15th Nov 2017, 9:30 pm | #121 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,194
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
Hi Al, have a look at CVT's, capacitor voltage transformers
Used on power grids to read the line voltage at much lower cost than a wound one for 400Kv. Basically 2 HV caps and a transformer from the junction. It works on AC and can be pretty accurate (used for bulk metering) if the frequency is stable. Ed |
15th Nov 2017, 9:43 pm | #122 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,608
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
You got it! I applied a thin coat of varnish to stabilise the winding, then, after 24hours to let that dry, several thick coats, letting it dry for a day each time. After each coat I switched on the lathe, turning at about 15rpm for about 4 hours per coat to stop the varnish running. It worked much better than I hoped it would.
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15th Nov 2017, 9:43 pm | #123 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
Hey Ed, will do, thank you. Are you thinking for me to apply this to measurements around my circuit? I'm building an EHT probe , but it's for RF signals, so it would still be useful for me to also be able to measure the pulsed DC in the power supply. Is that a suitable application for CVT's?
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Al |
19th Nov 2017, 11:24 am | #124 | |
Dekatron
Join Date: Nov 2006
Location: London, UK.
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
Quote:
What’s your preferred varnish? Thanks again for your diligent and incredible work!
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Al |
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20th Nov 2017, 7:44 am | #125 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
I use whatever varnish i have lying around though the outside stuff seems to have a better finish.
Good to see your making progress Al. Andy.
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3rd Jan 2018, 2:50 pm | #126 |
Hexode
Join Date: Jul 2016
Location: Ashby de la Zouch, Leicestershire, UK.
Posts: 253
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
After all that work, the bottom line is, how long a spark will it generate?
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"One small step for man".....because he has arthritis. www.retinascope.co.uk Albert. |
3rd Jan 2018, 9:07 pm | #127 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Design-and-building a large valve Tesla coil (class C, Armstrong oscillator).
View master, that’s the thing! We’ll never know. There is an approximate formula for valve Tesla coils, based on power in. According to that , we’d expect 70 cm plasma from the anti node, but the circuit was never realised with its new transformer. So it’s a moot point.
Somebody may care to take on the challenge: I will offer all the parts except the secondary coil for sale here before moving on to a EBay to recoup some of my spend.
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Al |