EHT power supply design and construction

ian field

Joined Oct 27, 2012
6,539
Aye! Bewared, however, that said method not uncommonly leads to 'hot-spots' (with subsequent breakage or permanent shift of magnetic properties) and, in my experience, destructive arcing!:eek::eek::eek:

Inductive heating (via a loaded driver) -- or the solvent/heatgun technique described in the tutorial require more patience - howbeit said 'virtue' is, in this case, amply rewarded!:cool::cool::cool:

Best regards
HP:)
Breakage is a possibility with almost any method of parting glued ferrites.

Neosid (where I once worked) the development technicians sometimes fired prototype ferrites in the microwave when it wasn't possible to disrupt the production conveyor through the kiln.

When ferrites get unintentionally magnetised, a microwave is a convenient way to raise them above their Curie point.
 
When ferrites get unintentionally magnetised, a microwave is a convenient way to raise them above their Curie point.
Yebut -- Isn't that "throwing the baby out with the bathwater"? -- To wit: In my experience, temperatures exceeding the Curie point tend to permanently alter the magnetic properties:eek:...

As always, maintaining an open mind
HP:)
 

ian field

Joined Oct 27, 2012
6,539
Yebut -- Isn't that "throwing the baby out with the bathwater"? -- To wit: In my experience, temperatures exceeding the Curie point tend to permanently alter the magnetic properties:eek:...

As always, maintaining an open mind
HP:)
Ferrites are a sintered ceramic base with various oxides of iron mixed in.

The powder is fed by a hopper into a press that forms it into the required shape, then the operator stacks them on sintered alumina palettes.

They then get loaded on the conveyor that takes them through the firing kiln.

I've no idea what temperature the sintered ferro-ceramics are fired at - but they pump an artificial nitrogen atmosphere into the kiln to exclude oxygen and prevent it altering the iron oxide content.

Its dull red heat at least - maybe proper bright red.

Remembering that one of the development techs told me they sometimes fire prototypes in the microwave, reminded me that spark plug insulators are lossy enough to glow red in a microwave - and that ceramic doesn't contain much iron.
 
Ferrites are a sintered ceramic base with various oxides of iron mixed in.

The powder is fed by a hopper into a press that forms it into the required shape, then the operator stacks them on sintered alumina palettes.

They then get loaded on the conveyor that takes them through the firing kiln.

I've no idea what temperature the sintered ferro-ceramics are fired at - but they pump an artificial nitrogen atmosphere into the kiln to exclude oxygen and prevent it altering the iron oxide content.

Its dull red heat at least - maybe proper bright red.

Remembering that one of the development techs told me they sometimes fire prototypes in the microwave, reminded me that spark plug insulators are lossy enough to glow red in a microwave - and that ceramic doesn't contain much iron.
Thank you for the informative post!:):):) --- So it seems permanent changes to the magnetic properties of overheated ferrite and Fe powder cores owes to reactions with atmospheric O2 and/or core material density changes?

Ferrites are a sintered ceramic base
--Emphasis added--

Ah ha! -- That would explain their ridiculous brittleness/pathetic tensile strength! -- Now I get it!:cool:

Very best regards
HP:)
 
LOPT Disassembly ('prequel') installment moved to 'end' of thread for convenience -- to be 'subsumed' by tutorial upon completion...
Last action Mar 2 2016

Step 1) Identify construction style of LOPT to be optimized.


Task
1)
Identify construction style via the description most closely matching the reader's device in the following...

Full EMF AC LOPTs feature one of two general construction styles as outlined below:

Style 1)
Features a single piece frame ('clamp') -- the rails of which maintain compression on the core via a single linear ligature fashioned of a metallic strap or bolt extending from rail to rail across the top of the upper form leg 'facet'.

Example of style 1
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_desc-jpg.101778/

Style 2)
Features two independent metallic frame pieces OR a metallic half-frame and a backing plate/PCB -- such assemblies are bound by a single "U- bolt"/"U-strap" or two linear bolts/straps extending along the outer aspects of each horizontal form leg...

Examples of style 2

View of LOPT from 'closed' side of "U bolt" ligature

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt1a-jpg.101781/


View of LOPT from 'open' side of "U bolt" Ligature

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt1c-jpg.101784/


View of LOPT from 'closed' side of "U strap" Ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt2a-jpg.101785/

View of LOPT from 'open' side of "U strap" Ligature
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/ubolt2b-jpg.101786/

Step 2) Removal of form frame ('clamp')

Tasks:
1)
Remove any tape, looped conductors, ground leads, etc. ensnaring/bonding the frame to the form/core.

2)
Free each end of the frame ligature{s}

3A)
In the case of cylindrical bolt{s} or a cylindrical shaft 'U Bolt':
Remove backing fasteners (i.e. nut{s}/burs{s},etc...) then carefully withdraw the bolt{s} from the assembly.

3B) In the case of independent strap{s}, or a 'U Strap':
Straighten and/or unsolder each fastening 'tab' then splay the frame rails such that the ligature 'ears' clear the ligature 'tabs' --Or-- if so constructed, remove the backing plate/PCB from the ligature ends ('tabs').

4) Remove the transformer (i.e. core and winding assembly) from the framing/clamping/mounting components -- please retain the frame and all associated hardware!

Image of transformer following removal from a single strap-ligature frame:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptdesc2-jpg.101780/


Annotation of assembly features referenced in following steps:

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/annotated-jpg.101788/


Step 3) Procedure for removal of strap ligature{s} from LOPT core/winding assembly:

1)
Meticulously straighten and deburr the exposed segments of the frame ligature{s}.

2) Carefully 'work' the frame ligature{s} free of the adhesive, then withdraw it/them from the space intervening the form and winding assembly{s} (and, hence, off of the form) -- Under no circumstances apply counter-thrust or torque to the EHT winding!

Ligature partially withdrawn from assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptligwdr-jpg.101790/

Ligature (in foreground) fully withdrawn from assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptligout-jpg.101789/

Note: Inasmuch as same will be removed and discarded in later steps, damage to the external auxiliary windings (i.e. those on the form leg opposite the EHT winding) or coaxial auxiliary windings immediately adjacent to the core/form leg is of no consequence -- Care must be exercised, however, to avoid damage to the brittle ferrite form/core via excessive force or mechanical shock... Also - avoid handling the assembly by the EHT winding!

Step 4) Removal of external auxiliary windings from 'lower leg':

Tasks:
1)
Using a utility knife or similar tool, linearly section the full length of the 'external' Aux winding assembly. --- Note, the winding in reference resides on the form leg opposite that carrying the EHT winding!!!

2) Peel, crumble and/or break the 'external' Aux windings away from lower form leg.

Step 5) Separation of form pieces

Caution: In performance of the following tasks, it is of paramount importance that no torques or linear forces are applied to the EHT tyre! -- Moderate forces may be applied to the auxiliary shell and moderate compressive forces may be applied to the ferrite form longitudinal to the EHT winding 'leg' only!

3) Endeavor to remove (or loosen) any shims intervening the form and central aspect of the auxiliary sleeve -- While damage to the auxiliary sleeve or winding is of no consequence, care must, nonetheless, be exercised to avoid breakage of the form!

Image of wooden shims (indicated by pick)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptshim-jpg.101791/

4)
Using a #3 sharp, uterine (preferably fenestrated) curette, or similar non-ferromagnetic stainless steel instrument, carefully 'clean' the lower form leg of superfluous epoxy -- Note: Use of razor blades or other ferromagnetic or 'soft' metallic instruments will likely 'foul' the ferrite via metallic transfer to same!

5)
Submerge the lower leg of the form (prepared as per task #4 above) in acetone for a period of ≈ 90 minutes at 16°C ↔ 33°C -- Note: the EHT winding assembly must not be submerged, splashed or otherwise wetted with acetone! -- nor should acetone be allowed to condense on same! Owing to the flammability of ketones, said procedure is best preformed in open air or in an open container under a fume hood -- a closed container is not recommended owing to liability to condensation...

6) Immediately following removal from the acetone bath, drive the reluctance spacer out of the lower form joint using an appropriate feeler gauge leaf --- Note that during and following removal of the reluctance spacer/adhesive from the 'lower' joint, application of even moderate distensive or constrictive forces to the form will result in significant cantilevered forces at the 'upper' form joint with (almost certain) breakage of one or both form pieces!

Of special concern in this regard:
A)
Do not attempt to expand the gap while removing the spacer! -- The leaf thickness must be less than the gap width! Maintenance of an absolutely parallel relationship between leaf and form piece ends (i.e. gap 'walls') is imperative!

B) Following removal of the spacer, take care to avoid application of transverse pressure or piece-to-piece torsion to the form! -- The safest handling method is manipulation of the assembly from one 'side' (i.e. by one form piece) only!

7) Following clearance of the lower form joint of its reluctance spacer and adhesive, continued half-to-half form tenure owes to the upper form joint adhesive (at the center of the EHT winding assembly) - and, to lesser extent, adhesion of each form piece to the form sleeve of said assembly.



....WORK IN PROGRESS.....

Last action Mar 2 2016
 
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@Aleph(0)

Ok here's the progress on the 'prequel' (now post #366)

1) Images added to facilitate comprehension of tasks in regard to seperation of the form (core) pieces.
2) Reordered tasks such that the form will not be in its highly vulnerable (cantilevered) 'state' during manipulation/pressure 'intensive' ligature/shim removal tasks...
3) Rewording and many error corrections....

Proofreading assistance would be greatly appreciated!:cool:

Best regards
HP
 
@Aleph(0) et al.

It seems the site software has been changed such that image files are now resized during upload so as to limit them to a few hundred kilobytes -- A very good thing -- inasmuch the former difficulties with reliable image display seems to have been related to their (excessive) size (≈2.5 MB) --- Unfortunately, the new 'auto-sizing' feature operates only during upload - hence my requirement of re-upping all the images, re-addressing all links to same and deleting the old (over-sized) images from AAC's servers...

The very good news is that seven hours (and as many litres of java) later it's a fait accomplis!:cool::cool::cool: --- We may now look forward to images that reliably display - hence my plan to re-embed same upon completion of the tutorial!:)

Many sincere thanks to those responsible for implementation of the image auto-sizing feature!:):):)

Best regards
HP
 
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Thread Starter

Aleph(0)

Joined Mar 14, 2015
597
HP I think your work paid off cuz I just tried to load a pic and is instant even with my sucky vpn:D! HP you have done a lot of work and I am very happy:)! HP JC wants to know for sure it's ok if he posts on here so I said I'll ask again but I told him if you say something he can believe it first time! I also told him that it's kinda lame for him to think of you as his _soulmate_ if he doesn't even know you well enough to be sure of your meaning:rolleyes: HP I made post on your thread about hv rectifier sry cuz it's a little OT but I say important point! cu soon:D!
 
HP I think your work paid off
HP you have done a lot of work and I am very happy
Pleased to hear it! -- I'm yet struggling with the 'after effects'!:eek::eek::eek::)

HP JC wants to know for sure it's ok if he posts on here so I said I'll ask again but I told him if you say something he can believe it first time!
@Aleph(0) -- You seem to be missing a crucial point --- As per site policy, as TS/OP this is your thread! Hence the matter is technically out of my hands!:cool: --- FWIW, My opinion is that this is a public discussion (as opposed to a private conversation) hence (again, IMO) any and all well-intended participation is both welcome and strongly encouraged!:)

I also told him that it's kinda lame for him to think of you as his _soulmate_ if he doesn't even know you well enough to be sure of your meaning:rolleyes:
---Emphasis added---
That is certainly the single most emetic word in the English lexicon!:rolleyes::rolleyes::rolleyes::rolleyes::rolleyes::rolleyes::rolleyes:

That makes four of 'them' this year and it's only March!:eek: Why?!?!?!?:(:rolleyes: (Can it be that Kissinger's FAMOUS QUOTE in regards to 'power' likewise applies to EHT?;)) --- I'll wager that bona fide instructors know how to deal with this 'sort of thing'!? -- Though I would have thought 'twenty-somethings' would adapt a more serious attitude...

Again, as far as I'm concerned, he's welcome here so long as he eschews sentimental, amative or otherwise personal overtures --- 'Students', colleagues, (civil) critics and the idle curious are welcome! -- 'Groupies', however, need not apply! (You getting this, JC?:rolleyes:)

Good deal:):):):)

All the best!
HP:cool:

PS:
ATTN: @Aleph(0) or 'JC' --- If he will be participating on this thread, please advise me of JC's user name -- You may transmit same via PM or Email message if you don't wish to post it here...:)
 
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JC? I thought any religious context was to be eschewed?
No worries! -- I assure you that "The Man of Galilee" is quite another 'JC' on sooooo many levels!!!;););):D

Seriously, the 'JC' to which Aleph and I refer could be an asset to this thread (and, indeed, these fora in general) was he to 'cast aside' his penchant for 'chasing rainbows' and otherwise larking about -- But then, sadly, it seems dearth of focus is the bane of contemporary vicenarians (and, so it seems, more than a few nascent tricenarians:rolleyes:)

With (foolish?) optimism
HP:)
 

Thread Starter

Aleph(0)

Joined Mar 14, 2015
597
I'm yet struggling with the 'after effects'!:eek::eek::eek::)
HP Do you mean like ophthalmic migraines cuz of too much caffeine? I know cuz it can do that to me too:eek:!

HP JC says on his word that he'll steer clear of personal feelings so I say you can give him a chance to post on here?

As per site policy, as TS/OP this is your thread! Hence the matter is technically out of my hands!:cool:
HP That's nice try to cop out but I don't see it that way cuz you add most of content so it's your thread! I can say so cuz I'm sovereign here so I abdicate and cede thread to you:p!

Why he 'cries' on your shoulder
I say it's like cuz I have _HP genes_ I'm totally superhuman in his eyeso_O

That makes four of 'them' this year and it's only March!:eek: Why?!?!?!?
If you can't even understand that how can I explain:rolleyes:?

HP I told him it's good thing for him that you're not in same league cuz if you returned affections it could lead to embarrassing case of frostbite:eek::p

Now this is on topic!:) HP I can write installment to explain obscure tools and to suggest alternatives. Does that work?

HP I was thinking more about diodes connected in series so plz answer question I'm posting on hv diode thread:)
 

#12

Joined Nov 30, 2010
18,210
HP I can write installment to explain obscure tools and to suggest alternatives. Does that work?
It works for me. I suppose it would be called an Appendix: alternate tool options

ps, It is unlikely that you can forfeit your ownership of the Thread. Forum Rules. That would require a Moderator to make a special dispensation.
"Moderator forgive me for I have sinned.":D
HP is free to copy the information into her blog after it is properly polished.
That's what I would do.;)
 

Thread Starter

Aleph(0)

Joined Mar 14, 2015
597
Thanks #12! I will be very happy to contribute to project now that I have more free time! I'm just teasing HP about thread ownership and all that cuz she likes to bring that up as a cop out about which posters to encourage:rolleyes: Its all friendlier than it sounds:)!
 

Thread Starter

Aleph(0)

Joined Mar 14, 2015
597
I hope so!
Having been frightened by a female person when I was of tender age, I worry that a cat fight will break out at any moment.:eek:
Ha ha! HP and I are family so when we're being catty we're totally domesticated kitties:D!

ps, The "tender age" was about 20 years ago.:D
The only scary women of mid 1990s I've heard about are politicians but they're totally too scary to think on and off limits cuz of non politics rule:cool:

Now you are reminding me of old joke about verbs vs adjectives:
So person a says "I don't believe in frightening women!"
Then person b responds "Then you haven't met my mother-in-law!":D
 
HP Do you mean like ophthalmic migraines
As well...:eek:
HP JC says on his word that he'll steer clear of personal feelings so I say you can give him a chance to post on here?
Aleph!? How how else can I say it? --- Yes! -- He's more than welcome here so long as he 'behaves' himself!!! -- Got it???:)

HP That's nice try to cop out but I don't see it that way cuz you add most of content
---Emphasis added---
And, um... Whose fault is that?:rolleyes:

I say it's like cuz I have _HP genes_ I'm totally superhuman in his eyeso_O
Hey, 'JC'? Assuming you're reading this, please consider my suggestion that you adopt of a more reticent attitude? -- You're going to find all of this rather embarrassing once 'the fever' has passed:rolleyes: -- Ya see, I was once 'youngish' myself - but without the specter of my ardent silliness remaining in public view for perpetuity:(:eek: Moreover, at 25 YOA, perhaps it's time you grew-up?!:cool:

If you can't even understand that how can I explain:rolleyes:?
Translation: "It's a generational thing that an old-party of 40 just wouldn't understand"???:rolleyes: -- Hey, Aleph? Now who's copping-out???;):rolleyes:

HP I told him it's good thing for him that you're not in same league cuz if you returned affections it could lead to embarrassing case of frostbite:eek::p
First off, as well you know, the concept of 'league' in social contexts is a collectivist contortion of freedom of association foisted upon the 'masses' with the aim of dismissing individualists as elitists/base materialists --- and, as such, an artificial construct at best (To wit: one's 'league' is as per the agenda of the 'beholder'/proselytizer) --- @Aleph(0) I know that we are in accord as regards the abject foulness that is collectivism in all its forms! -- So... Let's eschew said philosophy's 'buzzwords'!...K? [/sociopolitical rant]

Thus it is not that "I am out of JC's league" but, rather, that --apart from any/everything else-- I am well-neigh one generation his senior and with the disparity of cognitive, emotional and social development said 'distance' entails... That I need explain this says something about the present course of society -- something, I might add, rather less than auspicious!:(:(:rolleyes:

cuz if you returned affections it could lead to embarrassing case of frostbite:eek::p
You're funny, Aleph!!!:D:D:D -- Howbeit I suspect there are those who feel you're pressing a bit too firmly upon the bounds of good taste -- I remind you that this is a "family friendly" site --- as opposed to the Improv! (More's the pity!);):)

Now this is on topic!:)
Will wonders never cease!;):):):)

HP I can write installment to explain obscure tools and to suggest alternatives. Does that work?
Sounds like a plan!:) --- While I don't feel I've referenced any 'exotic' instruments -- I daresay description and, especially, suggested alternatives, are a good idea! -- please compose the installment then we'll collaborate on its 'integration' with the tutorial:):):)

All the best
HP:)











 
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