Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

If you know anything about Railguns or Capacitors, please read

If you know anything about Railguns or Capacitors, please read


  #1  
Old 08-17-15, 02:09 PM
SolarFlare's Avatar
Member
Thread Starter
Join Date: Mar 2015
Location: Canada
Posts: 33
Upvotes: 0
Received 0 Upvotes on 0 Posts
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?
 
  #2  
Old 08-17-15, 02:16 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 36,608
Upvotes: 0
Received 9 Upvotes on 8 Posts
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?
 
  #3  
Old 08-17-15, 02:20 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
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.
 
  #4  
Old 08-17-15, 02:32 PM
SolarFlare's Avatar
Member
Thread Starter
Join Date: Mar 2015
Location: Canada
Posts: 33
Upvotes: 0
Received 0 Upvotes on 0 Posts
(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
 
  #5  
Old 08-17-15, 02:44 PM
SolarFlare's Avatar
Member
Thread Starter
Join Date: Mar 2015
Location: Canada
Posts: 33
Upvotes: 0
Received 0 Upvotes on 0 Posts
(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.
 
  #6  
Old 08-17-15, 04:17 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 36,608
Upvotes: 0
Received 9 Upvotes on 8 Posts
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.
 
  #7  
Old 08-17-15, 05:17 PM
SolarFlare's Avatar
Member
Thread Starter
Join Date: Mar 2015
Location: Canada
Posts: 33
Upvotes: 0
Received 0 Upvotes on 0 Posts
(Ray) Cant discharging a cap by short circuiting it cause it to explode?
 
  #8  
Old 08-17-15, 05:30 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 62,035
Received 3,415 Upvotes on 3,063 Posts
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 ?
 
  #9  
Old 08-17-15, 06:01 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
To add to PJ's suggestion you could wire a momentary contact switch in series with the light bulb.
 
  #10  
Old 08-17-15, 06:04 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: United States
Posts: 13,753
Received 672 Upvotes on 570 Posts
Most BB's are copper plated steel. I always used a magnet to pick them up.
 
  #11  
Old 08-17-15, 06:22 PM
SolarFlare's Avatar
Member
Thread Starter
Join Date: Mar 2015
Location: Canada
Posts: 33
Upvotes: 0
Received 0 Upvotes on 0 Posts
(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
 
  #12  
Old 08-17-15, 09:56 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 5 Upvotes on 5 Posts
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.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: