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This is the bench where the original prototype was bread boarded.
The first design for the altimeter incorporated an IR link to a Palm Pilot for data transfer. This
seemed like a good idea at the time, however, for field use, the IR port was often swamped by
the ambient light. |
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Here's a close up of the bread board on the left and the
first hand etched prototype boards on the right. The piece toward the top is the battery holder,
the middle portion is the microprocessor board, and the bottom board is the IR section. |
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This is a close up of the etched board by itself. Battery holder on the right,
microprocessor board in the middle, and IR section on the left. The pen is included for scale.
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This illustrates the first prototyped enclosure for the altimeter, including newly etched
and unpopulated boards. The enclosure was machined from
clear acrylic which was an unfortunately brittle choice of material, because when the first test flight failed to eject
the parachute, the entire altimeter shattered on the frozen ground. (polycarbonate is now the material of choice!)
After I collected the assorted pieces of wreckage, I powered up the microprocessor and was still able to download
the ill fated flight data. Gotta love flash memory!
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The next version of the enclosure was molded from polycarbonate.
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And then, after redesigning the circuit board for a serial com link and
discarding the IR link, the enclosure was redesigned again...to take on it's final form (top left). Bottom left
of the image is the original breadboard, bottom middle is the first prototype, bottom right is the final prototype,
center middle is the production version.
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Once the board design was finalized, then it was time to begin fabricating test and
programming fixtures. This is the unit that I use to trim the offset resistors and program the microprocessor.
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Once the altimeter is completely assembled, it's bench tested in a very sophisticated, calibrated
altitude chamber...yeah, it's a Ball canning jar. The syringe assembly on the lid, makes it very easy to "dial" in different
"altitudes".
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