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StanO

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Magnetic switches are great space savers. If you launch from a steel tower, however, be sure to test that it does not turn off your switches as the rocket exits the tower. There was enough magnetic field at the end of this one to turn off both altimeters.
Thanks for this one. You may have saved my bacon on a future launch. And no, "bacon" isn't the name of the rocket. :)

And, thanks Chuck for the thread.
StanO
 

skydog

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the article, while informative, does not apply to the microcontroller chips used in the alitmeters. Early microcontrollers did not have any built-in protection that basically delayed startup of the micro until power was thought to be stable. They required a capacitor, resistor, and typically a diode on the microcontroller's reset line. When power bounced off the diode would drain energy from the capacitor and when power bounced on, the capacitor would charge through the resister. If the reset pin managed to reach a threshold voltage, the microcontroller would start at a boot location and run code.
For those handy with a soldering iron, a large capacitor (470 uf or so) across the power leads after the switch would help.
I also drop my altimeter bay on the workbench a few times, in all orientations, to subject it to many Gs and see if I have any bounce.
 

paulfecht

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Recessed charge wells... that is brilliant!
Can you elaborate on the brilliance of this method? Is it because the recovery hardware won't hit the charge wells? I wonder how they are packed and secured? taped off?
 

GlueckAuf

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My redundant (and recently successful) L3 avionics bay features dual Featherweight magnetic switches at opposite corners, apogee event-only altimeter function (dual serial-joined JLCRs handle the main event), and center strain-relief standoffs to transition thin altimeter wires to heavy-duty lamp cord running to the bulkhead ematch terminals.

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