ATTN: @Aleph(0) --- Please see your (AAC) PM ASAP!...

To anyone who cares -- I will be 'back to stay' Saturday week (Aug 6) -- Again, many thanks for your patience!

Best regards
HP

 

@Aleph(0) -- Inasmuch as "I've 'promises to keep and miles (leagues?) to go before I sleep", etc.. -- I'm 'out of here' until next weekend -- Please do what proofreading you can and publish your suggestions on this thread no later than Friday - I plan to complete the tutorial (incl incorporation of your suggestions) during the week of the 7'th For the record, based upon several (telephone) conversations with him, IMO JC is not 'being a big baby' -- but, rather, a swamped student with an on-line gaming habit! -- So, Aleph, I'm placing you in loco parentis, as it were

All the best
HP

PS -- With profound apologies to Robert Frost

 

For the record, based upon several (telephone) conversations with him, IMO JC is not 'being a big baby' -- but, rather, a swamped student with an on-line gaming habit!

HP that's just BOGUS! When I'm f'ing around you call it _larking about_ but with JC you say he's victim of addiction to games HP I'm calling REVERSE nepotism!

Please do what proofreading you can and publish your suggestions on this thread no later than Friday

HP I will have proofreading done by Friday but I say we have to set hard deadline cuz it will never be perfect which means it will never be ready if we insist on perfection

 

HP that's just BOGUS! When I'm f'ing around you call it _larking about_ but with JC you say he's victim of addiction to games HP I'm calling REVERSE nepotism!

You're right, Aleph but you shouldn't be angry with Hp! It's only natural for ppl to expect perfection from their kids

@Jazz2C I say stop being a baby and just post your suggestions! Review is exactly what HP wants so she won't be angry cuz of corrections! Anyhow addendum was my idea so I fall on sword in your place if it doesn't fly

It's not that! It's just that who am I to correct or second guess Hp in any way? It's just something you can't understand without being in my shoes

 

It's just that who am I to correct or second guess Hp in any way?

So you _love_ HP too much to help her out? Words fail!

It's just something you can't understand without being in my shoes

JC then I don't want to understand! Death before Walmart in-house brand footwear!

 

So you _love_ HP too much to help her out? Words fail!

Plz don't trivialize what you don't understand

Death before Walmart in-house brand footwear!

OMG! I'd rather fall into the midst of a great white feeding frenzy than be seen at Walmart! If that's a bit much I can definately tell you I'd sooner go barefoot in January!

By the by if anyone likes Walmart I'm sorry if I offended you! But you don't have to worry! The 1'st amendment is on the run so I guess they'll be shutting me up soon enough

 

Plz don't trivialize what you don't understand

JC I say martyrdom doesn't become you! Is like HP said you need to have more discipline over your emotions cuz you'll be embarrassed when you get over it!

The 1'st amendment is on the run so I guess they'll be shutting me up soon enough

JC I understand what you mean but cuz some ppl who don't know you might take that the wrong way I'm taking liberty of clarifying:
What JC says about suppression of free speech is indictment of US Govt *NOT* AAC rules!
Only time I know of AAC being accused of censorship was by some loose cannon who had knee jerk reaction to Arduino article but she got over it

By the by if anyone likes Walmart I'm sorry if I offended you!

It takes all kinds to make a world but yikes! Talk about getting what you pay for! Being fair about it at least _Wallyworld_ is bricks and mortar! I say Amazon is the absolute bottom of the retailer barrel!

 

LOPT preparation tutorial development
Last action @ 08:37 UTC Jun 26 2016 -- Moved to end of thread @ 7/24/2016

Proofing pass 1

Scope of series:

Central topics:
This tutorial is one in a (prospective) series with focus upon low ripple, relatively high current/power PSU solutions for radiography and other modest photon energy ({1}≤ 2 MeV) particle accelerator applications - and, to a lesser extent, exploration of certain 'current intensive' electrostatic phenomena (e.g. electret photography, electret formation, electrokinesis, establishment of electrostatically 'cordoned' (atmospheric) pressure gradients, high volume ion-flow systems, etc...

Peripheral and extraneous topics:
While everyone is welcome to view and post questions (within the confines of this site's TOS/UA) - Please be advised that those having interests confined to the following topics/applications will not likely find this series particularly useful (owing to the availability of significantly less 'labor-intensive' solutions to same):

--'Pedestrian' and 'Quasi'/'Peri'-EHT applications:
(e.g. CRTs, PMTs/Image tubes, Gas discharge devices, LASERs, 'negative ion air purifiers', TC primary drivers, GM tubes, etc...)
--Low current demonstration topics (e.g. 'Lifters', 'Jacob's Ladders', 'Plasma Spheres', 'Kirlian photography', 'Ion Motors', etc...)
<--Capacitor discharge demonstration: (e.g. 'Quarter Shrinkers'/'Can Crushers', 'Rail/Coil Guns', 'EMP generators', electrical weapons, etc...)

Please be advised that site policy prohibits my response to most inquiries coming under the latter category...
=================================================

Scope of this tutorial
Provision of a minute, 'step by step' procedure for modification of 'heavy duty'
AC LOPTs for serious EHT application/research...

Said procedure having the following principal goals:
-- Improvement of insulation integrity via removal of auxiliary windings coaxial to the EHT winding.
-- Enhancement of versatility via electrical 'floating' of the EHT winding.
-- Appropriate adjustment of reluctance gaps.


The desirability of LOPTs:
Of the commonly available magnetic components applicable to low through medium power EHT production, the LOPT offers the advantages of relatively high power intermittent operation (several hundred Watts per transformer) and useful continuous power operation (to Ca. 150 Watts each transformer under forced air cooling). Moreover, LOPTs' amenability to resonant (and, hence, sinusoidal) drive permits development of systems productive of highly desirable mean output EMFs (˜70% peak) as opposed to the rather low (1% to 5% 'spike' EMF) characteristic of flyback and similar pulse driven/energy storage topologies. Additionally, the inherent output symmetry attending resonant drive topologies facilitates implementation of effective external EMF 'multiplication' schemes.

Prominent among the LOPT's disadvantages are the common expedient of integral rectification/EMF multiplication circuitry and 'end point' grounding schemes --- While the former objection is readily addressed via judicious transformer selection, the latter requires minor 'reconstruction', said procedure being the topic of this tutorial.

A few words regarding the unsuitability of DSTs and their ilk:
Principally
1) Integral components electrically unsuited to general application.
2) Practical impossibility of modification for improved EHT winding to core insulation.

Re: point 1 (above) Although asymmetric drive may permit peak forward (and hence output) EMFs well in excess of the internal rectifiers' PIVs - such is, of course, inapplicable to 'filtered' or otherwise capacitively loaded schemes sans additional external rectifiers - moreover internal rectification greatly complicates cascading of multiple LOPTs for increased EMF and/or development of balanced output schemes...

Re: Point 2 (above)
'DC' LOPTs are constructed as indivisible units sans 'margin' for modification -- moreover (in the case of DSTs) the rectifiers are 'distributed' throughout the winding...

LOPT Selection:
The most desirable transformers are those intended for direct production of (pre-rectified) accelerating potential for large CRTs -- Contrary to common belief such units are yet readily available from long-established electronics supply houses (whom, in my experience, are only too happy to wave 'minimum purchase' and 'wholesale only' policies at the prospect of disposal of what they regard as 'dead stock') --- That said, one should expect to size their purchase so as to offset the supplier's 'invoicing costs'... Prices as low as $20 (USD) per transformer (in reasonable quantities) are not uncommon...

The following images are offered as an aid to recognition of the desired form factor:

Assorted LOPTs typical of the desired geometry:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopts-jpg.101773/

Detail - Axial view:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt2-jpg.101772/

Detail - Transverse view:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/nos_tyre_lopt-jpg.101774/


The modification procedure:
--Please do not commence disassembly of the transformer prior to reading and comprehension of the entire tutorial...

To Begin:
Disassembly of the LOPT unit

=======================

Step Prq_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 frame rail to frame 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 Preq_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 {2}frame '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 Preq_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 {3} (and, hence, {4}from the assembly) -- 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 Preq_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 the lower form leg.

Step Preq_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 {5}inside surface 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 fenestrated uterine 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 {6}≈ 90 minutes at 16°C {7}through 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 {8}of the lower form leg 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.....

{9}

=======================







=================================================


For these purposes we will consider four (coaxial) features of the EHT winding assembly:

To Wit:
(Peripheral to central).
1) The EHT 'tyre' (comprised of the EHT winding proper, potting material and bunting).
2) The Auxiliary shell (a paperboard or polymer 'collar' intervening the central aspect of the EHT winding and the peripheral aspect of the Aux winding...
3) The Aux Winding{s}.
4) The form sleeve (intervening the {10}central aspect of the Aux winding and the ferrite form).

Please note said features in the image below:

Image of intact EHT winding assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_1-jpg.101749/


Step 1) Locate the lug carrying the EHT return:
The EHT return generally emerges with one or more AUX leads from the peripheral circumference of the AUX winding whence they are tied to a shell lug...

In this instance, said lug occupies the 2-o'clock postilion -- The image below shows said leads emerging from the Aux winding immediately below the CCW edge of the lug (as indicated by the ball-point pen) -- of special significance is the extreme peripheral position of the break-out point.

Image of the bundle containing the EHT return.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_2-jpg.101750/

Step 2) Separate and identify the EHT return:

Tasks:
1) Carefully unsolder all leads from the lug identified in Step 1 (above).
2) 'Untwist' and otherwise separate said leads.
3) Using a resistance indicator, check each lead for continuity to the EHT output contact --- the return lead will show a resistance of between {11}400Ω and 1000Ω All other leads should show infinite resistance (i.e. no continuity).

In the case of the demonstration transformer, three leads were tied to the lug -- the {12}resistance examination identified the 38 AWG lead as the EHT return (said lead indicated by the pen in the attached image).

Image of separated EHT return --- Note that the associated lug was broken out of the way.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_3-jpg.101751/

Step 3) Remove the form sleeve:

Please note: Far and away the most significant challenges attending this procedure owe to the 'gossamer' nature of #38 and #40 AWG conductors... From this point onward it will behoove the reader to remain alert to the location of the EHT return whenever handling the assembly - while a severed or broken return lead is not necessarily 'fatal to the cause' - such will greatly complicate matters via the requirement of 'teaseling out' the end of a #40 or even #42 (AWG) lead from the lacquered winding!

Tasks:
1) Carefully dress the return lead out of 'harm's way'.
2) Twist, pry and/or break the form sleeve out from the center of the Aux winding.

Image of EHT winding following removal of the form sleeve. Note the EHT return at ~ "2 O'clock"
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_4-jpg.101752/

Step 4) Remove the AUX winding:

Precautions:
A) While 'unraveling' the Aux winding, apply counter-thrust only to the shell --
as opposed to the tyre!
B) While debriding residue from the '{13}central gap' following removal of the Aux Shell - great care must be exercised is damage to the {14}central layer{s} of the EHT winding to be avoided!

Tasks:
1) Cut all leads attached to all remaining lugs.
2) Using a surgical pick or similar instrument, pry a few 'layers' of the Aux winding into the center such that they may be grasped with forceps.
Image of Aux winding prepared for removal.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_5-jpg.101753/

3) Grasp the the loosened layers and begin withdrawing ('unraveling') the Aux winding -- Taking great care to avoid application of tension to the return lead as you progress toward the periphery.

Image of Aux winding in an intermediate stage of removal.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_6-jpg.101754/

Note: The EHT return will typically be 'laminated' between the penultimate and ultimate layers of the auxiliary winding bunting
4) Cautiously break (not tear!) the bunting material away from the return lead.

In the image below you may observe the end of the EHT return (as per the pen) and its emergence from the bunting in the gap intervening the shell and the deflected bunting {15?}medial to the remaining lug at 4 O'clock

Image of EHT return embedded in peripheral Aux winding bunting.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_7-jpg.101755/


Image of EHT winding following complete removal of Aux winding
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i1_7-jpg.101755/

Step 5) Remove the AUX Shell:

Tasks:
1) Carefully break, crumble and/or fold the auxiliary shell into the '{16}central gap' via symmetrical application of force to the distal {17}labra of same at quadrature to the plane of the return.

Under no circumstances attempt to pry the shell from the interstices!!! Doing so will almost certainly damage the EHT winding beyond repair!

2) having thus loosened the shell, carefully remove the fragments being ever mindful of the return...

Images of the EHT winding following removal of the auxiliary shell...

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_1-jpg.101757/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_2-jpg.101758/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_3-jpg.101759/

Image of EHT winding and debris following removal of {18}form sleeve, Aux winding, and Aux shell:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_4-jpg.101760/


Note: Should the reader's EHT winding be potted in silicone (as opposed to merely 'jacketed' as in the case of the demonstration transformer) it will be desirable to arrive at this juncture sans disruption of the potting material -- Should a breach occur, prompt repair via application of {19}electronics grade RTV is advisable...

Step 6) Prepare The Dummy Shell:

Note: Owing to the 'brittleness' of 'Purell' grade polypropylene, use of a sharp instrument is recommended!

Tasks:
1) Excise the the base of the pharmaceutical vial.
2) Section the (resulting) cylinder longitudinal to its axis.
3) Temporarily mount the dummy shell on the ferrite form -- Verify {20}end clearance {22}≥ 5mm (form pieces in firm apposition) If {21}end clearance < 5 mm, trim the dummy shell to 'compliance' but try to keep {23}end clearance < 1 cm

Image of prepared dummy shell
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_5-jpg.101761/


Image of correctly 'trimmed' dummy shell on leg of LOPT ferrite form:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_6-jpg.101762/

Step 7) Prepare Return Lug:
Tasks:
1) Form a #4 solder lug such that the 'tab' is at a right angle to the plane of the fastener surface.
2) Drill a #66 (~0.83mm) hole through the lug immediately above the bend.

Image of properly prepared lug -- Notice the small (#66) hole near the fastener angle.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_7-jpg.101763/

Step 8) Installation of the dummy shell:

Image of EHT winding at this juncture - note return lead:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_8-jpg.101764/



Tasks:
1) Furl the dummy shell, then position it in the {24}central gap from the side of the winding opposite the return lead such that the 'cut' faces opposite the output 'tower'.
2) Using a stylus, etc, mark the dummy shell at the point {25}distal to the emergence of the return and 5 mm back from the edge of the dummy shell.
3) Carefully remove the dummy shell.
4) Using a drill bit commensurate with a #4 bolt, bore through the dummy shell at the point marked in task #2.
5) Liberally coat the dummy shell and gap surfaces with {26}electronics grade RTV. -- Avoid application of RTV to the return lead!
6) Reinstall the shell as described in task #1, taking care to position the cut opposite to the output 'tower', and the bolt hole {27}distal to the emergence of the return lead.
7) Mount the EHT winding/{28}dummy shell assembly on the ferrite form.
8) Adjust the (linear) position of the winding tyre on the shell such that the former is equidistant from the form piece angles while the end of the shell emerging from the 'return lead side' of the winding tyre extends as far as possible from the winding sans contact with the form piece.
9) Remove the form from the assembly taking care not to alter the relative position of the shell/winding.
10) Manually expand the shell as much as possible -- smooth and 'touch-up' the silicone... --- Again keep the return lead free of adhesive!
11) {29} Allow RTV to cure for at least 72 hours at temps of 7.2°C (45°F) through 15.5°C (60°F) -OR- for at least 48 hours at temps >15.5°C (60°F)

Step 9) Installation of the Lug and connection of the return:
Tasks:
1) Carefully insert the #4 bolt from inside the shell.
2) Secure the lug to the top of the shell as shown in the images below.
3) Solder-tin the end of the return lead.
4) Insert ~ 2 mm of the return lead into the #66 hole near the base of the lug then secure it with solder.

Note: It is imperative that you neither trim nor glue the return lead at this point! - Please loop any slack as shown in the images.

Images of the assembly; Dummy shell & Lug installed, return connected:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_9-jpg.101765/

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i2_10-jpg.101766/

5) Verify that the DC resistance (lug to output tower connector) -- is that measured in step #2, task#3


Anticipated FAQs
Note: the following questions approximate the 'mean' of copious feedback received at this 'stage' during composition of the original draft...

Q) The lug screw head will short the EHT return to the form -- and anyway, who wants the winding rattling around on the form like that?
A) We're not done yet! --- Patience!

Q) One centimetre is insufficient spacing of lug and winding for 50kV operation!?
A) That's why we're going to intervene lug and tyre with a thickness of PTFE in a subsequent step.

Q) Why not trim the return lead to length or at least glue it to the shell?
A) Prior to complete curing of the shell-to-tyre adhesive, and robust securing of the lug, provision for 'immunity' to relative motion of the parts makes good sense.

Q) What do spools of solder and capacitors have to do with rebuilding an LOPT?
A) The extraneous items in the images assist to achieve optimal focus -- especially as regards diminutive objects (IOW I'm using an inexpensive camera).

Step 10) Prepare the CPVC Form sleeve:
Tasks:
1) Cut a length of 3/4" (id) CPVC tubing equal to the total length of the form-leg on which it will be placed (In {30}the case of this demonstration 8.5 cm) See the two images immediately below...

Image illustrating desired sleeve dimension
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_1-jpg.101767/

Image of form and adjacent CPVC section cut as per step #10
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_2-jpg.101768/

2) Cut shoulder stirrups in CPVC Sleeve:
Note: the stirrups must be sufficiently deep as to allow a slight amount of end-clearance when mounted upon the form (such that {31}form piece apposition is assured).

Image of form pieces and 'prepared' CPVC sleeve
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_3-jpg.101769/

Image of form and CPVC sleeve in an intermediate state of assembly
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_4-jpg.101770/

Image of (temporary) fully assembled form and CPVC assembly
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/i3_5-jpg.101771/

Step 11) {32}Permanently install CPVC form sleeve in EHT winding assembly:

Image of components referenced in this step:
(L to R) CPVC sleeve, EHT winding assembly, Form [core] pieces
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/1-jpg.101711/

Tasks:
1) Assemble EHT winding, CPVC sleeve and form as shown (below).
2) Using PTFE shims, center EHT winding assembly about CPVC sleeve (both sides).
Note: While the adhesive does not {33}bond PTFE it is, nonetheless, essential that the shims be so formed as to preclude (interlocked) captivity therein!

Images of mounted and centered EHT winding as seen from 'EHT return side':
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/2-jpg.101712/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/3-jpg.101714/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/5-jpg.101717/

4) Using acrylic-based 'hot-melt' adhesive, tack the CPVC sleeve to the polypropylene shell at several points each side.
5) Remove form pieces.
6) Fill the space intervening the CPVC sleeve and the PP shell with acrylic-based 'hot-melt' adhesive taking care not to disturb the relative positions of said structures!
7) Allow the adhesive at least 60 Minutes to cool/cure.
8) Withdraw the shims.

Image of assembly immediately following withdrawal of shims as seen from EHT return side.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/7-jpg.101719/

9) Fill the 'shim gaps' with acrylic-based 'hot-melt' adhesive.

Image of EHT winding assembly following completed installation of CPVC sleeve.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/8-jpg.101721/

Identification of components referenced in steps #12 through #15 (inclusive):
1) PTFE insulator.
2) EHT Winding assembly.
3) Form pieces.
4) LOPT Frame.
5) Polyolefin (heat shrink) sleeves.
6) Elastic cushions.
7) Frame ligature.
8) Form standoffs.
9) Reluctance gap spacers (see text).

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_partsnum-jpg.101730/

Step 12) Prepare form guides

Prior to proceeding, it is imperative that the form pieces are absolutely free of adhesive residue, etc...!

Tasks:
1) Trim two pieces of polyolefin tubing such that they extend the full inside length of each 'winding leg' of the assembled frame (as shown below).
2) With the sleeves in place on the form, clamp or otherwise place form pieces in firm apposition with close attention to alignment of same.
3) 'Heat-shrink' the polyolefin tubing -- Note: expeditious completion of this step will significantly reduce liability to ferrite breakage (secondary to uneven application of heat) and/or permanent shift of magnetic properties (secondary to excessive temperature)...
4) Allow at least 20 Minute 'cool down' period then carefully disassemble the form such that the heat-processed polyolefin tubes remain installed on each 'half-leg' of a single piece.
5) Trim another sleeve then repeat the above procedure such that one leg is bound by a double layer of polyolefin.

Image of assembled form 'sporting' the unprocessed polyolefin sleeves (Post task #1)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/preshrink-jpg.101742/

Image of form piece following processing of sleeves (Post task #4)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/separated1-jpg.101743/

Image of form piece following processing of second sleeve on (arbitrarily chosen) EHT winding 'leg' (Post task #5)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/separated2-jpg.101744/

Step 13) Fashion and place reluctance gap spacers

Note: Reluctance gaps will be incorporated to reduce liability to saturation (in all cases) and to leave the transformer {34}compatible with 'flyback' drive topology should same be desired... --- That said, this series prefers forward transfer paradigms (as explained in the introduction to this tutorial).

Note: The (.95mm) reluctance gap spacers salvaged from the disassembly process are shown in the "component identification image" for completeness of presentation only --- Based upon core material properties and desired output current, optimal operation requires development of reluctance gaps consistent with the inequality: 0.25mm < Gap < .5mm -- To this end 0.4mm (nominal) PTFE sheet stock will be used.

Tasks:
1) Cut two small disks of PTFE having maximum diameters (as a practical matter, major axises) slightly less than that of the form piece 'ends'...
2) Check actual spacer thickness with a {35}digital caliper -- then verify with a mechanical micrometer.
3) Very lightly smear one side of each spacer with {36}electronics grade RTV.
4) Place each spacer ({37}RTV side down) flat upon each form piece end (inside each polyolefin sleeve).
5) Via firm tamping with a pencil eraser or similar implement assure that the RTV film 'tacks' the spacers to the form piece ends...

Images showing representative spacer and measurement of thickness:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/airgapcal-jpg.101725/
http://forum.allaboutcircuits.com/attachments/airgapmic-jpg.101728/

Image showing correct pre-assembly placement of spacers:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/airgapinplace-jpg.101727/


Step 14) Assemble LOPT

Tasks:
1) Tack elastic cushions and form standoffs to frame then position as shown:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptframechoks-jpg.101732/

2) Verify that the reluctance gap spacers are fast to the form piece.
3) Hold the frame ligature in lengthwise apposition with the utmost facet of the form's EHT winding leg. (i.e. the leg carrying a double thickness of polyolefin).
4) Carefully place the EHT winding assembly over the form piece leg and ligature such that the shoulder stirrup engages {38}the form piece as shown below:

Form ligature in pre-assembly position:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/asm1-jpg.101729/

Views of EHT winding, form piece and form ligature in intermediate state of assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_preasmby-jpg.101731/
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpartialasmby-jpg.101735/

Slowly press opposite form piece into place allowing time for displacement of air from the polyolefin tubes.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpreframe-jpg.101737/

5) Install transformer assembly into frame such that the ligature strap ends extend through the 'ears' of the frame.
6) Very carefully but firmly clamp assembly preparatory to fastening...
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpresoldered-jpg.101739/


7) Solder ligature ends to frame
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/loptpostsoldered-jpg.101736/

Step 15) Install lateral insulator

Tasks:
1) Form a carotid of 0.093" (AKA "93/1000'ths") PTFE sheet stock as per item #1 in the image (immediately below):
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/lopt_partsnum-jpg.101730/

2) Size, shape and fit the insulator to the EHT winding assembly in a manner consistent with the following images but do not apply adhesive at this time.
Note that the insulator must {39}be trimmed to closely fit the shell and extend beyond the distal aspect of the EHT winding by at least 1 cm.

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/final-jpg.101745/

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
http://forum.allaboutcircuits.com/attachments/strikeshldside-jpg.101748/

3) Having properly formed the insulator, 'de-gloss' one side of same using '00' grit emery cloth/paper.
4) Apply liberal quantities of electronics grade RTV silicone to the appropriate surfaces of the EHT winding assembly and the entirety of the 'sanded' side of the insulator.

5) Attach the insulator to the EHT winding assembly as shown in the above images
6) Apply an excess of electronics grade RTV to the exposed side of the insulator and adjacent areas of the EHT winding assembly...
7) Distribute the RTV over the insulator and EHT winding assembly surfaces such that an interlocking bond is established.
8) Position the LOPT 'insulator up' then allow at least 48 hours curing time.



To be continued/refined via edit...

Best regards
HP

 

@Aleph(0)
As regards post #609 -- I see no corrections/suggestions? -- Should you be experiencing difficulty with your connection, please transmit the corrected draft (in 'raw' format) to my gmail addy - whence I'll post it (with attribution/credit) to this thread -- Otherwise get with it girl!!! It's high time we complete and 'go live' with the current tutorial such that we may move on to driver topologies -- Speaking of which, time permitting, I shall attempt to post examples of "bare bones" 'classic' and 'Mazzilli' Royer based implementations (in Ltspice ".asc" format as well as several simulation 'captures') later this evening/early Wed morning

Best regards
HP

 

@Aleph(0) -- Ok... Here's the deal - Inasmuch as Ltspice' library does not include the most desirable/applicable (real world) components Re: the circuits alluded to in post #610 - I am in the process of selecting models suitable to (well-neigh) acceptable simulation -- hence my brief delay in posting the circuits (please expect said posts late tomorrow [Wednesday]) - Be advised also that, as a matter of integrity, etc... said 'schematic files' will include notes identifying the preferred devices!

OBTW
As I understand it, JC's rally closes on the 14'th? -- 'Guesstimating' a distance of ≈ 800 miles and granting a late start and 'distractions' along the way - he should surely return by the 17'th? -- Should you be privy to contrary info please advise... -- It is my intention to post the current tutorial to projects this month -- preferably, prior to -or during- the 18'th -- with or without feedback from JC!

Best regards
HP

 

get with it girl!!!

HP I think maybe I can cuz like I said on other thread my vpn's Germany, Netherlands setting is making it work almost as well as a regular connection!

It's high time we complete and 'go live' with the current tutorial such that we may move on to driver topologies

Amen to that!

I shall attempt to post examples of "bare bones" 'classic' and 'Mazzilli' Royer based implementations (in Ltspice ".asc" format as well as several simulation 'captures')

HP Tnx! Cuz it's the teaser of good things to come that helps us keep our eyes on the prize!

@Aleph(0) -- Ok... Here's the deal - Inasmuch as Ltspice' library does not include the most desirable/applicable (real world) components Re: the circuits alluded to in post #610 - I am in the process of selecting models suitable to (well-neigh) acceptable simulation -- hence my brief delay in posting the circuits (please expect said posts late tomorrow [Wednesday]) - Be advised also that, as a matter of integrity, etc... said 'schematic files' will include notes identifying the preferred devices!

Sounds good, HP! But here's suggestion; Since they're just introductory examples you can dispense with feedback regulator circuitry. Just show inverters and doublers so the main ideas aren't hidden in too many practical details cuz HV newbies want their steak before potatoes

As I understand it, JC's rally closes on the 14'th?

It always starts the Monday after the first Saturday in August and runs until the following Sunday so you're right! JC's intellectual giantfest winds up on the 14'th

'Guesstimating' a distance of ≈ 800 miles and granting a late start and 'distractions' along the way - he should surely return by the 17'th? -- Should you be privy to contrary info please advise...

HP I say no worries! Cuz I'm here to tell you JC's main _distraction_ is a lot closer to home than to SD!

It is my intention to post the current tutorial to projects this month -- preferably, prior to -or during- the 18'th

HP you're sounding like that Heather character in old indie film! How she kept saying _we're almost out of the forest_ for days until everyone went insane cuz of unrealized reassurances!

 

Kind friends

As per Aleph's suggestion, I present these circuits sans enhancements (e.g. 'Q-Spoilers', 'true ZVS' operation enforcement, etc) or auxiliary features (e.g. EMF regulation, OVP/OCP, arc detection circuitry, etc.). Please be advised that both circuits leave room for radical improvement! -- That said, they will preform well-neigh as per their simulation runs so long as the suggested (as opposed to the modeled) semiconductors are used!!!

Note also that I've attached the LtSpice schematic (".asc") files for the circuits presented here...
Please bear with me! - I'll revisit this subject at a later time! -- at the moment I'm 'ankle deep' in every sort of BS! --- (all of which has absolutely no bearing upon AAC nor its staff or membership!)

Here's hoping somebody finds this at least marginally interesting!
Schematic of the 'Plain Jane' high power driver:


Screen capture of a simulator run of the above circuit -- Note that, following the 'bump' at startup, the simulation 'runs true' if the suggested semiconductors are used:



Schematic of the unadorned low-power driver:

Screen capture of a simulation of the low-power driver -- again the simulation is reasonably accurate assuming the real-world circuit incorporates the suggested semiconductors:


Best regards
HP

 

HP Tnx! I can play with simulations of these and post all the questions I know I'll have on here

 

HP I'm hard at work proofing the tutorial as you can see by pr flags on post 609 and I'll post error log when finished! Then I'll have time to explore _generator_ circuits on post 613 But I have this question already which is why bother with classic circuit when so called ZVS circuit's performance is so much better?

 

HP I've done first pass of proofing so plz finish disassembly instructions and ending so I can do final pass
OBTW I've made recommended changes to my copy (which is post 609) except for 15 and 17 cuz they are points of style

Here's proofreading log
1 Needs “<=” instead of just “=”
2 It’s clearer to just say frame ears cuz slots are in frame.
3 “assembly{s}” can be deleted cuz only one is possible in description and its back referenced in parenthetic clause so its redundant anyhow.
4 “From the assembly” fits sentence better than “off of the form”.
5 “Inside surface” makes more sense than “central aspect” in this case.
6 To correct misdisplaying punctuation character.
7 In this case “through” is clearer than “-“ which can be confused with negative sign.
8 To fix ambiguous subject to lower form leg.
9 HP you need to finish core disassembly instructions!
10 Clarification of relative reference.
11 To correct two instances of misdisplaying omega symbol
12 HP I say is better to say “resistance examination” than “continuity examination” otherwise some ppl might use dmm in cont mode which says everything >300 ohms is open!
13 Clarification of relative reference
14 Clarification of relative reference
15 HP IMO “medial” is ok there cuz “central to” is just lame so I left it be but wanted you to know I looked at it
16 Clarification of relative reference
17 HP I get it but some ppl will misread that word and if they’re too busy snickering or thinking up jokes then they’re not paying good attention.
18 For inappropriate capitalization of “form”
19 To bold very important point that it has to be ELECTRONICS grade silicone
20, 21, 23 Removed “-“ from “end clearance” to prevent confusion
22 To repair misdisplaying inequality symbol
24 Clarification of relative reference
25 Clarification of relative reference (distal vs axial)
26 Bolded “electronics” to emphasize electronics grade RTV
27 Clarification of relative reference (distal vs axial)
28 To correct inappropriate capitalization on “Dummy Shell”
29 For all of task 11 added Centigrade/Celsius temps as default for more universal accessibility
30 To correct w/w error (“the” vs “this”)
31 Removed “-“ from “form-piece”
32 Added “permanently” qualifier to avoid confusion from “temporary” qualifier in earlier image description
33 To correct spelling error
34 To repair spelling error
35 Specified “digital”caliper to be clear
36 To emphasize electronics grade RTV
37 Replaced “siliconed” with “RTV” to enhance formality
38 Deleted duplicate word “the”
39 Added omitted verb “be”

 

HP Tnx! I can play with simulations of these and post all the questions I know I'll have on here

Please know that while I am ready, willing and able to assist you with the real-world circuits -- I can be of little help with 'Spice'

Best regards
HP

 

HP I've done first pass of proofing so plz finish disassembly instructions and ending so I can do final pass
OBTW I've made recommended changes to my copy (which is post 609) except for 15 and 17 cuz they are points of style

Many, many thanks! -- I will 'walk through' the log this evening!

 

Please know that while I am ready, willing and able to assist you with the real-world circuits

HP Sweet! Cuz that's just what I want!

I can be of little help with 'Spice'

Ha ha! Join the club! HP I'm thinking world needs a new discipline just to study nature of Spice!

Many, many thanks! -- I will 'walk through' the log this evening!

HP I wish your manners of punctuality were on par with your gratitude!

PS HP just so you can find it, my thread about default ltspice components was moved to _Programmer's Corner_ which was NOT my fault!

 

HP good news! Both 4CM400000AG's tested good on total 20kv on cutoff w/o leakage Also filled jacket with liquid h2o and ran at 50kw for 10 seconds so we know grids worked right too! Andy said super high gain is normal for such low power operation cuz we got 50kw out with just 400W drive on 100Mhz! So now my turn to say YOU'RE WELCOME for encouraging you to salvage them too!

OBTW ltspice thread was _repatriated_ to General Electronics Chat

 

@Aleph(0)
Please email a raw copy of post #609 to my address such that I may readily incorporate your suggestions (i.e. copy, paste, and delete 'flags')

I plan to respond to your other posts (including #616) ASAP! --- Many thanks for advising me as to the tubes' condition! -- At this juncture I request that you please consider them verified good! Which, apart from the obvious, means don't let Andy and Phil 'play with them' any further! - lest 'escape from victory' becomes my mantra!

All the best
HP

PS

So now my turn to say YOU'RE WELCOME for encouraging you to salvage them too!

I've already commended said insistence upon multiple occasions! -- OK already! let's make it official: THANK YOU! THANK YOU!! THANK YOU!!! -- Sincerely!