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What to do now... (partially completed Tesla coil)

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Sam

Tue Mar 20 2007, 04:17AM

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

will do, but these new caps work great, i got 8 going and the variac pulls like 3 less amps. cool!! bigger arcs and sparks.

My GF is really scared of it, she wont even go near it.

EDIT:

QUESTION??? I havn't yet fully calculated the voltage and current I am getting off the 2 MOTS. how would I go about doing this. I have a multi-meter but t only goes up to 750vAC.

I'm thinking like 9-12Kv?

sparky

Tue Mar 20 2007, 07:27AM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

sure... here is what I do. Run 120V into the secondaries of the MOTs. Measure the voltage off the primaries and you should get 3 VAC --- from 120V input on the secondaries. 120V divided by 3 V = 40 which is how many time the voltage will increase if you feed 120V reverse into the system. 120V x 40 = 4800 V .... tada!!

I can assure you that your voltage ratio will be 40:1 or 4800V at 120V input. With a voltage doubling circuit you will be running ~10 kVDC into the Tesla Coil. Current wise --- well I'd use a heavy duty current clamp meter and measure the input current first. But I'd be willing to wager that if you are using MO caps 0.9 -1.0 uF you'd probably be pulling 600mA + on a dead short. 3kVA total mains power draw... maybe a bit more.

I'd be really cautious with this circuit...

Sam

Tue Mar 20 2007, 07:11PM

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

well at 12vac, I get 164.5 vac per MOT.

so I figure 164.3V * 10(thus 120v input) I get 1.645Kv with 120vac input

does that work right?

EDIT: tried the above method. I get 4500V on the dot when calculated(both MOTs)

and when my variac is at its max (161.7V) I can get 6080V.

Question, when going through the doubler is it just simply *2 or can it be complex?

BTW here is hows its set up
TeslaMOTS

ERROR IN THE PIC, T1&T2(C) 12.16Kv(161.7) should be T1&T2(C) 6 Kv(161.7)

[Edit: 400 pixels maximum]

Marko

Tue Mar 20 2007, 11:11PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

What is your charging reactor? That transformer in behind?

Doubler will give you 2x peak voltage from the mot's. So if (for example) each mot gves 2000VAC your DC output will be 2*2*2000*1.414 ~ 11312V.

Sam

Wed Mar 21 2007, 12:03AM

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

its a 5 amp choke. thanks for the math.

The Choke

1142455903 227 FT4253 100 0650

Marko

Wed Mar 21 2007, 12:10AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

If I figured it all right out, you have NO charging choke?

Voltage doubler alone, as it is, will not work in a tesla coil because the spark gap will dump all the energy from your filter caps with each firing, in a massive power arcing wich would blow your diodes right up.

If you are about for DC resonant charging then you need very large output choke (tens of H) and de-Qing diode in series with output.

Steve conner has great coil and info about it:

You could probably use big resistor to ballast the output of your doubler, but it would just waste large amount of power and it would probably be worse than if you ran the coil from 2 undoubled mot's.

Sam

Wed Mar 21 2007, 12:15AM

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

http://hot-streamer.com/greg/motpic.htm

His works

"which ran at full throttle for months without popping any diodes"
http://hot-streamer.com/greg/frames.htm

sparky

Wed Mar 21 2007, 01:17AM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

Sure thing, Greg Hunter employed a straight DC rectified MOT PSU. Sure you'll get a fair output but you will loose power and performance without using chokes... I've tried both methods - with and without chokes, and the latter improves the Tesla coil performance considerably.

Sam

Wed Mar 21 2007, 02:54AM

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

ARG, Well Ill just focus on my RSG for now. Figure the rest out later.

sparky

Wed Mar 21 2007, 05:22AM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

Its not a big deal... if you have spare MOT units hanging around these can be hooked up to act as chokes. Just short the primaries and run the high voltage through the secondaries.

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