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Thermoelectric Cannon Construction

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Plasmaniac

Tue Sept 19 2006, 05:28PM

Registered Member #206 Joined: Sat Feb 18 2006, 03:17PM
Location:
Posts: 72

My plasma railgun is a etg/rg fusion, actually

I don't dare putting some water in there because it nearly explodes without it (@3kJ). My rg3 design will have a way stronger construction, so I might try that in ~2 weeks (holidays :D).

We've been messing around with a ~500J acetone etg at the german teslathon. Using an alcohol for an etc might be better because of the lower boiling point. Also, it's very important that it doesn't conduct (for my railgun, I never use switches, just injectors for projectile and trigger electodes for plasma railguns). Light effects included xD.

Wilson

Tue Sept 26 2006, 02:27PM

Registered Member #78 Joined: Thu Feb 09 2006, 11:27AM
Location: Sydney, Australia
Posts: 133

Not many people have access to high voltage pulse caps FastMhz

I'll be giving this a try in 7 weeks time, after my exams are over, lol

FastMHz

Tue Sept 26 2006, 05:18PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Mine are computer grade electrolytics - I was just wondering with the relatively large number of coilguns and now induction launchers out there.

I look forward to your results...take video if possible

Wilson

Wed Sept 27 2006, 05:28AM

Registered Member #78 Joined: Thu Feb 09 2006, 11:27AM
Location: Sydney, Australia
Posts: 133

Does this still work if you use water spiked with a *tiny* amount of salt? It may allow for lower firing voltages. Just a thought....

btw FastMhz, I will soon have 2x 4kV 200uF caps along with my 500V 22500uF bank, with 3 months of free time....so this will be 'interesting'

FastMHz

Sat Sept 30 2006, 02:07AM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Are you going to wire those two 4kv caps together to make yourself a 3.2kj set? That should enable you to do some serious discharge experiments! I wonder what 8kv @ 100ufd would do when discharged into some water? I'll try your salt idea and see what happens - maybe I can get away with less power. I have yet to discharge a fully charged bank into the water gun as I'm afraid it'll just detonate.

Wilson

Sat Sept 30 2006, 09:06AM

Registered Member #78 Joined: Thu Feb 09 2006, 11:27AM
Location: Sydney, Australia
Posts: 133

I've been thinking about the water thing. I think it would be caused by the sudden dielectric breakdown of water (hence explaining the voltage required) which allow for significant current to flow?
The salt water thing might just ebb the charge on the caps away if the resistance is too high i think...

btw FastMhz, do you need hearing protection when discharging your bank?

Effilcdar

Sun Apr 22 2007, 07:03AM

Registered Member #655 Joined: Wed Apr 18 2007, 10:23AM
Location:
Posts: 14

I agree that a spark plug should be terribly ineficient. I would recomend removing the outer terminals so the center cap of the spark plug can jump directly to your barrel.

FastMHz

Tue May 01 2007, 01:32AM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

WOW...has it been a long time since I posted here! To answer some of the questions:

1. I did manage to get a successful firing of my ETC...I have a video on YouTube showing all my latest experimentation:

2. Yes, hearing protection, and eye protection, are an absolute must when discharging my bank. When all works properly, things are usually quiet - except the induction launchers make one heck of a bang. But when something goes wrong, like a wire detonating, or solder joint vaporizing, it's like a 12guage in a closet. Scares me silly!!

ConKbot of Doom

Tue May 01 2007, 12:16PM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

When spark plugs are being used, is it in the normal arcing from the tip to the ground on the same plug? or are the plugs being positioned close enough, and having the ground terminal removed so that they are arcing from one plug to the other? This has gained my interest some, and I have a box full of PFCs, some 1200v IGBTs, and some mosfet drivers begging to have something done with them.

FastMHz

Tue May 01 2007, 05:27PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

I've been using a single plug soldered into the end of a copper pipe....two plugs opposite each other is an interesting concept that I may try.

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