Make a shipping crate for some of the parts

The title says it all: I made a wood box to hold the 6 straight bars for the vehicle. It's reasonably compact and keeps the bars from knocking against one another.


Video!

I packed the vehicle parts into the car (using the freshly made packing crate for the straight parts) and headed to Lux Lounge (666 South Ave.) Around 9:30 or so I got some help getting all the parts into the back yard. In all, I think it took about 30 minutes to get the whole thing assembled in the dark. I think about 12-16 people got a chance to try it out … I took some video and posted it on my other website a few weeks ago … same as here.

John and I took it to a nearby parking lot to see if we could get it to go straight. The traction was so much better than in the dirt that we actually broke one of the spokes on the steering wheels in back. In the end, we found it was pretty easy to get it to go straight backwards (although it's hard to get it to change direction) and it's probably impossible to get it to go straight forward (although it's easy to get it to go in circles.)

I had to take it apart in the dark too and I guess it also took 30 minutes or so. I got back home and was somewhat amused to find that my feet got the dusty clay dirt all over them. It was very reminiscent of the playa, except it didn't burn or anything.

(For a while I was using something called the Coral project to host the video, but it has apparently gone away.)

(Click to play; 12MB)
Grainy, reduced-frame-rate, black-and-white, "NightShot" footage of The Bike With 2 Brains in the learning process of hell


Basic DC-DC converters

I found a website that described DC-DC converter basics. I took a crack at building a "boost" style step-up DC-DC converter (where an inductor is placed in series with a power source and the output side is switched to ground.) I managed to step 5 volts to 24 volts across a 1.2K load (using low-power components) for a current of 20mA or almost 0.5 watts.

I found that transformers work particularly well in the circuit — plus, the secondaries offer useful voltages as well. By switching to better transistors (i.e. 2N2222 instead of 2N4123) I achieved 38V out into 1.2K: 32mA or 1.2W. This looks very promising … now if only I could get it to work from 1 volt.

I measured across 51 ohms and got up to 9.3 volts out. The input current is about 0.46A at 5.7V, so that's 2.62 watts and the output into 51 ohms is 0.18A or 1.70 watts out, so it's about 65% efficient. Using a smaller torroidal inductor, I got 8.62V into 51 ohms or 1.47W with 5.82V at 0.40A in or 2.34 watts for 62% efficiency.

I started building one to work off 1.5 volts or so. At first I didn't get it to work. I rebuilt the whole circuit and got exactly the same bizarre result: a short-cycle square wave that seems to ring down. I couldn't get the thing to work. The capacitor on the NPN transistor seems to be running into negative voltage territory somehow … it actually oscillates, but the final output is a stilted square wave. I switched to a (possibly more stable) twin-T design which I managed to get to work with as little as 3 volts.

I thought that I could try using MOSFETs but I couldn't figure out how to get them to work.


LED's with bit modulation

I met a guy named Dave who referred me to an idea for driving LED's with a microcontroller using a shift-register and latch with a technique called "bit modulation." It's a derivative of pulse-width modulation except it's much better suited to driving multiple outputs concurrently.

In traditional pulse-width modulation (I'll assume it's all for LED's although it can apply to any averaged output) the LED is driven at full-brightness for some percentage of the time at a relatively high frequency (enough that the human eye's persistence of vision can't detect the blinking.) So, for instance, to create the illusion of 10% brightness, the LED is turned on for 1 unit of time and then off for 9 units of time. Usually the frequency of the wave remains the same and only the duty-cycle changes.

In bit-modulation, the desired modulation is assumed to be a binary value. The least significant bit (2^0) is read and the LED is turned on or off depending on its value for 1 unit (2^0 units) of time. The same is done for bit 1 (2^1) only for 2 units of time (2^1.) This continues for successive bits. The resulting brightness output averages to the value over 2^(n+1) clock cycles — the illusion works as long as the LED is on for [duty-cycle]% of the time and off for 100%-[duty-cycle]% regardless of how many times the LED is turned on or off during a cycle.

The huge advantage here is that a shift-register with a latch can be used to set the values for any number of LED's in a very short amount of time. That is, if you have X LED's, the same bit from each of the X LED's desired duty-cycles can be shifted in to the register, the latch can be triggered, and then the CPU will wait for (2^bit) time units until the next bit is loaded.

Unfortunately, I'm using a system where the red, green, and blue anodes are on three wires and the common-cathode of each LED cluster is brought back on one wire — so for X LED's I need 3+X wires. I dismissed the idea — although really cool — because it just wasn't practical for what I wanted to do.


Assembling the painted frame

I finally had a chance to put everything together with the office chairs and check it out. Some of the angles of the mounting points are off by a bit, but otherwise everything went together fine.

This is the only time the paint won't be all chipped.


Build the eye pupils

I assembled the pupils of the eyes with tubing, the pipe nipples I bought, the washer/nut assemblies that make the pupils themselves, and a couple clamps. Basically, I fit the end of the bolt that's welded to the washers that make up the pupil into the end of a short piece of polyethylene tubing. I used the pipe clamp to tighten it down and then glued it into the pipe nipple on the frame. I gave it a quick test with my LED light and it seemed that it might just work.


The final paint job

I added masking tape to the portions I don't want painted and brought them to Austin-Spencer Collision (2433 Brighton-Henrietta Townline Rd.) I talked with Mark who didn't give me a rosy outlook for getting done by Friday — I hustled to finish the frame so I could bring it to the ARTWalk (University Ave. from Atlantic to Merriman) Muse-a-Thon on Saturday, June 11. However, after he had his painter check it, he felt they could finish by Friday afternoon.

I took apart the wheels I had (the front rims are being painted) and reassembled the tires for the back wheels. It took a while to get the hang of assembling the wheels right — alternating the spokes the right way and all so it all fits together. I tightened up the spokes and got them "true enough:" they're still a bit warped, but good enough for what I need.

I used some office chairs I had and took them apart to use temporarily on the vehicle.

I stopped by Austin-Spencer Collision (2433 Brighton-Henrietta Townline Rd.) around 4 on Friday and by the time I left around 4:45, they still weren't done. Mark said he'd try to get there tomorrow morning around 8 and I could come by and pick it up, but that leaves me almost no time to finish building stuff, so I suggested we just call it off. I doubt that I could be ready in an hour from the time I get back with this stuff until the time that I could get to ARTWalk (University Ave. from Atlantic to Merriman) since I had to build the bike wheels, build the seat, and getting everything taken apart and put back in the car (the event was from 10 a.m. to noon.) There's just no way. I e-mailed some people I told about it and called it off.

On Monday I picked up all the parts. They look really good with the navy blue automotive clear-coat applied. Definitely much different than the scrappy metal I started with. When I assembled the front wheels, it took nearly 2 hours to make two wheels so I never would have made it to the ARTWalk event on Saturday.


Getting started with paint

I had found a metal cage in the garbage across the street so I cut it to a smaller size and welded it together. It's for the top of the rear shelf so people are tempted to use the shelf for stuff instead of riding on. I sanded it a bit and threw on a couple coats of primer real quick — it's already mostly painted.

I applied primer to the eyes and the top rails then drilled holes and tapped top rails for the brackets to hold the light tubes. I finish-welded the seat brackets, measured them (figuring I could build the seats while it's getting painted at the shop) and ground down the sharp edges.

I created a pretty decent battery holder out of the battery cage in a dead computer UPS but did a lousy job installing it. The solid metal shelf which is welded to the frame is a bad idea. It warped even more with the additional welding and I got really unhappy about it so I had to cut off the battery cage and the shelf.

I got the front end parts stripped of rust and primered. I spent the better part of a whole day painting and finished applying primer. I made hooks for all the parts so they can be painted.


Friends ride at my house

Peri and Kage stopped by and got to see me put the Bike With 2 Brains together. We tried it out and Peri described it as "riding a Spirograph." Courtney and Disa stopped by a little later and they rode it around as well.


Contact local musicians

I wrote a letter to some local musicians asking if they'd like to contribute some recordings to play on the vehicle. The letter (in general) is as follows:

I've probably mentioned it before, but here's some more detail: I'm building an art project for Burning Man (http://burningman.com) this year that's called The Bike With 2 Brains (https://jasondoesitall.com/bikewith2brains). Basically, it's a two-person vehicle where each of two riders pedals a unicycle wheel in front of them. Steering is accomplished differentially: to go straight, both riders need to pedal at the same rate; to go right, the left rider needs to pedal faster, etc. The back wheels caster-swivel, so that's the way to control it. I'm designing a lighting system and a sound system for it as well, and I'm looking for musicians who want to submit a piece to be included as part of what the sound system plays.

I apologize for the long e-mail … most of this is the same as what I'm sending to everyone else. I want to personalize each letter, so this paragraph is especially for you, [Recipient]! (har har.)

Also, if you're available, I'll hopefully have the frame built by June 11 and have it set up as part of the ARTWalk "Muse-A-Thon" that day from 10 a.m. to noon (I think.)

Anyway, to fill in a little more background about Burning Man, the setting is Black Rock Desert, Nevada for one week at the end of August. Essentially, Black Rock Desert is one big, flat, dry, windy, ancient lake-bed. Temperatures typically range from about 40 degrees at night to around 110 in the day. One of the two closest towns is Empire which is the home of U.S. Gypsum who make drywall: the wind blows a fine alkaline dust just like drywall dust. There is no vegetation at all and, relatedly, no indigenous animal life either.

Much of the activity as at night. As I mentioned, this year is a new moon, so at night, it will be pitch black, revealing more stars and galaxies in the sky than you can hope to count in ten lifetimes. There are very few formal rules, so it's a true test of anarchy. Despite there being around 35,000 people this year, it's easy to find yourself alone: the encouraged standard is laissez faire, so while you're free to do whatever you please, the flip-side of that apathy is that there's nothing you can do to "be interesting" — you are simply yourself. Also, there is no commerce allowed: the prevalent philosophy is a gift economy wherein you are allowed to give things to other people — however, there is no obligation to give anything away as in communism, so you've got to play nice with others.

My project will be one that anyone can ride, so I need to get people interested enough to ride it on their own. This is where you come in.

I'm looking for musicians to compose music for the vehicle. Thematically, I'm simply looking for sound to attract people and entice them to stay. The nature of the vehicle and the interaction of the riders will involve synchronized motion (FYI, bicycle pedaling is typically comfortable between about 40 and 90 rotations-per-minute) as well as agreement, teaching, learning, dialog, conflict, and argument. Feel free to interpret at will.

I plan on including a track of my own that I'm tentatively titling "New England Dusk." It'll be some combination of simulation and edited outdoor recording of the sounds of dusk around here … rather, the version of dusk _I_ remember … spring peepers, crickets, blackbirds, crows, and probably some cicadas. I figure it'll seem familiar yet wildly out-of-place at the event.

The only formal limitation I'm placing on content is that it include no lyrics: that is, instrumentals, or non-intelligible vocalizations are okay, but I don't want the songs to tell a story in words. I'm asking about 7 people to submit a piece and I've got 60 minutes total, so while any length piece is appreciated, a 50-minute masterpiece might not be included. I'm going to be using an MP3 player and I'll do my best to maintain pristine fidelity, but the format is limited. Also, the final output will be _monophonic_ so differences between stereo channels will be completely lost. Finally, keep in mind that the sound system will have limited capability to reproduce low frequencies and it won't go very loud (typically around 1 watt [which is louder than you'd think.]) I'm using car-stereo speakers, so as a reference, fidelity will be similar to a good quality boombox.

I had originally wanted to synchronize each song to a particular light pattern, but I decided to drop the idea because it would be too hard to do with the parts I'm working with and because it's a nightmare of organization: setting deadlines and making sure I have time to compose a light show — yuck. Thus, my absolute deadline for getting music in place on the vehicle is sometime in late August. However, I'd appreciate it if you can get back to me with something by early July through August 1 (at the latest) … adjust as necessary to fit your own procrastination scheduling.

Please let me know if you'd like to help out or if you've got any questions.