Burning Man project...

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cmndr
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Joined: Tue Jun 22, 2010 10:35 am

Burning Man project...

Post by cmndr » Tue Jun 22, 2010 12:02 pm

I have a bike that I have mounted two 5' diameter hoops onto (hoops made from tent poles), as the framework of a shadecloth awning. These hoops are attached vertically to the bike frame, parallel to each other, and the awning spans the top circumference, about 4 feet long and 2 1/2 feet wide. I would like to attach lighting to the hoops with sequencers that can be timed and coordinated with each other, and can be reversed in sequencing. My idea is to have multi-colored clustered LED's that give the appearance of slowly moving circles or fast patterns. I also hope to make the lights responsive to audio input. I can mount whatever power supply is needed, but hope to keep the thing as light and simple as possible.
Can you recommend to me suitable equipment to accomplish this? I am woefully illiterate about electronics, but can follow directions and assemble things like crazy.
Any help and suggestions will be much appreciated.

cmndr

macegr
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Joined: Wed Feb 27, 2008 4:44 pm

Re: Burning Man project...

Post by macegr » Tue Jun 22, 2010 2:45 pm

How many LEDs, what spacing and arrangement, what brightness, how long you plan to run this, etc? Do you have your heart set on RGB or are single colors good enough? How much soldering do you want to do? What's your budget?

You can go on eBay and buy standalone LEDs that just cycle through colors on their own. Cheap...but you can't control patterns etc.

You can get a bunch of shift registers and make boards that can control a lot of single color LEDs, or groups of different color LEDs. It's not easy to get smooth fading and mixing, but it's definitely simple.

I make RGB modules that have independent PWM, I also have connecting cables and even an Arduino shield that can make the LED modules respond to sound. It will cost more than the other possible solutions, but will be fast to assemble. The same modules are used on the new Fishbug light-up spine if you see that out on the playa. There were a few art cars using our stuff last year too, the biggest one was a giant light-up fuzzy heart you could climb inside and also a spinning star DJ booth.

cmndr
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Joined: Tue Jun 22, 2010 10:35 am

Re: Burning Man project...

Post by cmndr » Tue Jun 22, 2010 6:32 pm

each hoop is 16' circumference, and I'm thinking that a RGB cluster each foot would be nice. Brightness isn't as important, so lower powered LED's would be ok, and less amp draw would make it easier to run from a small 12 v. battery. Duration would ideally be maybe 10 hrs. I saw a website that sold strings called "triklets", no longer sold, that clustered RGB's in what looked like ping-pong balls. This is what it looks like they originally used for the first Cubatron, if you are familiar.
I'm willing to bite the bullet for a good system that'll make a nice effect, but it needs to be pretty compact and robust. I can't see hauling a laptop around to operate it.
Thanks for your input and help with this
David

60amp_relay
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Joined: Fri Feb 26, 2010 12:12 pm

Re: Burning Man project...

Post by 60amp_relay » Tue Jun 22, 2010 6:52 pm

If you are ok with simply alternating between two colors, or alternating between adjacent groups of LEDs, it's pretty straightforward. A simple astable multivibrator circuit and a few power transistors would do it.

The next big jump in complexity would be to use some kind of programmable microcontroller, like a PIC or an Arduino. That would give you all kinds of freedom to design patterns.

Just to give you a ballpark estimate for current draw, most LEDs work somewhere in the range of 10mA - 25mA. If you have an RGB cluster at each foot in a 16' circle, that's 16x3 = 48 LEDs, for a max draw of 1.2 amps. A battery that's rated for 12 amp-hours will give you a 10-hour run time.

Good luck!

macegr
Posts: 380
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Re: Burning Man project...

Post by macegr » Tue Jun 22, 2010 8:14 pm

Ok, I'll go ahead and post my link: http://macetech.com/store/index.php?mai ... ducts_id=1

That's the LED module, further down on the page you can see some examples of things people have done with these. We have cables from a couple inches up to 19", you just daisy chain the modules together with the cables. The only problem I can imagine would be the distance between the two circles. If you need to position any two LED modules more than a couple feet apart, I can't guarantee reliable operation. However we have had customers report 5 foot spacing with no problem in their application. If you did have problems running everything as one chain, the solution would be a second controller.

And this is the adapter shield that can respond to audio input: http://macetech.com/store/index.php?mai ... ucts_id=11

Since I've linked products outside of Sparkfun's store, I'll atone for my sins by suggesting a few Sparkfun components that would help a lot.

Just to let you know what else is out there, Sparkfun sells an RGB module that you could use to do pretty much the same thing (it uses the same LED as the ShiftBrite): http://www.sparkfun.com/commerce/produc ... ts_id=8579

With either solution you will need an Arduino, it's what the ShiftBrite Shield or Shifty VU Shield plug into, and contains the code that controls the ShiftBrites. Sparkfun has a few good options, this is most likely the easiest to use: http://www.sparkfun.com/commerce/produc ... cts_id=666

ShiftBrites don't want to run on 12 volts. They might survive, but overheating will be a possible problem (especially on the playa!), and you'll be wasting about 75% of your battery power as heat. However, a 12 volt battery is the easiest to find and charge, right? What we need is an efficient way to step down the 12V battery voltage to something the ShiftBrites can handle. Luckily, Sparkfun has just the thing: http://www.sparkfun.com/commerce/produc ... ts_id=9370

Connect the Sparkfun DC-DC converter to your battery, and set the output voltage to the maximum 5.5V. ShiftBrites will be happy, and you'll probably get days of operation from a single charge.

So now I've thrown like six different components out there to build this LED system. If you're not an old hand at this, you might be confused about the next step and whether you have all the components for the complete system. Don't worry, I've helped lots of people past this stage. If you can provide a sketch of your desired setup, with information like distance between LED modules and desired location of things like batteries, control boxes, and buttons and knobs to change patterns, I can draw up a wiring diagram and parts list for you. I can also help with the Arduino code to get the visual effects you want. Mechanical problems like mounting the modules and protecting cables will have to be done by you onsite, but that's probably enough to worry about in addition to the electronics.

esklar81
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Re: Burning Man project...

Post by esklar81 » Wed Jun 23, 2010 8:21 am

macegr wrote:If you did have problems running everything as one chain, the solution would be a second controller.
I agree that that's "a" solution, but not that that's "the" solution. One could also build such a system with a single microcontroller (uCTLR) and multiple drivers. Having a single uCTLR should make it much easier to coordinate/synchronize the two loops. Using a 64-LED driver chip for each loop would allow control of slightly more than an RGB cluster/foot of circumference. It would also make it easier to split the load to a pair of batteries.
macegr wrote:ShiftBrites don't want to run on 12 volts. They might survive, but overheating will be a possible problem (especially on the playa!), and you'll be wasting about 75% of your battery power as heat.
I agree that most of the energy would be wasted as heat, but it seems unlikely that this will be visible during the day and it's not that hot at night, is it?
macegr wrote:However, a 12 volt battery is the easiest to find and charge, right?
It's not hard to find 6 V lead-acid batteries. Personally, I'm rather fond of the sealed lead acid (SLA) batteries used for such things as alarm systems. They have the advantages of being cheap and easy to charge. If you had one for each loop, you could remove them from the system, wire them in series, and charge them as a single 12 V battery. (Just be careful about charging rate; a charger for an automobile battery is capable of much more charging current than small SLA cells can handle, but a trickle charge setting might fall in the SLA's range. There are also small chargers sold for such things.)

Alternatively, you could get a generator that takes power from the bicycle. Putting together a small charging circuit shouldn't be difficult. That way, you'd be able to charge the system without an external electrical source when you're not running the LEDs and supplement (and, thereby, extend the run time of) the batteries when you are running the LEDs.
macegr wrote:What we need is an efficient way to step down the 12V battery voltage to something the ShiftBrites can handle. Luckily, Sparkfun has just the thing: http://www.sparkfun.com/commerce/produc ... ts_id=9370Connect the Sparkfun DC-DC converter to your battery, and set the output voltage to the maximum 5.5V. ShiftBrites will be happy, and you'll probably get days of operation from a single charge.
Although the "12 V" and "6 V" are nominal voltages, a "6 V" SLA battery appears to fall comfortably in the stated range (5.5 to 9 V) of the ShiftBrite modules. That would save the trouble, expense and energy loss of the DC-DC converter. If you go with "bare" LEDs, you'll need to regulate the voltage from whatever power source you're using.

Have Fun,
Eric

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