Figure 1 shows the generic display. Subsystems are identified by color. In red, there is a wooden frame constructed like the wall of a house, 6 feet by 6 feet. It needn’t be as strong as a house wall, just strong enough to withstand lots of force applied on the crank by people, and the weight of the mechanisms and displays. As a flat unit, this is held up by being connected to the other two displays along the vertical edges. The placement of 2x4s in the structure is related to the placement and size of the other subsystems. Some strengthening member is probably needed to prevent parallelogram instability, which can come from the decorative panels described below.
In blue there are the mechanical assembly and the display panel. The mechanical assembly contains the precision mechanical components that need to be in alignment, such as crankshafts, gears and chains, generators, flywheels, cams and such. This assembly is made of metal, possibly Unistrut (a versatile steel U-channel system). The transformation of human arm energy into other forms occurs here. It bolts on to the wooden frame. This assembly may include protective covers to prevent users from getting caught in gears. The display panel contains the displays to look at and interact with further. It is the most variable among the subunits, and is developed along with the mechanical assembly (thus they are the same color in the diagram). This panel also bolts to the frame. It is probably based on a plywood panel painted or covered in some way, with a dark color to foreground the things in front.
In green are the text, title and decorative panels. The title panel announces what this is, and signals that it ought to be fun to interact with. It should appear professional, to inspire confidence (even if that’s only a trick). The style of the title and decorative panels is not clear right now, but they ought to take advantage of the extra information that can be conveyed by style. The panels are indicated as having non-square sides, to break up the squareness of the rest of the assemblies. They are thin painted plywood, though the decorative panels can also be used to add strength to the frame if they are thicker wood.
The text panel contains the explanation of what to do and what it means. There are several paragraphs of text and diagrams that need to be on this panel, so it is probably a laminate of wood, printed text and some transparent over coating. Last year I attached large computer-printed pages to plywood with spray adhesive and then stapled on some clear vinyl sheet for protection. This was cheap and robust against damage, but could be improved upon. The inks in ink jet printers are water soluble, so there needs to be something waterproof over the text.
All of this can be specified so that the various parts can be manufactured separately and then bolted together. It is probably desirable to transport the various pieces separately, to prevent damage in transit, and then assemble on playa. All the pieces should be collected together in one place before transport, as we have an agreement from the organization that they will transport this material. The parts that need to be developed most closely are the mechanical and display panels, and the text panel needs to be finalized after the display materials are substantially completed. Other parts can be made independently.
Specific displays
Stake whammer
The crank is turned, and there is a sledgehammer on the end of an arm that whams a stake into a friction mount. As the crank is continuously turned, the hammer repeatedly hits the stake until the stake is at a stop, at which point the user flips a lever that releases the stake back to its original height. There is a balance here between the hammer weight, height, stake friction length, clamping force, friction material etc. This all needs to be experimentally developed.
I show in the diagram the simplest mechanism for demonstrating two different elevations for the hammer before it’s released: a cam with two diameters that just alternates between heights. It would be more satisfactory to allow the user to vary the height in steps or continuously, and to wham away at one height until they try another. It is important to be able to compare the effect of different heights, as this represents different stored energy and increments the stake pounds down. Of course, you can have less energetic taps but it takes more of them, versus fewer stronger taps. This indicates there is a fixed amount of energy needed to get the stake down, not accounting for frictional nonlinearity. It ought to be that twice the height of the hammer is twice the motion of the stake, but I’m not actually sure of that. The point is that the particular mechanism needs to be decided on, based on considerations of reliability, adjustability and cost.
Generator
This display owes a lot of inspiration to the guy at the Greenhouse preview with his pedal generator (www.los-gatos.ca.us/davidbu/pedgen.html). He had a pedaled generator with a large flywheel, powering various appliances through an inverter, and regulated with an ultracapacitor. For this energy display, a hand crank will provide the interface, though a flywheel is a good idea to smooth the power and to show energy storage. The flywheel drives a generator that can power whatever the user selects, using a large selector switch. For instance, let’s say the user cranks up the flywheel and connects the incandescent lamp. The flywheel runs down quickly. If the user does the same with the compact fluorescent, the flywheel will take longer to run down. Or, the user will have to crank continuously with less effort expended.
A variety of home appliances can be shown, along with an assortment of lights. The idea here is that the user gets a feel for the amount of power used by each. Are these devices actually “labor saving” or is that just an illusion? Some tests may be best done with two people, one to crank and the other to activate features of the appliances. There should be one 750W one, which a person can’t work because it would take a horse. If there is any electrical energy storage in the inverter, a pocket calculator would work for hours just on that. then the user can suck it down in seconds with an incandescent light. There needs to be a voltmeter. Choice of the appliances will be fun, so the operation should be too.
Rube Goldberg device
The aim here is to translate between as many energy forms as possible, while still being able to work them all. This is not easy, as each is inefficient. Some energy storage in different forms is good to show, and may be necessary just to get the next stage to go. In the figure I show a crank operating a hydraulic pump that drives a corresponding hydraulic motor, then gear reduction, then AC generator, transformer, water pump to raise weight of water, water generator, LEDs to solar cells, sound energy from speaker to speaker (after an oscillator), storage in a capacitor, then finally an EL display of a dancing alien. Something like that, but more is needed. A tour through a good surplus store, maybe two or three would provide inspiration.
The text panel can provide explanations, but the particular components should be labeled with what they are and what they’re doing, what kind of energy etc. Stuff to see is best, such as pumping water to a height, as opposed to charging capacitors. Storage of energy in elevated water suggests hydroelectric plants. A closed-cycle “steam engine” of some sort would be excellent, though the problem with thermal energy flow/storage is that it’s slow and subject to ambient temperature. The user should have fun getting things to operate, and noticing that as they apply effort, there are more and more things that “light up” due to the fact that energy is stored and is getting released at some threshold. You crank the Mouse Trap crank and things happen in sequence, not all at once. In this case, groups of things are all at once, separated by energy storage which provides time delay between the groups.