1. The design at present
2. Next week
3. Field testing in Uganda
1. The Design as of Now: These parts might be hard to visualize, so I included a rough paint file to show them.
Horizontal to Vertical Joint - This joint has two degrees of freedom, one that rotates the horizontal beam up and down and one that rotates around. A bicycle hand brake mounted on the lamp head locks and unlocks the vertical joint. The vertical beam is capped with a U-shaped piece spanned by an axle that goes through the middle of the horizontal beam. Connected to the axle is a dumbell spring-loaded clamp. One end of this clamp is welded to the inside of the vertical beam, the other is connected to the bike brake wire. When the bike break lever is pulled it squeezes the two clamp pieces together, which releases the clamp from the axle. For the joint that swivels the horizontal beam around we're planning to make a joint by taking two tubes, one slightly bigger than the other, inserting them partway into each other, cutting slots in the larger one and putting tabs in the smaller one. This allows the smaller and larger tubes to rotate relative to each other with the tabs keeping them together. I'm slightly worried this will have too much friction, but I could just be paranoid.
Electrical - Since we're on a tight schedule and are a bit light on electrical expertise, I think we're best off if we just wire the LED heads together in parallel and hook them up to a battery pack made from the AAAs that came with the lamp. We can wire them to a rocker switch on the lamp head so we can turn all of them on and off at once. We can toss the batteries in the counterweight on the horizontal beam.
Lamp Head - We still don't have a final solution for this yet. I suggested using a shallow tupperware bowl and cutting holes in it for the LEDs. Mike suggested using a hubcap, which we can take a look at when we go to a junkyard to look at parts.
Head Joint - We're planning to use a car's rear view mirror joint. After playing with the one in Elliot's car, it seemed stiff enough. As a backup we could use a simple friction tightened hinge or a friction tightened ball and bracket (see the soldering stand in the project room for that joint).
Base - Just 4 legs on casters. We talked about having the rotation joint here instead of at the horizontal to vertical joint, and we still may.
2. Next Week
We need to finalize our structure and then get a part list and dimensions. Who is available on Monday to do a final design review? After that we can break off into teams and start getting parts. A group of us should head to a junk yard to check about getting parts there. Did anyone go on the junk yard trips earlier in the year?
We need to get the rest of the LEDs from Home Depot. Someone with a car will need to pick those up (I don't have a car). They'll cost ~$200 and you will be reimbursed in about a week. If someone is willing to drive but can't shell out money for them, let me know and I can go with you to front the bill.
We're pretty close to the point where we can start slapping things together, lets try to start building before the end of the week.
3. Field Testing in Uganda:
The plan is to get our lamp built and tested before April 7th, when we'll send our lamp with Abigail (the applied physics grad student most of you have met). She'll be in Fort Portal, Uganda for a couple weeks and will take our lamp to some clinics and show it to people working at a local technical school. This is a great chance for us to get feedback on our design so we can work on making the next iteration much better.
Steve
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