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If you know anything about Railguns or Capacitors, please read

If you know anything about Railguns or Capacitors, please read

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Old 08-17-15, 02:09 PM
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If you know anything about Railguns or Capacitors, please read

Hello all. I am trying to build a 3 1/2 inch railgun that fires small copper bb's used in a bb gun. For this, i am going to need a Capacitor bank powerful enough to make the railgun work, and also a way to recharge the capacitor bank. On youtube, i have learned how to charge individual capacitors at a time, but not an entire bank of them. I am also wondering if i can discharge capacitors by dipping both the terminals in a puddle outside simultaneously. Dont worry, when handling capacitors i am aware of the dangers and i always wear latex gloves so that i have a much lesser chance of being killed. In summary, my three main questions are:

1. Is 469.6 Volts and 2149 uF enough to power this small Railgun?
This railgun is 3 1/2 inches long and i am planning on firing 4.5mm copper bb's. This is the amount of power i have so far from my capacitors.

2. Can i discharge capacitors by dipping them into a puddle?
Only the terminals, of course. I will be very careful not to dip the other parts of the capacitor into the water.

3. How can i charge an entire capacitor bank at a time?
...Any ideas?
 
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Old 08-17-15, 02:16 PM
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You are probably not going to get a bunch of help with this project from us. First, where will you obtain 469 volts? Charging the caps? I don't think you have enough experience with capacitive loads or capacitors in general to do this. Dipping them in water??? How will you disconnect the capacitor from your mechanism to do this safely?
 
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Old 08-17-15, 02:20 PM
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2. Can i discharge capacitors by dipping them into a puddle?
Why would you? Water is an a very poor conductor. The conductivity of the water if clean would be low. The typical way to discharge a capacitor is with the metal blade of a screwdriver with a handle that has been UL tested for it's insulation.
i am aware of the dangers and i always wear latex gloves so that i have a much lesser chance of being killed.
Only slightly less and not even that if there is a pinhole. You need cloves for high voltage work that are periodically tested to be sure they are safe.
On youtube, i have learned
Five of the scariest words I have seen written. Youtube is full of bad information written by idiots.

http://farside.ph.utexas.edu/teachin...es/node46.html

Capacitors are charged with a battery or a DC power supply.
 
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Old 08-17-15, 02:32 PM
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(Chandler) I would Discharge each one individually first, solder them together to make a capacitor bank. The bank will have wires with clips at the end that hook onto the terminals of the railgun
 
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Old 08-17-15, 02:44 PM
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(Ray) Thank you, very helpful. Also thank you for letting me know that disposable rubber gloves aren't gonna save my life... I'll try to get some ones that are specifically meant for electricians.
 
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Old 08-17-15, 04:17 PM
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During my Residential and Commercial wiring classes, I helped the rookies along, since I had done most of it before. Just brushing up. I had one smarty that thought he knew everything. While setting up a simple resistor,cap,wiring load, I tried to tell him what mF cap he needed. He brushed me aside and asked where the caps were. Knowing they weren't discharged, I pointed to the shelf. He found them. All I heard was a "POP" and knew he had a lesson learned.
 
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Old 08-17-15, 05:17 PM
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(Ray) Cant discharging a cap by short circuiting it cause it to explode?
 
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Old 08-17-15, 05:30 PM
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You can use a standard light bulb (50-100W) to discharge a cap.

I thought railguns were magnetic. How will it work with a non ferrous copper ball ?
 
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Old 08-17-15, 06:01 PM
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To add to PJ's suggestion you could wire a momentary contact switch in series with the light bulb.
 
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Old 08-17-15, 06:04 PM
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Most BB's are copper plated steel. I always used a magnet to pick them up.
 
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Old 08-17-15, 06:22 PM
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(PJmax) Thanks for the info, Also thanks Ray. Yes and no... Its kind of hard to explain. A coilgun or gaussgun is magnetic, and a railgun kind of is too but it doesnt have a magnet in it. When the projectile is in contact with both rails it completes the curcuit and the entire gun sort of turns into an electromagnet. This is very hard for me to explain.. I recommend you watch these videos
https://www.youtube.com/watch?v=AhdXa7nHODw
https://www.youtube.com/watch?v=pIF1...?v=QxXlCfCgdcY

(Tolyn) no problem, i will just find something else that is equally size and non-magnetic yet conductive
 
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Old 08-17-15, 09:56 PM
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We aren't going to do your homework/thesis for you. This has no useful purpose, you just propose a demonstration model. The US Navy has spent billions on this exact tech. It's out there, just go find it. JC, amusement parks have been doing the same thing for years.

You really don't understand railgun tech. There is no required contact between the rails and the projectile, its about a moving magnetic field.

I'm closing this tread as it is not a DIY type question.
 
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