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Registered Member #3282
Joined: Wed Oct 06 2010, 05:01PM
Location:
Posts: 224
Can you guys imagine what it would be like to own and build a high voltage capacitor that can store 1 megajoule and up of electric energy? I am thinking of a three layer Mylar film capacitor made up of 20 mil sheets stack three deep in between the aluminum foil layers. You would build your own rolling machine buy bulk from dupont and Reynolds aluminum foil. for casing you would go to the sewer district contractors and order a piece of 4 foot wide PVC pipe. With this level of power you can make a decent coil gun with hypersonic projectiles, megagauss fields for transient MRI gold prospecting. lots of fun waking up the neighbors as well.
Registered Member #4081
Joined: Wed Aug 31 2011, 06:40PM
Location: UK
Posts: 139
What would everyone else build with a capacitor this large? Looking at my disposable camera now thinking it would take years to charge a cap like this . . .
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Lets see... a quick calculation made with deepfriedneons plate capacitor calculator says
With PVC dialectric, I would need 13700 plates with 0.01 mm distance with an size of 300 x 300 millimeter to get 5000uF, that at 20kV is about a million joule.
Registered Member #3447
Joined: Fri Nov 26 2010, 11:10PM
Location: North Jersey
Posts: 97
I think jnbrex might be confusing "dielectric strength" with "dielectric constant". Even if jnbrex meant "dielectric constant", we know that capacitance increases with the dielectric constant (C=k*e0*A/d), ceteris paribus.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
jnbrex wrote ...
Having a material with higher dielectric strength would decrease the capacitance proportionally, so it would not be any better of a material.
Dielectric strength doesn't affect capacitance at all on it's own as long as the capacitor isn't breaking down, it just allows you to use thinner isolation before it breaks down ... and since capacitance is proportional to 1/d that gives you greater capacitance per volume.
If I was going to spend the time DIY'ing a big pulse capacitor I'd use BOPP packing foil ... also I'd build it as a MMC, trying to make one absolutely huge one is asking for a lot of heartache in the case of catastrophic failure.
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
hi Microwatt, I have seen mega joule banks of caps that take up a room. unless you have a Quarter million and a facility for the caps you wont get there. Theas types of facilities can pose a explosion hazard and envaulve things like interlocks. if you want to play with cap get a hand full of electrolytics and a SCR and wind a coil and make a coin poper. I have thought of making a can crusher
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megajoule capacitor
