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Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
So for my upcoming railgun project, I was wondering how powerfull of diodes i should get to protect the capacitors. The only way i see to do it is mesure the resistance and inductance of everything, which i have no way to mesure acruatly. I was planning on 5kJ at 450-500V. What surge current should i look for? im leaning toward 1000V diodes to be safe. What saftey factor should i leave?
There is also the problem of EM pulses, how can i shield from these? i want to record it.
Registered Member #1320
Joined: Sat Feb 16 2008, 01:31AM
Location:
Posts: 67
Low inductance in a railgun means you shouldn't need a protecting diode (I didn't and my cap bank still is fine) As for EMP, I didn't experience any problems with it and I had a microphone only about 12" away from the rails. If your doing this for a science fair I would strongly suggest something less lethal.
Registered Member #1262
Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451
For EMP protection you'll need a Faraday cage, basically just grounded mesh screen enclosing everything. Also remember that the magnetic field falls off with the square of distance, so keeping everything several feet away is good.
Donno about the diode, depends on the resistance and inductance of the gun, which I have no idea of, seeing as I havn't built a railgun yet.
Registered Member #1262
Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451
Well yes, if you wrap the equipment like a freakin mummy! However I would be inclined to agree with ea6b607's statement that a faraday cage is not essential. Keeping all the equipment 4+ feet away should be good, but IF you really want to keep things 100% safe, just use Al foil and some type of mesh for windows.
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protecting from ringback and EM pulses
