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Any oppinions on spark gaps

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Sam

Tue Mar 14 2006, 06:23PM

Registered Member #227 Joined: Mon Feb 20 2006, 10:47PM
Location: Cambridge Ontario, Canada!!
Posts: 127

I'm gonna build a new Tesla coil. I have the HV power supply

and I'm just doing some calculations. I want to make a 2 foot secondary, 35 deg. primary out of 1/4" copper tubing, and some other neat innovations. But the one thing that has me stumped is the spark gap.
I dont know if I should go rortary(I'm broke) or statics series SG. I want to have a blown Gap(s) I have some brass bolts (Big) and I've grinded them to a point, they heat fairly quick (run off the MOT SPU) What do you guys think? I've searched google and some other sites including this one and I cant find much

Oh and I have no clue how to measure the amount of current my HV PSU can produce. My multimeter is fried and my other one only has a 400ma rating, my variac has only a 5 amp one so no calculations there. What to Do!

Thanks

Sam-0

HV Enthusiast

Tue Mar 14 2006, 06:33PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

the big question is how much power are you planning on running, and what power transformer are you using (NST, MOT, pole transformer, etc...)

Sam

Tue Mar 14 2006, 06:46PM

Registered Member #227 Joined: Mon Feb 20 2006, 10:47PM
Location: Cambridge Ontario, Canada!!
Posts: 127

If you look at the pictures you can see I'm gonna use 2 MOT's, and a "level shfter"(2 MO caps, and 2 MO HVR diodes) but I also plan on having 2 100Î©/100w resistors as current limiting

I'm nor sure how much power I want to be sucked from the mains... Hopefully I can run it on 120/60hz but that may pull to many amps, 220 may be its future.

any other info just ask...

EEYORE

Tue Mar 14 2006, 08:15PM

Registered Member #99 Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637

benguy wrote ...

If you look at the pictures you can see I'm gonna use 2 MOT's, and a "level shfter"(2 MO caps, and 2 MO HVR diodes) but I also plan on having 2 100Î©/100w resistors as current limiting

I'm nor sure how much power I want to be sucked from the mains... Hopefully I can run it on 120/60hz but that may pull to many amps, 220 may be its future.

any other info just ask...

Wouldnt 220v pull more amps than 120?

Matt

vasil

Tue Mar 14 2006, 08:20PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

If you are broke, but have big brass electrodes, the major option remains the static gap. using the static gap you can find the best setup to ballast the HV source. After that you can evoluate to a RSG.

Sam

Tue Mar 14 2006, 08:28PM

Registered Member #227 Joined: Mon Feb 20 2006, 10:47PM
Location: Cambridge Ontario, Canada!!
Posts: 127

mattrg2 wrote ...

I'm nor sure how much power I want to be sucked from the mains... Hopefully I can run it on 120/60hz but that may pull to many amps, 220 may be its future.

any other info just ask...

Wouldnt 220v pull more amps than 120?

Matt

I do think no so much. Lets say it pulls 1000w from any source, 1000w, at 120 thats 8.33 amps yes?
now on 220 thats 4.54 amps correct? same wattage different current eh!

And about the static spark gap, What would I use to blow the gap clean? like a PC fan or somwething?

GimpyJoe

Tue Mar 14 2006, 10:03PM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

A shop vac is the best option for quenching with MOTs. Also, check out Greg Hunter's "inside-out" sucker gap on

(go to Greg's site). It's easy to make, super cheap, and has pretty good quenching and cooling.

HV Enthusiast

Wed Mar 15 2006, 01:46AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

you won't be able to quench a static gap for a MOT based coil - low voltage / high current.

Try the sucker gap.

Sam

Wed Mar 15 2006, 02:36AM

Registered Member #227 Joined: Mon Feb 20 2006, 10:47PM
Location: Cambridge Ontario, Canada!!
Posts: 127

Hey guys! I got to thinking and I just can leave something alone... I smoked a ballast,(look closely at the last picture) almost ruined my ac power supply and I burnt my finger.... But I got a Tesla up tonight. The Tank cap(8.11nF saltwater) was a quicky and same for the rest. Well check it out! the spark gap being of most interest was working with some minimal cooling but it gets really hot! the one electrode anyway. The Run was week at about 750w and a lot off loss because I need a bigger tank cap (160nF-ish). What do You guys think now?

GimpyJoe

Wed Mar 15 2006, 03:38AM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

You'd be better off with rounded gap electrodes instead of pointed ones. And also try a flat spiral primary.
With such a small capacitor and pointed gap electrodes, your gap is probably just arcing and not quenching at all.

It looks good so far, though. The only thing that worries me is the burned-out ballast. I have no idea whats going on with that...

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