2013-09-14 Kickoff Meeting

Outstanding issues/questions

  • Vet basic design. Anything missing / incorrect?
  • We need to spec out and acquire the Mosfet transistors that we'll use for the radio and nichrome wire.
  • We need to find a piezoelectric buzzer that will run on 3.7V, and use less than 40ma.
  • Do we need a resistor or something else to bring the LED into Spec?
  • We need to weigh all our provisional components. How much lift do we need.
  • Balloon options
    • Mylar + Helium. Can we find a cheap source on campus?
    • Mylar + Hydrogen. We could make some.
    • Hot air. We'd need to craft the balloon from very light materials.

Summary

  • Circuit looks good!
    • We'll drive the LED and buzzer from the Atmel directly
    • Atmel Tiny 13 can drive approx 40mA per pin
    • Top power draw of Atmel is 200mA
    • Need to find a TO-92 package MOSFET/BJT that will work.
    • Need a 0.1uF bypass cap for the Atmel
    • The Alinco DJ-C4T radio is about 300mA on TX, 70cm band.
  • Parachute
    • Total weight of system
    • Desired landing speed (usually 15 ft./s)
  • Gas system
    • Can we get a helium source?
    • Are we going to make hydrogen from drano + Al foil for fun & profit?

Experiments to Run

  • Test nichrome trigger on battery with MOSFET/BJT
  • Test nichrome trigger's capability to burn the nylon string
  • Test the shock load of the nylon string.
  • Get a dummy weight and drop a parachute off of some building (this is totally not sketchy).
  • Test the radio under repeated power cycling (will it hold programming?)
  • Atmel Tiny programming/debugging
  • Test balloon lift properties with various gases.
  • Foxhunt the Alinco to test range/signal strength, etc.

Action Items (By 9/19)

  • Jon
    • Get appropriate transistors!
    • Get a buzzer that's obnoxious and runs on < 40mA @ 3.7V
    • Get a 0.1uF cap
  • Matt
    • Parachute calculations in spreadsheet for reference
    • Parachute diameter, landing velocity, mass of system
  • Mike
    • Total weight of system
      • Alinco
      • Atmel circuit stuff
      • Battery
      • Nichrome, etc
      • Container (bottle)
    • Work on containment/bubblewrap system.
    • Program the Atmel to do cool things
      • Twiddle a pin to make more sounds
      • Turn on/off the radio
      • Time the nichrome trigger
  • Stephen
    • Look at gas/balloon sources
    • Optimize gas sources on pricing/availabilty/# of launches.
    • Check out airgas, a local? supplier.
  • Jules
    • Get nichrome wire
Last modified:: 2013/09/23 09:05