Tom Ramcigam (magicmarmot) wrote,
Tom Ramcigam

Secrets of the Guardian

This is for those of you who are interested in the dirty details of the Project from Hell, otherwise known as the Guardian of Forver facade for Convergence 2003. It is pretty long and gets a little ugly in places, so if you really don't care, it would be good to skip.

Also bear in mind that this was my interpretation of the experience, and I am biased. :)

Some months ago, [Bad username: cajones> came to Barb and I about creating a new facade for Convergence this year, after our rather successful effort last year with the Indiana Jones Temple facade. There were two basic ideas: one was to do a full-size Tardis, which would have ended up being too small for the doorway, and the Guardian of Forever from Star Trek TOS. We did think about some other ideas, such as the Time Machine from the H.G. Wells story and movie (way too complex) and the Time Tunnel (cool but obscure). We put some thought into it. After a lot of consideration, we determined that a Tardis would be tremendously cool, but difficult to pull off accurately (and accuracy would be paramount) and would have to be made quite sturdy in order to be used by con-goers for the various picture-taking opprtunities. Besides, the walk-through facade idea is just too much fun to walk away from. And really, it&apos;s just a big donut. How hard could it be? So we got a tape of ]look</i> like fiberglass. But it's difficult to tell, as we really couldn't agree on how the thing looked. And this became more of an issue as we progressed. You see, if you watch the episode, you will notice that it actually changes in different shots. We were unable to agree whether the surface was textured, or flat with a painted texture. We couldn't agree on the color. The lights are different in different shots. I have to think that many of the problems we ran into were the same ones that the designers did in the original series.

Also, the size. We have a limited space to install the thing in the Radisson. There are beams, a low ceiling, and other stuff to consider (like the fire alarm light and smoke detector) that make it difficult.

So we came up with several different versions and presented the ideas to the board. The most cost-effective idea looked to be building it out of foam, much like last year's facade. Big problem was the translucent front piece; original testing led me to believe that regular white beaded styrofoam treated with a heat gun would work.

They ranged anywhere from a 2-D version that was just there to a full 3-D version with lights and sound and fog and video.

Ah, fog.

If you've seen the episode, when the Guardian actually starts it's time-travel bit, it spews fog. It's pretty obviously dry-ice fog, which is just fine when you have very small limited pieces that you're doing (like filming a TV episode), but when you have an entire convention and the thing will basically be unmanned for many hours, dry ice is difficult, expensive, and generally a pain in the ass.

Luckily, I have a second option, which is to use a water/glycol fogger with a fog chiller. A fog chiller is easy, and it basically takes regular ice, which is cheap and plentiful. And the fog lasts a lot longer than dry ice fog.

There were problems.

First, when some people see fog, they complain. Primarily that it affects their breathing or that it might affect people with athsma, never mind that the fog chemicals are food-grade and are actually used to humidify rooms and ingestible materials.

Second, a technical problem. There is a big ol' smoke detector mounted 12 inches above the center of the mainstage door. And it's an optical detector, which means that fog will set it off. Although the chances of actually triggering it were fairly small, there was still a chance, and we needed to get an okay from the hotel.

So we decided to build the capability for fog into the guardian, and if it turned out we couldn't use it, we just wouldn't use it.

At the same time, Barb and I were having to finish up some mandated work on the house, and it was taking up all available time. We knew that we were not going to be able to finish this thing by ourselves, so Barb called up Roadkill who had offered his help previously.

We went over to the Roadkill house, where we were treated to an impromptu showing of some of the work he's done with plastics for costumes and props. It's really quite impressive. We also watched the episode and talked about possible ways of building the guardian shell, as well as locations.

Remember, this thing is big.

Something that came up in these discussions: the lights. We were pretty much all decided that it had to light up and talk. And with the size of the thing, that meant a lot of lights. I was originally looking at 150 watt halogens until Roadkill brought up the point that the shell would inevitably be made of plastic, and with the number of lights we were looking at, heat would be an issue.

At the end of the night, the divisions were becoming fairly clear, that Roadkill had a lot of mechanical prop-and-set building experience, and I was very comfortable with electronics and electrical systems. Given the time constraints and the project load I was already under with the house, I brought up the idea of my handing off the mechanical build and just doing the electronics.

At the time, we were looking at the guardian operating in several modes:

1.) A live microphone that someone could talk into , and the lights would respond.

2.) A CD with recorded tracks that would trigger lights and fog with a program tied to the sound.

3.) A motion sensor that would trigger the pre-programmed tracks, then hold off for several minutes before allowing re-triggering.

This is really a pretty complex system, so I decided that a small microprocessor would be able to handle it. I have a new development system that would be perfect for something like this.

I also had to look into cool and efficient lights. In a word, anything that is cool and efficient is expensive. After much searching, the only thing I found that was within budget was packs of fluorescent bulbs on sale at Menards. Thety featured the equivalent of 60-watt bulb light output, but only used a quarter of that. Packs of 4 for $9.00, which is an amazing price; I ended up getting five packs.

My initial happy thought was that these were pure electronic ballast lights, which would be essentially instant-on. It meant that the lighting controller couldn't be a simple color organ, but would have to be an all-on/all-off controller, like a light switch. It meant I'd have to build the power controller circuit, but that was something I wanted to do anyway for another project.
I was getting a little concerned though. We essentially had six weeks to get the thing done, and with all the work I had left to do on the house, that was pushing the development curve a bit too much.

Then came word: No fog. Too much risk with the smoke sensor.

Taking the fog out of the equation simplified the controller. Now it just had to synchronize lights and sound. Unfortunately, the cheap-ass fluorescent bulbs had a rather negative feature to them. They had a turn-on delay time. About three seconds cold, shorter if they had been on recently.

That meant that a circuit that responded to a microphone was out. The lights just wouldn't respond until several seconds after someone started talking.

So, I ended up deciding that it would be CD-only, with lights responding to the CD.

This was simple enough that I didn't even need the processor. I decided to use one track of audio for the sound, and put a control signal on the other track. If I had a CD player that would repeat, I could just set it and forget it. And if it had a random function, all the better.

And just on a whim, I sat down and listened to the episode. As it turns out, most of what the Guardian says I could extract into tracks.

So I had a plan. On relatively nice days, I would come home from work and work on the ladder to finish the house. On rainy or windy nights, I'd work on the Guardian.


The circuitry was relatively simple. The light control is a relatively simple triac with an optoisolator and some snubbing for RF control. The only problem I ran into was that all the information that I had was that the drive was high-side, and it turned out to be a low-side drive. That cost me a day to figure out. The rest of it is a fairly simple comparator with an adjustable 0-5V reference and a direct audio feed into the inverting input. When audio is present above the reference voltage, the compaator output goes low, and sinks the LED of the optoisolator, turning it on.

I did two separate channels and set the references differently so the two chains of lights would operate slightly differently. The output circuits were designed to handle 10 amp continuous loads, which is pretty heavy-duty.

Programming the sound took about three nights. I first had to set up the audio, then create a control track designed to match the syllables on the other channel. By hand. I heard the guardian talking a whole lot over those three days.

On the other hand, Roadkill and Barb were having fits. Roadkill decided to take the mechanical design and run with it, and Barb was freaking out over his design changes. Roadkill managed to get the discards from the Chanhassen Dinner Theater, which netted several pieces of what amounted to industrial-strength foamcore (5" of foam sandwiched between 1/2" of plywood), and located some clear PETG plastic sheets at a plastics company.

He also changed the shape.

There was much arguing between Barb and Roadkill over the shape. I avoided most of it, but Barb is not one to hold back when she's frustrated.

They finally compromised. If I were to say that Barb is not one to compromise either, you will understand just how difficult these times were.

I decided that the interior flats would be covered in aluminum foil to increase the reflectivity of the lights. I should have mentioned that the aluminum foil should have been fastened down with spray adhesive. I also should have mentioned that aluminum foil, being made of aluminum, is a metal, and therefore conducts electricity. There was an incident during the first night of the wiring phase which led to my being called in to finish the wiring.

We wired up 20 sockets. Two separate legs of ten sockets each. The two wiring circuits was an idea that I had, because when I looked at the guardian videotape, I noticed that there were two separate sensitivities of light, and I believed that I could reproduce that.

Barb, Roadkill, Peter and Emily had also formed the plastic shell out of the PETG sheets. When I finally saw them, Roadkill had already started painting them with small swirls of color.

Have I mentioned that this was not what Barb had envisioned?

By the time we were done with the lights, Roadkill had put the first main coat on the inside of the guardian.

It was pink.

Barb nearly had a fit.

Now consider that the paint was a mixture of acrylic caulk and acrylic paint, about the consistency of... well, caulk. It does dry darker than it goes on, and it was really opaque. But when she saw it, it was pink.

Remember the part about Barb sharing when she is frustrated? Have I mentioned that that sharing is usually not a nice, gentle thing?

So Barb apparently called Roadkill the next day, and had him put another coat on the inside that was a lighter color. Apparently there was some miscommunication; she had wanted him to strip the old coat and do a new coat that was less opaque, and he did a second coat of a ligher color.

Again with the frustration.

So we needed more light.

After several suggestions, I ended up going to Menards and got more lights. We finally ended up with 32 total. Barb also had me pick up a bunch more acrylic caulk in case we decided to strip and repaint the shell at the last minute.

By the time we finally got to the hotel, we still hadn't seen the whole thing together. We did a quick test with one of the plastic pieces over the frame, and it worked well enough that we decided that we didn't have to strip and repaint the shell.

Final assembly, and despite a small hitch with me blowing a fuse, it worked. And it worked all weekend. And as a little added bonus, the individual lights all each had their own individual response curves, so aside from my two channels of lighjting effects, there was a decided sparkly effect that happened that just added to the overall effect.

And when all was said and done, it turned out to be pretty damn cool.

There were definite lessons to be learned on this one.

  • Start early.

  • Have a project plan.

  • Have a clear deliniation of who is responsible for what.

And a good supply of valium can't hurt.

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