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Old 2nd Jan 2018, 6:25 pm   #1
Al (astral highway)
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Default Letting you down gently...

Hello everyone,

The New Year can be an opportunity to step back and see things clearly. This has certainly been my experience so far.

I'm posting this to let you know that even having come this far in terms of investment in time and materials acquisition, I will not, finally, be takin the next iteration of this project any further.

Six weeks or so before Christmas, I had ordered a bespoke EHT transformer from Ed, and at the time, I was hoping to rebuild the power supply from scratch from now on.

It arrived, and has sat in its original neat wooden packing case every since. It was supposed to be the core component in the highest-powered valve Tesla coil that I'd ever built, having exhausted the potential of models relying on paralleled microwave oven transformers (which I no longer advise).

Here's what's happening:

1) I have been in hospital for most of December as announced elsewhere. I am still in the system and have a lot of work to do to get to a place where I can be my best self, bearing in mind all the challenges going on, and those yet to come.

2) It is simply not realistic for me to be hefting around components that weigh up 10, 20 or 30Kg each. This used to be trivial for me, but my physical recovery has limits lower than what I expected. I would be paying a high price if I tried to keep moving around a growing 'boat anchor' of a thing, whose final weight is likely to be 60-70Kg!!!


3) I had already begun working on a lighter model that could still yield good results, but using only digital electronics and contemporary high-power switching devices.

4) Hence I will continue with the new design, aiming for a total weight under 5Kg. I expect to produce decent arcs, however using an entirely different topology to the design described in this long thread.

I retain the secondary coil, because it embodies hours of work.

I've added 12 coats of marine spar varnish to the three or four that Richard finished it with after lathe-winding it, as well as three to 8 turns of Kapton tape on top (for resilience against dropping, scratching and flashovers, according to where the highest stress is) and added a copper disc on top and an RF ground point at the bottom.

-----------------
You might ask, how do I feel after reaching this decision? Well, at the moment, I just feel relief: the kind of relief that arises when we take stock of a challenging or energy-sapping situation and make a decision that is the best for our wellbeing.

I do also feel a tiny sense of frustration about the 'why' behind the reason, but it is an essential part of my rehab to accept what can't be changed, rather than going on as I can use willpower to overcome any obstacle. Some I can, some I can't!

Where does this leave us?

Well, several things arise for me.

1) I am very happy to help anyone else who feels like starting on a valve-powered Tesla-coil journey. However, it is quite an adventure and best to start small, I should say! I wouldn't advise going above 150W RF for a first power-oscillator design unless you have done EHT and RF power work before. Mechanically-excited coils are a much kinder introduction.

2)I will be disposing of, by sale, various items that were lined up for the next build.

These include the big oscillator valve, its ceramic socket (wired with common mode choke, decoupling, ect) the brand new 1.8kW EHT transformer, and 5 * gigantic 4uF 2500V rated capacitors, oil filled. This is just a teaser to gauge interest and at an appropriate time I will make a new 'parts offered' thread, which will very much require FDS involvement!

3) As far as the new circuit goes, I already have my new notebook going and have been sketching the physical build, doing a load of maths, and choosing, designing or refining control, shutdown, driver and power electronics circuit.

Despite unwanted limitations to my normally wonderful ability to concentrate (which I hope will be resolved with external help) I've been doing this prep in a dedicated new notebook.

4) on this particular leg of my journey, I've deepened my understanding of;

Magnetics (RF), amorphous alloy toroids, 'catastrophic failure' of multiple components and causes, EHT power supply design and decoupling, low-mu HF power oscillator design, coupling and overcoupling, transmission line behaviour, diagnostic and testing equipment, including some neat home-build pieces that I will continue to use... as well as a deeper understanding of how to measure what's going on. I built a lovely 75KV probe along the way, following a design by Hugo (Argus25). Even building that was quite illuminating.

Please note: I will start a new thread for the solid state version when I have reached at least 'First Light', if not beyond. As it's an entirely different topology and technology, it doesn't make sense to add it to this thread.

However, at that time, I wonder if the mods would accept that it's ok to post a one-liner here pointing to the solid-state version? (Hence leaving it open for a month or so?)

I know I'll be in touch with many of you on the forum, as usual, but particular thanks to all of you who expressed interest, excitement or general encouragement for this plan -- one that has an outstanding capacity to go wonderfully out of scope before you can blink!
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Old 2nd Jan 2018, 7:07 pm   #2
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Default Re: Letting you down gently...

Quote:
I had already begun working on a lighter model
Quote:
I will continue with the new design, aiming for a total weight under 5Kg
Phew!, I thought you had stopped doing it at first glance. A hobby is about having fun, by the look of it you have chosen such.
Quote:
I already have my new notebook
So it is not only me that keeps an A4 "Black and Red" on the kitchen table.
 
Old 2nd Jan 2018, 7:11 pm   #3
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Default Re: Letting you down gently...

As the gamblers say, when the fun stops, stop. I think you've made a wise decision.
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Old 2nd Jan 2018, 7:20 pm   #4
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Default Re: Letting you down gently...

"A man's reach should exceed his grasp", though that does sometimes lead to disappointment. No red and black A4's here, much prefer A5 with a spiral back; you can balance it on one knee, with the Avo8 balanced on the other .

B
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Old 2nd Jan 2018, 8:18 pm   #5
Al (astral highway)
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Default Re: Letting you down gently...

Quote:
Originally Posted by merlinmaxwell View Post
Phew!, I thought you had stopped doing it at first glance.

No way! Far too deeply engrained in my psyche now! It's just a relief to 'let go' of the impossible, and make way for the possible! It's great having you as one of my key project-champions!

Quote:
Originally Posted by merlinmaxwell View Post
So it is not only me that keeps an A4 "Black and Red" on the kitchen table.
Ahah, yes, actually, a.t.m at least, I carry it around with me nearly all the time!
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Old 2nd Jan 2018, 9:07 pm   #6
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Default Re: Letting you down gently...

Even with a small Tesla coil about the place, the neighbours will still swear you've been nicking parts from the local cemetery.

But modern electricity supplies save all that uncertain mucking about with kites, and switch-mode technology allows creation in a much smaller 'labratory' as the best movies call it. You need to get yourself a good Igor.

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Old 2nd Jan 2018, 10:05 pm   #7
Al (astral highway)
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Default Re: Letting you down gently...

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Originally Posted by Radio Wrangler View Post
... switch-mode technology allows creation in a much smaller 'labratory' as the best movies call it. You need to get yourself a good Igor.
Hi David,

I love your sense of humour, dry and always on the money! And you're also one of the project champions (consciously or not!), as well as combining brilliant insights on the technical side, here and all around the forum. However geeky things get, you keep both feet firmly on the ground.

Thank you David!
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Old 2nd Jan 2018, 11:25 pm   #8
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Default Re: Letting you down gently...

I'm not that smart. I still haven't got a solution to the problem of a crowd of peasants with torches.

And I've got to live with this sense of humour almost 24/7

David
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Old 3rd Jan 2018, 12:13 am   #9
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Default Re: Letting you down gently...

I *love* this Forum
Al, all I can suggest is: adapt; survive - and above all, keep on having fun.
Sincerely,
Guy
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Old 3rd Jan 2018, 8:21 am   #10
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Default Re: Letting you down gently...

Be like a reed in the wind my friend and not like the mighty implacable snaggle toothed snark.

Onwards and upwards, or as was written on the destination board of Ken Kesey's bus.....further. Andy.
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Old 3rd Jan 2018, 11:48 pm   #11
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Default Re: Letting you down gently...

Totally with you on moving away from Microwave Oven Transformers for this sort of project.
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Old 5th Jan 2018, 6:51 am   #12
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Default Re: Letting you down gently...

Quote:
Originally Posted by astral highway View Post
It's just a relief to 'let go' of the impossible, and make way for the possible!
Al,

You have been through and are going through a lot and having to adjust your plans wisely.

You remind me of the brilliant scientist in Metropolis, who also liked to work with high voltages. (image attached)

Hope all is progressing well for you.

Hugo
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Old 5th Jan 2018, 8:18 am   #13
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Default Re: Letting you down gently...

ROTWANG!

AL, this will be a bend in the road on your journey, but it might also be a shortcut.

Tenacity and perseverance are two things you have in abundance!

We're all with you in this.
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Old 5th Jan 2018, 9:38 am   #14
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Default Re: Letting you down gently...

Back in the nineties when Electronics Weekly and Electronics Times were distributed for free in the electronics trade, one of them printed that Metropolis still as a caption competition.

The winning entry (far better than mine!) was "All new Ann Summers products undergo thorough EMC testing before CE marking"

David
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Old 7th Jan 2018, 10:51 am   #15
Al (astral highway)
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Default Re: Letting you down gently...

Thank you, everyone, I really appreciate your supportive commments; they mean a lot to me: thanks for believing in me - I’m writing this as an in-patient again, hence the through-the-night activity on this forum.

I’ve experienced quite a few ‘interesting’ experiences in my lifetime, including when someone dropped a front tractor tyre on me from a first floor window (don’t ask!). That probably explains a lot about my sometimes obsessive take on things. The tyre survived intact.

Ken, thank you, that’s very thoughtful. Erm, but what is ROTWANG?!

And I love humour in all its forms, so thanks for entertaining me too, Hugo and David!

I can’t wait to be able to start the mechanical and electronic build of the new project; no promises on completion date this time.

Hugo, I must dig out Metropolis! The still is familiar, but not the context!
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Old 7th Jan 2018, 11:32 am   #16
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Default Re: Letting you down gently...

For a little light reading while you're laid up, you might be interested to research the special effects in Metropolis - hugely complex for their time.
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Old 7th Jan 2018, 12:16 pm   #17
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Default Re: Letting you down gently...

A while back I saw Adam Lambert with Queen in concert. It looked to me that Brian May (who is big on Astrophysics) had probably been responsible himself for a lot of the video graphics. He also tried to explain to the crowd the Twin's Paradox. There were space scenes in the images. One or more of the video graphics were taken directly from Metropolis, with an image of Maria with a circular corona discharge travelling up and down around her body. Actually the whole lighting & video presentation was pretty good, as was the music. The images from Metropolis are quite remarkable for the time they were made and invoke a time when electricity was just starting to really capture the imagination of the public, but also science fiction writers and movie makers.
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Old 7th Jan 2018, 3:21 pm   #18
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Default Re: Letting you down gently...

Metropolis clips, including what I will now always think of as the "Ann Summers" robot, are used in the "Radio Ga Ga" video, official Queen version here:

https://www.youtube.com/watch?v=azdwsXLmrHE

Does anyone recognize the radio shown in the 1940's sequence?
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Old 7th Jan 2018, 4:57 pm   #19
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Default Re: Letting you down gently...

Al [p15*] well you said you've been feeling "tyred" lately but not like that
Simon Armitage used to read a great poem about finding a giant tractor tyre that he and his mates were rolling down the valley into his Huddersfield village [his dad re-cycled them for a living]. It got completely out of control hurtling into the distance . They [finally] went home in terror of reprisals but it was a baffling conclusion-no injury or damage and the tyre was never seen again [not even by his father].

Further to my flagging the Tesla program on Radio 4 yesterday and your [generous] comments about him [November 8th] on the "Coil" thread, it occurs to me that you may be one of the best qualified people to comment on his work that I have come across. Just thought I'd throw that one in
I think Paul Sherwood was right when he said you made the right decision. My experience with M E/CFC taught me that "ploughing on" instead of accepting limitations is not a good idea and can exacerbate things!

Dave
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Old 7th Jan 2018, 5:48 pm   #20
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Default Re: Letting you down gently...

Hi Al, I'm sorry but I assumed everybody knew that the scientist who transformed Maria into a robot is named Rotwang.

Looking back at my post it does look a bit sweary!
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