[Engineering] – Bullet flight sensor – circuit design

Continued work on the bullet flight sensor electronics. Dad had suggested that I research a “monostable vibrator” circuit, and to look at the 555 timer IC, so after some tinkering and math, here’s my first draft circuit diagram:


Dad (a retired electrical engineer) had given it his blessing, so the next step up would be physically prototyping it. Looks like I’ll be placing an order with DigiKey or Jameco or some other online electronics component vendor.

While the circuit components are enroute – and they will be breadboarded up first – I’m going to try my hand at learning Eagle, a CAD design software. The circuit is simple enough that I can probably etch it myself using laser transfer paper, but I might also just job it out to someone like BatchPCB.com and deal with it that way. It’ll all depend on the mechanical fabrication lead time as well as other project loads.

Meanwhile, mechanical design needs to be refined a little bit. These are current CAD model screenshots:


Here the unit is partially disassembled to change batteries.


Here’s a top view looking straight down on the circuit card, with the detector barrel rendered transparent.


And finally an isometric view of the unit assembled.

Mechanical details for the battery contacts, as ewell as lead-in for the slots, needs to be integrated. Then it’s a matter of generating a file to drive Dave’s grandparent’s laser engraver to cut these acrylic parts!

W00t, can’t wait! :-)