id hate to ruin this one now that ive spent so much time on it.

Finding the depth acceptable i mark it with electrical tape and proceed to countersink all 25 holes so the leds just barely peek out when installed. I like the look of proper led mounts, but for projects like this the cost is just to high for that "professional" look. Check ebay for prices, in bulk good mounts are rather reasonable.

After blowing all the dust out its time for a quick test fit to make sure all the LED's seat properly; then its on to painting.

Step 3: Painting

Painting is easy, i just make it look hard.

Raw sign foam is porous stuff and just sucks up paint while the panel parts paint beautifully. First its two coats of black primer, then 2 coats of red enamel. Then colour sanding and another coat of red. Finally for that "wet look" i hit it up with a coat of clear acrylic. The clear takes forever to dry and 2 hrs later i left a bunch of fingerprints in it. This required ANOTHER coat of clear and an over night cure just to be safe. The end result is candy apple red on top with a slightly less shiny effect on the sides. Since i only plan on turning it on when the other lights are off, this is of little consequence.

While im waiting for the paint to dry, i decided to test out the leds.

Step 4: LED Burn in Testing

Since my leds have a super wide voltage range and some built in resistors anyways i decided to use a 6v 650ma wall wort with no other electric components to power this lamp. Im not adding any additional resistors because im lazy, but i dont want to burn the house down ether. The simple solution was to drop all the leds in a breadboard and plug them in just to see what happens.

This is a video:

In theory everything about this is wrong, the voltage is to high and there isn't enough current from the transformer. If i remember highschool physics correctly this should rip a hole in space/time within the first 5 minutes. Sadly, after 2 hrs the leds are only slightly warm.

Step 5: Soldering

The first thing i did was make sure all the leds were in the holes properly, with all the little legs in one direction and all the long ones the other way. then i flipped the piece over and checked to make sure none of them weren't sticking out to far (or not enough). While im sure no one else will ever notice (or care), it would bother me forever.

Next i cut some 20g uninsulated soft copper wire into sections long enough to connect all the legs in one row. I just laid the wire next to the positive leads and added a drop of solder to make them stick. Copper wire loves being a support in my electronics projects as its easy to work with and takes solder easily. I soldered all the positive legs together in one row, then all the negative ones, making sure to leave a little extra wire hanging off the side. I checked each row as i finished to make sure (one last time) that there were no bad LEDs. I actually found one that got heat damaged from the soldering and needed to be replaced. Its a lot easier to do this now then later, so check often. That extra bit of copper off the end is used to connect all the rows so the 25 LEDs are essentially all connected to the power supply directly.

Some people would call this parallel, i would call those people nerds. Normally im all about wiring LED's in series, but because these are >blinking< diodes they need to be treated differently. If you add anything after the blinking led in series, that extra component will only get power when the blinking LED is on. I have used this to my advantage in other projects, using the blinking led as a cheap/easy timer, but here i wanted each light to blink independent of all the others. So parallel is a must.

At some point i clipped the barrel plug off the wall wart and stripped the insulation off the wires. These bare ends i now solder to the leds. Because the diodes are all in parallel i could solder these power lines anywhere and the unit would function. After plugging it in to the wall everything worked great.

Heres a video:

The last thing to do is clip all those unsightly legs from the back and put it someplace where a red light is needed.

Step 6: Final Thoughts

In retrospect 25 blinking red LEDs is not as romantic as I had first envisioned. At best it projects a warm, slowly moving red light on the wall akin to a dying fire. At worst it looks like some old tymey computer. Depending on your company this might be sexy, but everyone will know your a nerd.

The really cool part of working with lots of blinking leds is the realization that none of them work on the same timer. Low quality standards during manufacture means slight differences in each led, no two are alike. Put three together and they chase each other endlessly one way then the other. Add more and other patterns seem to emerge and fade away all by them selfs. This means sudo random effects can be accomplished without complicated micro controllers or programing skills. Impress your friends, people inherently want to believe order is present where none exists.

*EDIT* Feb 27

By popular demand i took some extra photos of the finished product.
And an extra video:

Eat your heart out kids.

*edit* July 21

Existence is random.
Has no pattern save what we imagine after staring at it for too long.
No meaning save what we choose to impose.



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    55 Discussions


    10 years ago on Step 4

    If the Ac adaptator is not able to send enough current, it mean that it will : -Over heat a little (and may became hot during summer days) -Not be able to send as much tension (volts) as it should -Will not be able to send a constant tension (it will vary a little bit with the same period as your AC source, 50 or 60Hz) The two last points explains why you leds do not over heat to much (did you try to read the real tension with a voltmeter ?), but there are certainly better way of doind things, like : -Add a voltage regulator before the leds -Add a non blinking led in serie with each the blinking led, hence double the voltage drop (but you'd have to check the specs of the integrated resistor in the leds to see if the voltage drop is not too strong) -Add a resistor (cost about $0.15 !) Anyway, the leds will age faster, but it is not a real problem. Just remmeber to check the temperatur of the AC adaptator from time to time after long use in hot days just to be sure.

    3 replies

    Reply 10 years ago on Step 4

    Wow, thats a mouthful. And while you are most likely right on several counts, my unflinching laziness makes me not want to do anything at all at this point. A few months back i snipped the wall wort leads and added a 9v battery clip for portability.


    Reply 5 years ago on Introduction

    My electronics knowledge consists of "find an instructable, watch how they do it, do it, does it work? yay!" In terms of adding a 9v battery clip and making this battery powered, would that burn out the LEDs since it's more voltage than with the power source (which you had at 6v if I remember correctly?) I'm making a robot costume and I don't want to be connected to a wall power source.


    Reply 10 years ago on Step 6

    its just a power supply and a load. If you need a schematic for that, perhaps you shouldn't be using power tools called for in step 2. Srsly, did you even read this instructable?


    Reply 10 years ago on Step 6

    lol yeah sorry. its just that i dont want to burn my poor leds from wiring em wrongly im new in electronics u know. but i found another instructable better explained. sorry for the stupid question


    10 years ago on Introduction

    i'm sorry if you already said this but does this blink with the music? also is the pattern random? thanks

    1 reply

    11 years ago on Step 5

    does the circuitry in the leds break the connection between the positive and negative terminals of the leds, or do they actually isolate the emitter from the electricity and draw power all the time? if it is the latter, then you can just wire them in series but you need enough voltage for each of them if it is the former , however, there is a possibility that the leds will shut off one after the other if wired in series, kind of like a chase light sequence, maybe because it uses a capacitor combined with the flow of current to time the blinks, but it really depends on the design of the circuitry inside them

    1 reply

    Reply 10 years ago on Introduction

    If you put them in series, the whole string blinks at once. And they draw way more current then a standard LED by itself. LED throwie tests show only 25% the life of throwies made with "super bright 10mm" LEDs. What does that mean? I dont know.


    10 years ago on Introduction

    What neat project and a great video (props for the cover song). It almost appears that the lights are coordinated to the song

    1 reply

    Reply 10 years ago on Introduction

    Thanks, yeah funny thing is they aren't. and they cant. But it sure does look at way. My theory is with that many lights in a grid, the viewer starts seeing patterns that are totally random. And the guy playing the song, that was totally random to.


    11 years ago on Introduction

    The flashing looks nice. But where's the fuzzy logic? I cant find any logic, fuzzy on non-fuzzy. I don't even see any fuzzies on the enclosure/box. Unless.... you count the very imprecise and fuzzy measurements made for the drilling holes as fuzzy ;-) I know how hard it is to drill in neat and even rows using a hand tool. I drilled eighty holes in a board for my upcoming instructable "The Tangible Drummachine" and that was not fun to do....

    4 replies

    Reply 11 years ago on Introduction

    Hey - so after thinking about this for a bit, I think Zachninme and I came up with a way to make this work on pseudo-fuzzy logic. I'd call it more of random chance, but at least it uses standard LEDs. Basically - hook up all of the LEDs in series with self-resettable fuses low-current(20mA), and then in parallel. In (my) theory (and I don't know much....) Current should flow in different magnitudes through each fuse/LED pair due to imperfections in manufacturing. This should sink current through some pairs and not others, but once too much current is flowing through the pairs, the fuse kicks out and a new pair lights with the extra current available. Each pair should repeatedly flicker at some (most likely super-high) frequency. I think we should be able to control that frequency, though, with a capacitor somewhere. What do you think?


    Im going to say thats out of my league to comment on. I might, however, be interested in breadboarding it. If i understood the self-resettable fuse part.


    Reply 11 years ago on Introduction

    I guess it could kind of mean pseudo-PWM to reduce the light output to an average of 12.5 LEDs by having them blinking randomly... I don't know. But I do know that I want one. And maybe some other colours of LED for a more Mathmos-y feel...