Tuesday, March 10, 2009

New Ignition System, Part I

I currently have a pair of Estes Electron Beam 6V launch controllers. They work just fine for Estes igniters; the batteries last around 50 to 100 launches. However, they don't generate enough current to fire a hot-wire igniter (like the Quest MMX igniters) reliably, and they simply can't fire Copperheads. (Copperheads are Aerotech's igniters for small composite and reloadable motors, like the D21 for my machbuster and the 24/40 motors I plan to get. Quest's new Q2G2 igniters can ignite a few composites, but estes igniters cannot).
I'm building a new ignition system based a few guidelines:
  • Must be triggered by a standard Electron Beam Controller.

  • Must not require modifying my existing equipment

  • Must be cheap and use available components.

  • Must have at least 30 feet of wire so I can fire up to F motors safely.

  • Must provide 12V at several amps with 2 6V lantern batteries attached.

My new system is very simple. It consists of 2 lantern batteries, a 6V relay, and 30+ feet of wire, plus alligator clips to attach to motors. The relay coil is triggered by a standard launch controller. The 6V relay is the only special part; it costs about 3-5 dollars from catalogues or Radioshack, but I took mine off an old circuit board. That's what I call electronics recycling. The only drawback is that the test current thru the light bulb is enough to trigger the relay; I'll have to add about a 10Ω or 100Ω resistor in series with the coil. I tested the coil in its little box tonight; tomorrow I'll figure out the wires and clips. Because the wire I found in the junk box is 4-core wire, it'll be very easy to do clustering. That's another place where the extra current and voltage comes in handy.
I'll also draw up a simple circuit diagram.

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