# LED candles from scratch



## havok1919 (Oct 23, 2009)

After an overnight cure, the silicone can be removed from the 'masters'. Start by removing the candles from the base-- the candle wax should be visible from the bottom and you'll have a nice silicone rim around it.










I sprayed a little mold release on the *outside* of the silicone mold because I want to be able to turn it inside out while removing the candles. Then, while holding the rim of the mold with two hands I simply pressed the top of the candle against my knee-- that turns the mold inside out and forces the candle out of the silicone. The wax will break up, but that's fine. We're just interested in the mold.










With the mold completely inside out you can pick out any remaining bits of wax. I also looked for any 'hoops' (or loops) in the silicone and cut them (or pulled them out). You don't want anything that would form something like the handle of a coffee mug-- you need to be able to pull the mold off the plastic in one piece. Here's a mold inside-out:










Casting is just a matter of pouring in some liquid plastic and massaging the mold and slushing the liquid around so that it forms a hollow coating on the mold. As the plastic starts to set (it'll turn from the consistency of motor oil to more like syrup, then molasses, then finally fully gel) I keep turning the mold making sure it's evenly coated. 

For these candles (4-8" tall and about 1.5" in diameter), I ended up using about ~40-60ml of the Tap Quik Cast urethane plastic. I added some black tint since I'm planning on painting the candles to give them a little more depth and the black is more forgiving than the natural ivory color of the plastic. After about ten minutes the Quick Cast can be removed from the molds the same way as the original candles. You wind up with perfect little candle-copies.










Here's one shown on top of the skull for reference:










In the top of each hollow shell I drilled a hole that's the same diameter as the light emitting lens part of each diode. (The little square with wires is the particular surface-mount white LEDs I'm using. They're a "warm white" color which makes a really nice/natural yellow from the amber colored plastic.)










A dab of hot glue holds the LED in place inside the hollow candle. The wires exit the bottom to be wired up to something else later. (This is just a "test" candle-- the real ones will use longer color coded wires!)










With the LED in place another dab of hot glue and you can stick one of the flames to the top. (I like it that all the flames are unique-- looks a bit more natural than the identical ones from stores.) Although I guess it shouldn't surprise me, it looks remarkably like a candle. 










Finally-- power applied. It's hard to photograph, but even with just constant power (no flicker or anything yet) it actually puts out a very realistic 'candle amount' of light!










(and a little but more to continue...)


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## SavageEye (Aug 30, 2010)

I like it!!!


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## havok1919 (Oct 23, 2009)

With the lights off-- you'll see that both the amount of light and the color of the light is really like a candle.










However you color the plastic or light it will set the color/mood of the candle. Being an electronics-type guy I designed a little controller that will light and flicker the candles in various ways. Once the circuit boards show up and I get the code written I'll post a video or two. 

If you used a translucent plastic that would also improve the "lit" candle look as well, but I'm happy with what I've got for now.

I hope that this gives you some ideas or inspiration. It's more involved and time consuming than some other ways to do it, but it does provide a solution to a particular problem. Happy haunting!

-Clay


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## Wolfbeard (Sep 22, 2008)

That is a great tutorial! Thank you!

Eric


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## havok1919 (Oct 23, 2009)

I decided to try using some of the same casting resin that the flames are made of to cast an entire candle. I added three drops of Smooth-On "So Strong" red tint to 60ml of SmoothCast Color Match 325 resin and ran it in my largest candle mold.

From there I repeated the LED installation and flame attachment. The transparent resin lights up in a suitably candle-like fashion:



















Then for comparison, I painted one of the opaque grey candles I showed earlier:










I kinda like 'em both. Not sure which I'll use.

Here's a quick pick with one of the skulls painted up:










(the candle is just sitting on top-- it needs to be mounted and have some more "run-off" added to look better)

-Clay


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## Crunch (Oct 23, 2008)

Right on!!!


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## havok1919 (Oct 23, 2009)

Finally took some video with a few different lighting selections (kinda hard to tell the differences in the video-- the camera tends to brighten things up a bit).


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## dionicia (Nov 5, 2006)

That looks really good. 

I like the second one that you painted. It looks more creepy.


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## archos_user (Oct 20, 2009)

What did you use to 'flicker' your LED's?


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## havok1919 (Oct 23, 2009)

archos_user said:


> What did you use to 'flicker' your LED's?


I actually ended up just rolling my own. Basically it's a little microcontroller that runs the lighting program and then I used regular ethernet cable to wire up the LEDs. (It's cheap and easily available in long lengths.) Originally the controller was setup for 12 LEDs, but I decided wiring was easier if I just did eight. (Ethernet cable is four pairs of wire, so by just having each port run four LEDs that makes for one pair of wires per light.)

The board design supports 12 LEDs for 'flicker' (you could use multiple LEDs per candle too) and then one high current RGB (red/green/blue) lamp. There's also room for switches and two knobs to control parameters. (I didn't hook any of that stuff up though-- was low on time and the fixed lighting parameters worked fine for what I needed.)

It runs off a 5V DC wall-wart type power supply.










-Clay


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## havok1919 (Oct 23, 2009)

Before I forget... Here's the candles in action on Halloween 2010:


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## RacerX45 (Apr 30, 2008)

*Awesome job!*

Great job on the candles and the tutorial. I am looking to switch my candles over to leds (versus 110v volt flicker bulbs). Any chance of getting a tutorial on how you made the flicker component? Again, great job, the whole set up looks great. I love the flaming pumpkin head.

Randy


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## Rev. Noch (Sep 2, 2008)

RacerX45 said:


> Great job on the candles and the tutorial. I am looking to switch my candles over to leds (versus 110v volt flicker bulbs). Any chance of getting a tutorial on how you made the flicker component? Again, great job, the whole set up looks great. I love the flaming pumpkin head.
> 
> Randy


Agreed, I would like to be able to come up with some of those flicker controller boards. They would be useful in candles as well as even pumpkins.


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## Misdomt (Oct 26, 2010)

Ya, great question "archos" , I'm also dying to know if its some resistors or what. I took apart one of those LED tea lights and there isn't a whole lot to them.


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## DMRaver (Nov 2, 2010)

Clay,

Okay. So first of all, your candles and skulls look really really cool! Very inspiring. Like some of the other haunters I'm also wondering where/ how you got/ made your microcontrollers and used them with your LEDs? 

I'm not sure why nobody else seems to be wondering about this too... did I miss the tutorial? But how did you construct the propane burner for the Jack? I'd love to know more about that setup.

-Dave-


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## AuraofForeboding (Oct 4, 2009)

Wow, looks great! Like everyone else though, I'm very interested in where you got the microcontroller!


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## havok1919 (Oct 23, 2009)

Hey everybody--

Thanks for the compliments. Everything made it through Halloween without any failures and the only damage was a flame getting broken off one of the candles (they're only hot-glued on, so I just melted the glue and stuck it back in place during a lull from the TOT crowd ;-). The candles in the fog were really effective-- quite a few kids spent time trying to figure out if they were real or not. 

I'm an engineering consultant by trade so I do a lot of microcontroller and LED lighting stuff for clients. Since I was totally out of time, I just slapped together the controller design and had some 'quick turn' prototype pcb's made and wrote the program that runs the LEDs a few days before Halloween.

[Here's the technical version for those of you that are so inclined/curious: I implemented eight current sinks using the microcontroller (done with N-channel MOSFETs). Software in the microcontroller generates a unique and programmable brightness for each LED using a software based pulse width modulation (PWM) technique. The microcontroller is an Atmel ATMega48 running from the internal 8MHz oscillator. That's enough speed to run about 12 software PWM's at ~70Hz (fast enough that the light won't "flicker" unless you want it to). A lookup table is used to define different brightness levels from 'dim' to 'maximum'. For each LED a random number is generated that maps to a brightness level. Then, for each LED another random number is generated which is used to set the time until a new brightness is selected. When the (random) time until the next brightness elapses, another new random brightness is generated-- but instead of immediately going to that setting the program smoothly ramps the light between the 'new' and the 'old' brightness. That eliminates the "digital" flickering that you see in a lot of the little LED tea-lights. By varying the maximum time between new values and by varying the maximum 'depth' of flicker (how fast it can change) you get different effects.]

The non-technical version: The little microcontroller board can control up to twelve individual LEDs (I only used eight) with varying levels of "flickering" or other lighting effects. For each effect, two knobs can tweak the look of the effect. All the LEDs are unique, so you don't run into any "every Nth light looks the same" problems like on some light strings. 

For wiring I just used Ethernet cables. They're cheap ($2 for a 10' cable which is enough for four LEDs), and if you cut the end off one inside you'll find four pairs of wire. Each pair of wire connects to an LED in whatever you want to light up.

There's also an RGB LED controller on there that's designed for one high power RGB LED. Basically something that you'd want for a single bright colored spotlight or color wash, etc. I didn't use that this year. ...but good to have the option. 

Soooo... It's not really an easy DIY project for most people (since there's making circuit boards, programming chips, surface mount soldering, etc.), but if a few people were interested I'd polish it up and turn it into something you can buy-- I'd guess I could produce and sell the controller boards for maybe ~$25-35? (maybe a little more with a plastic case) Cables and whatever LEDs you want to use would be up to you.

I have a few 'programs' that can be selected with some little switches on the circuit board. There's the flickering LEDs, 'fireflies' (little random bright flashes that fade), 'blinking eyes' (pairs of LEDs that turn on and dim/turn off in unison), and 'heartbeat' (that throbbing/beating light effect in the chest of my scarecrow in the video). 

Let me know if you'd be interested in an LED controller like I described and/or if you think the price is reasonable. If a few people are interested I'd go ahead and 'productize' it and offer it in the marketplace. (I want some more for my own use next year, so I'll probably end up doing the work *anyway*...) 

-Clay


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## havok1919 (Oct 23, 2009)

DMRaver said:


> But how did you construct the propane burner for the Jack? I'd love to know more about that setup.


I might have written a post about that last year, but I can document it and put it in a new thread in the Tutorials section so it's findable.  I'll have to take some pictures over the weekend. It's simple enough, but fairly impressive looking.

-Clay


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## dionicia (Nov 5, 2006)

I'd be interest. I have a buttload of old school plug in light candles I bought that I wanted to modify to LED. This would be cool for those.


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## RacerX45 (Apr 30, 2008)

I would be interested in a few as well. Thanks!

Randy


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## Rev. Noch (Sep 2, 2008)

I would for sure be interested in the little light controllers.

I have been struggling with those blasted flicker bulbs in the last couple of years. Not only are they really expensive, but they don't seem to last very well. Flickering LED's should be way cheaper, more durable and best of all look even more realistic.


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## havok1919 (Oct 23, 2009)

Looks like a few of you would be interested in the light controllers, so I'll go ahead and turn those into something suitable for someone other than me to use.  Probably be a couple months before I have time to finish up the project, but I'll post back here with progress on occasion...

-Clay


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## RacerX45 (Apr 30, 2008)

Sounds great! Thanks for doing this!

Randy


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## Xane (Oct 13, 2010)

I'd be interested in a controller as well. I'd love to be able to create some LED candles that are actually bright enough to be candles. Those little tea lights are worthless to light up a pumpkin (the tap-light style ones are bright enough but look lousy if you have big gaps in your pumpkin pattern) and even the bigger LED candles are simply not bright enough to be more than an atmosphere effect. It'd be interesting to find some way to create a more realistic flame as well.


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## Misdomt (Oct 26, 2010)

I too would be interested in a controler. Let me know the details, cost etc... thanks.


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## AuraofForeboding (Oct 4, 2009)

I would definately be interested. What you've done is really awesome! Can you tell us any more specifics about the LEDS you use? Are they ribbon LEDS, and you just cut them off individually? What is the brightness level? Or mcd I guess...


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## havok1919 (Oct 23, 2009)

AuraofForeboding said:


> Can you tell us any more specifics about the LEDS you use? Are they ribbon LEDS, and you just cut them off individually? What is the brightness level? Or mcd I guess...


They're 9000mcd warm white LEDs. The ones I had were from eBay and were originally on flex strips, but I desoldered them and just wired them up directly to save a little space.

If you search for "5050 warm white LED" you should find them either on flex or unmounted. They're only about $0.40-0.50 each (shipped) in smallish quantities (say, ~30).

They're low current LEDs-- only 20mA and there's three of them in each little surface mount device. The package is about 5mm square.

One handy thing about the surface mount LEDs is that they're flat on the top, so for my flames I just sanded the base flat and hot glued them directly to the LED. 

The LEDs are also pretty 'wide' angle. (ie, the light comes out in ~120 degrees or so-- like a flood light and not a spot light.) That's actually kinda nice for our application too because the illumination is very even-- there's no 'lens' effect like on round top LEDs that make the center of the light very bright relative to the surrounding area.

-Clay


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## havok1919 (Oct 23, 2009)

Xane said:


> I'd be interested in a controller as well. I'd love to be able to create some LED candles that are actually bright enough to be candles. Those little tea lights are worthless to light up a pumpkin (the tap-light style ones are bright enough but look lousy if you have big gaps in your pumpkin pattern) and even the bigger LED candles are simply not bright enough to be more than an atmosphere effect. It'd be interesting to find some way to create a more realistic flame as well.


Since the LED outputs are all unique (there's no pattern or repeats on any of the outputs) I suspect that you could gang several together in a cluster and make much larger flames and/or use brighter LEDs. 

Another option I could do would be to use some slightly different parts that would support *much* brighter LEDs. (Right now each output can go to about 50mA which is more than enough for small LEDs which are typically more like ~20-30mA.) It's a simple change (basically just using a higher current part) and it would support very high current LEDs-- over an amp or more, so you could drive high current LEDs up to closer to an amp or more. That would raise the price a bit (more current = more expensive parts). 

Maybe what I'll do is just have a "standard" version for everyone that just wants to use small LEDs in candles or props and then have a "high power" variation for anyone that wants to use them for scene lighting or JOL's or whatever.

(I actually already have three 'high current' LED outputs on there to support the RGB floodlight, so it's just a matter of using those same parts on all the channels.)

-Clay


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## imindless (Sep 16, 2010)

I would be interested in learning the exact microcontroller (which you have already told) and every other component you need to create one of these and maybe a step by step guide to setting one up. I am more of a hands on learner than a buy-it-now type of guy if I can be, for the most part. So if you would be willing to do a tut on it that would be awesome


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## havok1919 (Oct 23, 2009)

imindless said:


> I would be interested in learning the exact microcontroller (which you have already told) and every other component you need to create one of these and maybe a step by step guide to setting one up. I am more of a hands on learner than a buy-it-now type of guy if I can be, for the most part. So if you would be willing to do a tut on it that would be awesome


Oi... That might be a bit more than I can take on!  

There's an awful lot of disciplines and software behind that relatively simple item. On the one hand there's electrical engineering to design the circuitry, printed circuit board design and layout (and software to do that) and then real time embedded systems programming (using the 'C' programming language). That's just the implementation side of things and doesn't really cover design and just the background in the art to know *how* to do it. (Pulse width modulation, realtime systems, state machines, etc.)

I'm not trying to make it all sound like impossible-to-learn arcane black magic; I'm just not really sure where to even start and I think it'd take weeks of time and dozens of lessons to get to the point where you'd be 'dangerous'!

That having been said, I found this link online (it's even sorta Halloween themed!) and it looks like a pretty good introduction to microcontrollers and programming concepts in general:

http://todbot.com/blog/spookyarduino/

The 'arduino' platform is a pretty common hobbiest controller system that has LOTS of online information. Another good starting point would be:

http://www.ladyada.net/learn/arduino/

You just have to be prepared that you'd basically stepping in to electronics and programming at a minimum just to get to the "blink a light" stage. It's very doable for anyone with an interest and a few dollars to invest in some basic stuff, but it will require many hours to get to the point where you can do seemingly very basic things. (that turns off/burns out a lot of early engineering students)

If you have an interest in learning the basics and working through everything I'd suggest the tutorials above to get your feet wet. If you're more into the destination than the journey, buying pre-built modules may be more fun in the long run. Everyone's different in that regard...

-Clay


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## imindless (Sep 16, 2010)

Well if you wanted to or thought about it, this might be just the group project that a lot of us would love to try. The group tut is spread out depending on how intricate the work is and we get together at a designated day/time and all work on it together and the teacher walks everyone through it and that way if they have any questions everyone can pitch in and help. 

I will check out the links and see if anything would be helpful though.


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## AuraofForeboding (Oct 4, 2009)

Thanks again for all the info! I imagine, getting the surface mount LEDS on a ribbon would be easier to wire, cause those little buggers are SMALL and don't have the normal long wire leads like regular LEDS. I'm curious to try this! With the leds being such a broad angle, are your "flames" just as bright at the tip?


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## havok1919 (Oct 23, 2009)

AuraofForeboding said:


> I'm curious to try this! With the leds being such a broad angle, are your "flames" just as bright at the tip?


They're really consistent brightness in the plastic. Even though the LED pattern is wide angle because the 'flame' sits right on top of the LED all the light is captured in the plastic and illuminates it really evenly.

-Clay


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## Terra (Sep 23, 2007)

Thank you for such an in-depth and helpful tutorial. The flickering is so realistic!


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## havok1919 (Oct 23, 2009)

Just a random update-- I've purchased most of the parts for a batch of the controllers, so I'll definitely have these available before the season this year. Hopefully early spring. 

We're remodeling our business at the moment, so it'll busy with that and it'll probably be February until I'm really able to finish things up, but I'll get to it ASAP thereafter.

I'm changing how things work a little for the 'sellable' version. It has two knobs on it which are used for selecting the particular effect desired (candle light, fireflies, blinking eyes, etc.) and then once the effect is selected the knobs control the intensity/timing of the effect. (That way you can just dial in what you're looking for without needing any programming expertise or equipment to go with it.)

-Clay


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## Morbiddious (Apr 8, 2010)

Love the skull candles, but I'm really diggin' the flaming pumpkin ! Awesome !!!!!


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## stygma (Mar 13, 2009)

Awesome effect! When you get the boards built I'll take 4.

-Mark


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## Terra (Sep 23, 2007)

Thinking about it, I'd love several circuit boards too! These are really awesome controllers


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## RacerX45 (Apr 30, 2008)

Terra said:


> Thinking about it, I'd love several circuit boards too! These are really awesome controllers


I totally agree. Looking forward to switching my candles over to LED's. I'm in for at least 3, maybe 4.

Randy


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