---Tutorial under development---
Last Action: Nov 2 2017
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LOPT preparation tutorial- Volume {B} (Step 2-12 - end of document )
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Step 2-12) 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-process 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)
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###Improve descriptions below to indicate images follow separation of form pieces####
Image of form piece following processing of sleeves (Post task #4)
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Image of form piece following processing of second sleeve (on arbitrarily chosen) EHT winding 'leg' (Post task #5)
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Step 2-13) 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 compatible with 'flyback' 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 (0.015" nominal) PTFE sheet stock will be used.
Tasks:
1) Cut two small disks of PTFE having maximum major axes slightly less than that of the form piece 'ends'...
2) Check actual spacer thickness with a mechanical vernier micrometer (Resolution = 1 um -OR- 1/10,000 inch) note that a 'metric' instrument offers slightly finer resolution (inasmuch as 0.0001"=2.54 um)
3) Very lightly smear one side of each spacer with electronics grade RTV.
4) Place each spacer (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...
Image showing representative spacer and measurement of thickness:
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Image showing correct pre-assembly placement of spacers:
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Step 2-14) Assemble LOPT
Tasks:
1) Tack elastic cushions and form standoffs to frame then position as shown:
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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 the form piece as shown below:
Form ligature in pre-assembly position:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Views of EHT winding, form piece and form ligature in intermediate state of assembly.
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vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
5) Slowly press the opposite form piece into place allowing time for displacement of air from the polyolefin tubes.
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6) Install transformer assembly into frame such that the ligature strap ends extend through the 'ears' of the frame.
7) Very carefully but firmly clamp the assembly preparatory to fastening...
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8) Solder ligature ends to frame
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Step 2-15) Install lateral insulator
Tasks:
1) Form a cardioid of 0.093" (AKA "93/1000'ths") PTFE sheet stock as per item #1 in the image (immediately below):
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
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 be trimmed to closely fit the shell and extend beyond the peripheral aspect of the EHT winding by at least 1 cm.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
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.
=== Part 3 --- Operational testing ===
<<< part 3 under construction >>>
Last Action: Nov 2 2017
/////
LOPT preparation tutorial- Volume {B} (Step 2-12 - end of document )
/////
Step 2-12) 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-process 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
###Improve descriptions below to indicate images follow separation of form pieces####
Image of form piece following processing of sleeves (Post task #4)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Image of form piece following processing of second sleeve (on arbitrarily chosen) EHT winding 'leg' (Post task #5)
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Step 2-13) 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 compatible with 'flyback' 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 (0.015" nominal) PTFE sheet stock will be used.
Tasks:
1) Cut two small disks of PTFE having maximum major axes slightly less than that of the form piece 'ends'...
2) Check actual spacer thickness with a mechanical vernier micrometer (Resolution = 1 um -OR- 1/10,000 inch) note that a 'metric' instrument offers slightly finer resolution (inasmuch as 0.0001"=2.54 um)
3) Very lightly smear one side of each spacer with electronics grade RTV.
4) Place each spacer (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...
Image showing representative spacer and measurement of thickness:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Image showing correct pre-assembly placement of spacers:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Step 2-14) Assemble LOPT
Tasks:
1) Tack elastic cushions and form standoffs to frame then position as shown:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
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 the form piece as shown below:
Form ligature in pre-assembly position:
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Views of EHT winding, form piece and form ligature in intermediate state of assembly.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
5) Slowly press the opposite form piece into place allowing time for displacement of air from the polyolefin tubes.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
6) Install transformer assembly into frame such that the ligature strap ends extend through the 'ears' of the frame.
7) Very carefully but firmly clamp the assembly preparatory to fastening...
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
8) Solder ligature ends to frame
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Step 2-15) Install lateral insulator
Tasks:
1) Form a cardioid of 0.093" (AKA "93/1000'ths") PTFE sheet stock as per item #1 in the image (immediately below):
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
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 be trimmed to closely fit the shell and extend beyond the peripheral aspect of the EHT winding by at least 1 cm.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
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.
=== Part 3 --- Operational testing ===
<<< part 3 under construction >>>
