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LAN_403

Bust_A_Cap

Sun Jun 29 2008, 07:46PM

Registered Member #1561 Joined: Mon Jun 23 2008, 07:58PM
Location:
Posts: 25

Wow Nik those are pretty sweet, did you try and take some of the leftover sand off, or is it to fragile to try polish out?

Dr. Dark Current

Sun Jun 29 2008, 08:02PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Nik wrote ...

I used dry sand and a 4mot stack with resonant caps. Heres a video and photos of what I got.

That is really cool Nik. How wet was the sand? I must try that myslf too.

Just one question (I commented on your video too) how comes your capacitors did not explode? You are supposed to use 8 caps (with 4 MOTs), not 2.

Kizmo

Sun Jun 29 2008, 08:56PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

MOCs can take a hell of a lot more voltage than just 2kV.

Nik

Sun Jun 29 2008, 09:22PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I was only 2 of the mots in use not all 4, sorry about the confusion. They don't don't clean up at all (they just fall apart) and after sitting undisturbed for about 3 months they disintegrated back to a pile of sand and some hunks of black and green glass.

Dr. Dark Current

Mon Jun 30 2008, 08:53AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Kizmo wrote ...

MOCs can take a hell of a lot more voltage than just 2kV.

yes, but in the "classic" resonant circuit they see up to 5kV peaks, if you use just one it will se 10kV peak.

Nik wrote ...

I was only 2 of the mots in use not all 4, sorry about the confusion.

So may i ask how did you connect 2 MOTs with just 2 caps?

Edit- sorry for OT, I will to make these myself too and post the results soon.

aonomus

Mon Jun 30 2008, 12:34PM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Maybe you could blowtorch the surface of that to cause the sand ontop to turn to glass, only downside is the expansion/contraction might cause the whole thing to explode.

J. Aaron Holmes

Wed Jul 02 2008, 02:28AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Well...

I tried making fulgurite like Nik, but using 15.6kV at about 200mA. The paving sand produced a cool-looking orange arc, but in the end the sand was just very hot and dry

<NapoleonDynamite>DaaaAAAAAaaang!!</ NapoleonDynamite> If only I hadn't used up the wire in my 500ft-spool-of-wire ballast, I'd have been able to run up to bigger kVAs, but alas... Time to get working on a new ballast!
Sand Small

I tried a cement tile just for kicks. It produced some buckshot-sized balls of rootbeer-colored glass which were pretty boring. The glowing-hot current path visible on the size of the tile was mildly amusing, however:
Tile Small

Try try again!

EDIT: Trying again, this time with some white, quartz-looking sand. Also tried burying the electrode in the sand just slightly. Not very precise science, since I'm not yet sure which of these things really helped, but it did work much better. The sand pile glowed white-hot, and in the end I had some fulgurites. They seem quite robust. Note that I actually made two of them; the final picture is not a broken one

Cheers,
Aaron, N7OE

Dr. Dark Current

Wed Jul 02 2008, 07:32AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

I tried it with 2kv at 2amps, it buzzed loudly but the sand was just dry at the end (like Aaron's first try).

How much is optimal to damp the sand? And how much voltage and current is best to use?

aonomus

Wed Jul 02 2008, 08:15AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Could the difference be Nik's sand vs Aaron's sand? Everyones sand seems fairly 'pure' other than Nik's, perhaps regular playground sand might contain more iron/moisture/conductive particles vs clean sand. Fulgarites are made by melting the sand turning it into glass, and supposedly if the arcs pass through the gas around the sand, it wouldn't heat up as quickly.

It only strikes me after writing the above paragraph, that Aaron's sand container had maybe only 1" deep sand, but Nik's sand could have been much deeper.

J. Aaron Holmes

Wed Jul 02 2008, 03:01PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

aonomus wrote ...

Could the difference be Nik's sand vs Aaron's sand? Everyones sand seems fairly 'pure' other than Nik's, perhaps regular playground sand might contain more iron/moisture/conductive particles vs clean sand. Fulgarites are made by melting the sand turning it into glass, and supposedly if the arcs pass through the gas around the sand, it wouldn't heat up as quickly.

It only strikes me after writing the above paragraph, that Aaron's sand container had maybe only 1" deep sand, but Nik's sand could have been much deeper.

Yes, my container was very shallow; the little sand piles I was making were only just over an inch tall.

All of the examples above are quite unlike lightning, of course; we are trying to make up for lack of instantaneous power by maintaining an arc for a number of seconds. It would be interesting to see how the results differ if somebody like TDU, who has a huge high voltage capacitor bank, were to do a pulse discharge into some sand. Heck, he's probably done it before and just hasn't gotten the pictures posted yet

Cheers,
Aaron, N7OE

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