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A project log for Coil Gun/Gaus Cannon

A device that uses electricity to propel a projectile at a significant speed.

jeff.ballard.86jeff.ballard.86 06/17/2014 at 18:060 Comments

I ended up using 2 boards, because I ended up making changes to the optical gate circuits after I had sent off for the main board.  Good news is that it was easy to just make a slave board for that portion of the circuit.

I made a few mistakes when making the main board:

1.  The three mosfets in a row needed a 10k resistor between pins 1 and 3.  I fixed this buy just soldering directly to the pins from under the board.

2.  The blue cap in the middle right, the net wasnt connected for the positive lead.  Luckily it was close by, so I just bent the lead over and soldered it to the appropriate place.

3.  The Atmega168 foot print was way messed up, it was almost double the width as it should have been.  I was able to fix it by using a large dip socket (with the center cut out) and manipulating the leads into the proper orientation.

All of these mistakes could have been caught if I had only just printed the board traces/footprints out and visually inspected it and placed certain parts on top of their foot prints.

There may be other mistakes, im new to designing my own boards, but this one functions as intended (so far.)  I also need to order a variety of connectors because what im using is just a PIA.

Upcoming maybe today, at least within the next week:

A friend donated a 27" CRT TV for parts with the request that I destroy the tube is a spectacular manner.  So I figured, why not shoot it with the coil gun.  Once set up and filmed I will post here for your viewing pleasure.

I plan on testing projectile speed with different voltages, Im thinking that as Ive increased amperage, ive exceeded the capabilities of my projectile to absorb the forces applied to it from the coil.  I can control the amperage (and hopefully magnetic field) by changing the voltage.

At some point a test rig to test fire a 1" diameter slug, just for the hell of it.

And as always, thanks for viewing, and let me know what you think.

-Jeff

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