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Wearable Arc Reactor

by MishaT, published

Wearable Arc Reactor by MishaT Oct 21, 2012

Description

Just in time for Halloween! A printable, wearable arc reactor based on the Mark I movie version.

There are already some great arc reactors on here, but I wanted to take my own crack at it.

Recent Comments

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Thanks! You are right, and some day I'll get around to revisiting this design, but I have a lot on my plate at the moment.
First off, awesome design!! Looks great and very creative.

As a little bit of constructive criticism, the top and the crystal do not fit together without massive amounts of sanding and filing. It would greatly help if you could design a little bit of play in-between all of the press fit parts. Maybe an extra +/-1mm of space on the radii of the concentric circles that fit over the crystal, and an extra 0.5mm of width on each the slots on the outer and inner rims of the crystal.
I think I did .1 or .15. The lowest you can get away with while still having a nice top finish.

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License

Wearable Arc Reactor by MishaT is licensed under the Creative Commons - Attribution license.

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Instructions

BOM:

5 M3x10 screws and nuts
14 White 5mm LEDs
10 Blue 5mm LEDs (optional)
Resistors (Depends on your configuration)

Print the crystal in clear PLA and the other parts in a dark color, metal or black are best. For best result print the crystal with a low rectilinear infill and no more than two shells.

Assemble everything except the base. I put some aluminum tape on the underside of everything that I did not want to be translucent, but this is optional.

Put white LEDs in holes that are not covered from above by the top piece (10 around the outside and four in the middle), optionally put blue LEDs in the other holes to give a nice bluish glow to the outer ring. I sanded the LEDs before wiring them in to give them a more diffused glow.

Wiring of the LEDs will depend on your particular LEDs and the power source you use. I am running off a 9v battery and have eight parallel rungs of 3 LEDs in series with a 68 Ohm resistor. My LEDs are a little under-powered and could be brighter with smaller resistors or if they were wired two in series instead of three, but they are bright enough. You can use this calculator to design your own circuit: led.linear1.org/led.wiz

Cut a hole in a t-shirt just big enough to fit the crystal, pin the edge of the cloth in the groove between the top and base pieces and secure with screws. Attach some sort of belt using the slots in the base to go around your chest so the arc reactor does not move around.

You will need to run a wire under your clothes down to your pocket to your power supply as there is no room to build a battery into the reactor itself.

Enjoy!

P.S. I strongly recommend not trying to get on a plane with this on.
First off, awesome design!! Looks great and very creative.

As a little bit of constructive criticism, the top and the crystal do not fit together without massive amounts of sanding and filing. It would greatly help if you could design a little bit of play in-between all of the press fit parts. Maybe an extra +/-1mm of space on the radii of the concentric circles that fit over the crystal, and an extra 0.5mm of width on each the slots on the outer and inner rims of the crystal.
Thanks! You are right, and some day I'll get around to revisiting this design, but I have a lot on my plate at the moment.
When you calculate the resistor values, do you use the maximum voltage of the battery or the nominal? For example a typical 9V battery has about 9.6V when fully-charged. Do you use the 9V figure or the 9.6V in your calculations?
I think I just used 9V, it won't make much of a difference.
Okay, thanks for the tip. BTW, what do you recommend as the infill for the crystal? Your instructions said "low". Are you thinking something like 0.1 or more like 0.3? Thanks.
I think I did .1 or .15. The lowest you can get away with while still having a nice top finish.
what did you use to enclose the battery and switch?
I just threw something together quickly, it wasn't very good. I'm sure if you search Thingiverse you will find lots of 9v battery holders.
I actually tried looking, but I didn't see anything I liked. Would you mind sharing it? I would like to print it out along with the arc reactor you designed.
PM me your email, but I doubt you'll find it useful. It is sized for whatever junk switch I had laying around.
Has anyone got a bit better picture of how they've wired
You can use this easy calculator to design the circuit for you based on your battery, and the LEDs that you have: led.linear1.org/led.wiz
Thanks very much for the info. Ill let you know how I get on
Would I be able to get a copy of the crystal with slots? They would be handy!
Sorry, I've erased them from the original model long ago.
I have all the pieces perfect except the crystal (which seems to be 100%) is missing the slots for the resistors? Everything else is perfect any ideas?
I removed the resistor slots so people can wire it up as they want
Hi there, just wondering what printer you have? I'm using a replicator 2 and am wondering what settings and layouts i need to make this successful. will the top layer print face up with the slotted tops? Thanks!
I have a RepRap and have not had the opportunity to use a Replicator 2. Perhaps someone else on here can share their settings.
Hi MishaT,
Are you willing to sell me one? I don't have a 3d printer and I can't solder for the life of me. I would like to buy one so I can wear it on my sons birthday. He is having an Iron Man themed birthday party. Thanks, and let me know.
Hi! Unfortunately I'm in the middle of moving and my printer is not up and running. I'm sure if you find a hackerspace in your city someone would be happy to print one for you.
Just finished building mine, and it came out great. Thanks for adding it here.

A few suggestions, based on the issues I ran into. The crystal did not want to fit into the top. I'm assuming I was just outputting a little more plastic than you were when you designed it, but I had to spend a couple hours grinding away material with a dremel and files before the top could be squeezed on. It might be a good idea to update the model with a little more tolerance for printing inconsistencies, since a super-snug fit isn't really required anyway.

If I make another one, I might try increasing the space for the circuitry slightly by hollowing out the base a little bit more, or maybe also putting strategic holes for screws between the LEDs to act as terminals for electrical connections to reduce the amount of soldering required. And perhaps a second shelf that sits between the crystal and the base, which can isolate the negative (or positive) side of the circuit to reduce the necessity for insulated wires. After connecting all the positive sides of the LEDs to the main battery pack wire, you could stick a plastic plate on top, which would have holes for all the negative LED leads, and connect them all to each other without having to worry about shorting.

Certainly not necessary for an electrical pro with a decent soldering iron, but for someone (like me) doing this sort of project for the first time, changes like that would save a lot of time and frustration.

Anyway, thanks for saving me a lot of modeling time by uploading this. I'm very happy with the end result.
Thanks! Your copy looks really cool! Originally I had the whole circuit layed out in the plastic with connection channels and everything, but then decided to take it out so not to dictate how people should wire up their LEDs. This way people can set up their LEDs any way they want and account for variations in LEDs and power sources.
That makes sense. Case in point, I actually didn't use any resistors, since 8 rechargeable AA batteries provided the exact 9.6V I needed for 3 LEDs.
You still need a resistor unless you buy LEDs with a built in one. It is there for current limitation as an LED doesn't really have any internal resistance of its own.
Oh, I thought they were only needed if the voltage was too high for the LEDs. What happens if you don't use any? I ran mine pretty much constantly at a convention this past weekend and didn't have anything burn out.
An LED is just a diode, if you don't have any resistance in a circuit you essentially create a short. Some LEDs come with built in resistors, it is possible you have some of those.
So the only viable option for LEDs is to provide more voltage than is needed, and then use resistors to burn off the excess as heat? That seems very inefficient. I clearly have a lot to learn, so I'm trying to find information elsewhere, but much of it is conflicting.
LEDs will have a given rating, for example 3.3 forward voltage and 20 mA limit. Depending on what your voltage source is you need to add a proper resistor to limit the current below your LED's threshold to keep it from burning out. Look of Kirchhoff's circuit laws for help calculating your circuit.
I did the math and used batteries/LEDs that equated to 0 ohms of resistance needed (even while staying well below the LED's maximum voltage range). I assumed this meant I needed no resistors, but now I see that there are, in fact, 0 ohm resistors, which I guess is what I should be using for my setup.

Thanks for bearing with me on this.
I'm confused on how you got that number, can you sketch out your circuit?
Apart from the different voltages and lack of resistors, I have it laid out pretty much the same as yours. 8 parallel sets of 3 LEDs each, connected to 8 rechargeable AA batteries. The LEDs (http://www.taydaelectronics.com/leds/round-leds/3mm-leds/blue/led-3mm-blue-water-clear-ultra-bright.html) have a forward voltage rating of 3.2-3.4V, and the batteries are 1.2V each, for a total of 9.6.

When I enter it into the calculator at exactly 3.2, it suggests to use 12 series of 2 each, with 180 ohm resistors, (presumably because it's programmed to always use resistors), but if you change the LED voltage to 3.19999999, it suggests 8 series of 3 with 1 ohm resisters (presumably because it only uses integers and always rounds up).

But mathematically, assuming it went below 1, it should suggest a resistor at some infinitesimal fraction of an ohm.
Got it, looks like you are lucky in that between the resistance in the wires and internal resistance of the battery you are close enough to the required resistance to not burn out your LEDs. This will not always be the case depending on your circuit layout.
My son and I built one of these for his Halloween costume dance.  Printed great on our R2 with only minor cleanup required to fit everything together.  The LEDs pressed into the recepticles nicely.  Be prepared for sticker shock on the blue LEDs.  Might be a good idea to just print the clear part as transparent blue and stay with white LEDs.
That's great to hear! Check eBay for really cheap LEDs.
Instead of wiring up LEDs, I managed to find a small set of indoor battery powered 'light strings' from Noma. They're essentially a string of  24 tiny surface mount LEDs already wired together. I set them in place and hot glued them. 

They work great for the $8 I paid for them as Canadian Tire!
Thank you! now i don't have to design my own :)
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