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Just bought this off eBay...

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LAN_403

ped

Mon Jul 24 2006, 06:54PM

Registered Member #305 Joined: Sat Mar 11 2006, 04:27PM
Location: Liverpool, UK
Posts: 29

so im gonna need some help from you experienced guys setting it up, mainly the capacitance to use and construction of the MMC , also ive never used a rotary spark gap before

the link >

cheers in advance for any help , ps is it a decent price?

Simon Barsinister

Mon Jul 24 2006, 11:17PM

Registered Member #116 Joined: Fri Feb 10 2006, 03:19AM
Location: Erie Pa, USA
Posts: 29

Why did he quit (or fail to start)......it was nearly done! Just wire it up n tune it. $100 to $200 would be about tops I'd pay.

Rich

ped

Wed Jul 26 2006, 09:39PM

Registered Member #305 Joined: Sat Mar 11 2006, 04:27PM
Location: Liverpool, UK
Posts: 29

i know, but his loss is my gain!

if you look at the NST it says 3kv -E-3Kv does that mean its like normal transformers IE 6kv between the outputs and 3kv each with reference to ground?

robert

Wed Jul 26 2006, 10:15PM

Registered Member #188 Joined: Thu Feb 16 2006, 05:18PM
Location:
Posts: 67

Yep thats right.
Almost any high voltage transformer has the center of the secondary grounded (because this makes it possible tu use half of the isolation material).
Therefore none of the output connections may be connected to ground or to anything that is grounded by itself.
This is no problem for our use since the primary circiut doesnt need to be grounded on any point.

BTW:With rotary sparkgaps, never forget a safety sparkgap that fires just a little above the unloaded transformer output voltage.
Without this there is a very real chance of destroying the transformer and other parts if the motor fails or the gap fails to work properly.

colin heath

Thu Jul 27 2006, 06:28PM

Registered Member #123 Joined: Fri Feb 10 2006, 12:58PM
Location:
Posts: 162

WOW! That's the rotary gap i built years ago

. Hope it all still works as well as it used to. I have attached a pic of the gap in action on my coil

Be careful using that gap on an NST. It's an asyncronous gap and NST's don't like them.

Cheers

Colin

colin heath

Thu Jul 27 2006, 06:30PM

Registered Member #123 Joined: Fri Feb 10 2006, 12:58PM
Location:
Posts: 162

heres another

ped

Thu Jul 27 2006, 08:24PM

Registered Member #305 Joined: Sat Mar 11 2006, 04:27PM
Location: Liverpool, UK
Posts: 29

gettaway! u mean u actually built that? superb , small world eh , well its going to a good home, could you elaborate on the NST vs spark gap problem? also, why the extra toroid on the top of your coil?

ped

Sat Jul 29 2006, 02:41PM

Registered Member #305 Joined: Sat Mar 11 2006, 04:27PM
Location: Liverpool, UK
Posts: 29

well i got the bits today, and it says "RSG by C Heath" !!

amazing...small world eh

colin heath

Mon Jul 31 2006, 03:40PM

Registered Member #123 Joined: Fri Feb 10 2006, 12:58PM
Location:
Posts: 162

Hi Ped,
There are others on here much more qualified than me to expand on the asrsg problem. I just know not to use them. The extra Toroid is to add top capacitance to help performance and lower resonant frequency. The two stacked gives you good shielding of the secondary also.
I remember that shameless self promotion exercise with the brass plate now

Well have fun with that gear.
Seems that is Nick Fields old coil he used to write the inductance on them so have alook.

Cheers

Colin (gap builder) Heath

Hazmatt_(The Underdog)

Mon Jul 31 2006, 10:15PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

asrg's are a lot of trouble to synchronize them to your particular charging needs. Using a variac alone is not good enough. Not to mention you really don't know what your B.P.S. is without some kind of strobatic. It is preferred to use a synchronous type spark gap because the synchronous will give you the rated speed and better then 1% deviation from that speed. You will usually hear a slow modulation in the speed of the motor as it operates. The speed varies at about 2Hz if I'm not mistaken, but it is noticable. You will also notice that in the overall performance of the coil. The output spark length will grow and diminish somewhat as the motor phases in and out. But overall, the synchronous is much less troublesome. Make sure if you do use an asynchronous, to have a good static gapping system in parallel. This is important because of mis-synch and misfires. It will protect your transformer to an extent. Also make sure you have a good HV side line filter to protect from spiking.

I have run simulations and found that without a simple RC filter, I have spikes on the order of 2MW! and they go right back to the terminals of the transformer. With the RC filter I can cut the spikes down anywhere from 4A right down to the normal operating current of 120mA. It really does offer wonderful protection. Resistors will Not do the job on their own, do not make that mistake. It is the capacitors that are doing all the work, so have some nice small doorknobs on each line to centertapped ground to protect your spiking.

Good luck and happy TC'ing

Matt

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