Electronic – Feasibility Question and Advice on CAD software

cadpcb-fabricationprototyping

enter image description hereFor a hobby project I have bread boarded, I am considering using a pair detectors that operate as a single use physical barrier. When hit by a projectile, a trace is broken allowing +5VDC to to trigger a flipflop that is part of my gate logic for a counter-timer.

I have envisioned this detector as a thin adhesive sticker with a thin copper trace embedded in it that forms a simple pattern to cover the area, zigzaging across the surface. Similar to the passive RF sticker tags used by retail stores for antitheft.

My questions are:
1) Will it be practical to have a manufacturer print a batch of these things for me?
2) I've never used CAD software before, is there a suggestion for a free CAD program, that doesn't have a huge learning curve for this type of project (I'm a linux guy but thinkning W7 is more likely here ) ?

EDIT: Photo diodes are a great idea, and I will likely try them and ask questions in a separate thread. The break-able trace allows for more configurations and keeps slew rates ( and other rates ) small. I plan to use a very small distance to track the velocity of said projectile, like 1 or 2 cm.I have a 10 Mhz clock for my timer.

EDIT2: I should have added a current limiting resistor to the diagram so as not to start a fire with the trace…but I think you get the idea from this diagram.

Best Answer

Using metal Christmas tree tinsel used to be common for this sort of thing in physics labs; then photo gates got cheap, tinsel feel out of favor as a decoration, and modern varieties may not be conductive anymore anyway.

For a disposable item like this, you might want to investigate some sort of carbon-based conductive printing rather than a metal circuit board process or silver-based conductive ink which costs a small fortune. You don't need anything nearly as conductive as a normal circuit board, as you only need to detect if the connection is still intact or not.

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