VIC Core built using Ferrite Pieces

To be able to continue my testing I needed a VIC which means I need  ferrite cores and something to hold them.  I decided to build them using ferrite pieces as I could not find anything that even came close to Stan's cores. I even was having a hard time finding a 1 to 20 step up transformer that NAV talks about in his experiments.  The primary and secondary coils in the VIC will provide that.  The rest of this post explains what I am using and how I am building the core holder.  This is the current state of holder with some of the ferrite pieces in place.  Rest of pieces are on order and I am still working of the rest of the holder including the coil sides.  One positive side of this is if it works you can purchase all the ferrite pieces on eBay for less than $35 depending how you buy them. You can even build the core holder with only hand tools though I am also using shop tools as I have them. See Core tubes completed.JPG for current status showing what I am trying to build. I am on using the dimensions and coil information provided in this forum with the exception of the ferrite size (see below) as a starting point.  Main change is to adjust holder to fit the ferrite pieces I have purchased. I tried to find information on the ferrite cores sources and have not been able to find anything that appears to be close in size or shape.  I did find in this forum where some members made a special purchase but I did not start working on this project until after that purchased was made so I am going to attempt to build my own core from pieces as I will need a gap anyway based on what I have read in this forum. My assumption is even though each ferrite half is not a solid piece I will still need a gap between the 2 halves. One of the reasons I am going to try this as looking for ferrite cores I came across a company, do not remember which one, that had a kit of ferrite parts that could be used to protype transformers.  It was basically a collection of standard parts that you could put together to build cores of different sizes.  For example, standard corner pieces that you could then used to stack other ferrite sections on to build a core.  While it appears, this kit has been discontinued I liked the idea.  So, I tried to find separate flat pieces without much luck.  I even purchase some ferrite antenna rods but was not sure how I was going to do a good connection at corners.  I then came across E coil transformers.  They are in 2 pieces one E shaped and the second a flat bar that goes across the E.  I just wanted the flat bars. I purchase 4 sets of 2 for $28 which gave me 8 flat bars.  I was going to use 2 on each side.  After getting them, I think I will need 4 on each long side where the coils go as each bar is slight longer than 1” but dimension of the coils is 1.3” long. This means I will need 2 more sets which give me 4 bars for the ends.  Bar dimensions 4.44mm x 12.40mm x 33.19mm (0.173” x 0.488” x 1.306’’) Note:  After I finished the tubes I went back and looked at the dimensions to find the size of the coil sides and found that the dimensions of the core and tubes where much closer match that I thought them were going to be. I thought about using my tile saw to cut of the legs of the E bars and use them for the ends but while I think that would work I not sure I what to deal with ferrite dust at the cost of 4 more is so little. NOTE PC 40 is 2300 permeability  2pcs PC40 EI33 6+6pins Ferrite Cores bobbin, transformer core, inductor coil  $28. (Link to ebay where I found them. I also have seen 5 pcs for $7 but vender was out so I purchased these. When I decided I need more I purchase 2 sets of 5 for $22 still waiting for those to come.) As I do not have a 3D printer to make the holders for the ferrite cores I started to make them out a of ½” plastic I have had for over 15 years.  I think it was used to make cutting boards not sure as it was given to me. It is slightly bigger that width of the bar so should make a nice box.  I have already cut sample pieces on my table saw 2mm thick that appear to have enough structural strength.  I could cut them thinner but not sure I should.  I have already done a glue test using vinyl and plastic cement and an epoxy plastic cement neither worked well on this material.  If I can not find a glue that works with this material, I will purchase a thin piece of plexiglass as I know I can get glue that works with it.  Plexiglass may be a better option as it will be easier for me to make the coil side pieces out of it. This would also better option for people without a table saw as you can cut it with scribe tool plexiglass. To get a nice square corner I used my small laser saw mitre box to hold pieces while glue sets.  Use wax paper to keep glue off box and ferrite piece, not shown it picture. Picture below shows parts being used. There are 4 of the bars on piece in mitre box.  The black pins are oval so they can be turned to clamp item being worked on. I am hoping this will work as the cost of the spools with frame built in and the ferrite cores will be less than $100 without wire. Even if it doesn’t it will give me practice winding coils and should work well enough for me to do some testing will primary and secondary coil. “Test of VIC spool build.jpg” shows the E pieces and how I am assembling tubes. Wrapping the tube with wax paper kept glue off ferrite pieces and gave enough space for them side after cleaning off excess glue. I could not find a glue that work on the white material, so I make strips out of plexiglass 0.1 inch thick.  I just happen to have some that I purchased at either Lowes or Home Depot (don’t remember cost guessing $20-$30).  I had purchased it to go around my wife’s sew machine to close out gape between it and her sew machine cabinet.  She did not need it any more has a new machine different size. Couple of pictures of where I am at and a couple of constructions notes.  I stated above I cut strips using table saw to get straight and square edges that were just slightly larger than the with of the ferrite cores then glued on caps on edges first one being glued in picture above. I then put wax paper around ferrite core and glued the other side to bottom forming a u channel.  Because I did not want to try to cut the bottom and top narrow on my table saw this left a ledge on top and bottom that needs to be cut off.  Tried to do it on my table was but without make a special gig it did not work very well had get my fingers to close to blade.  Instead I use my disk sander and that worked well.  I also used my disk sander to bevel the edge to top and bottom pieces to 45 degrees about half the thickness of sheet.  I then used a small file to round the edges that worked very well.  You could do all this just using a file or sandpaper, but the disk sander made it go much quicker.  Note:  If you have problem making straight edges you could use factory edge and glue that side to piece next piece is then glued to second. Keep doing this going the same way.  Last piece is then glue to third piece and first piece’s factory edge.  You will have 4 pieces sticking out from tube that can them be trimmed back not critical as these edges will not be glued and will be rounded anyway. Just want to point out this can all be done with hand tools just takes longer.  I will use coping saw to cutout hole for the coil sides. The “Core piece and side tubes full size.JPG” picture shows one of the small files I used and the wood piece I made to push ferrites in and out of the tubes.  I do not have all the ferrite pieces yet, but I just ordered 10 more from eBay $22. “Core pieces inside tubes.jpg” show ferrite pieces inside tubes to show what it will look like; the end ferrites are just setting on a piece of plexiglass as I had not finished those tubes yet.  Note: The picture shows the ferrite overlap and the extra space needed for the side of the end tub (see small piece of Plexiglas on left side sticking up). “Core pieces inside tubes.jpg” shows what it will look like front the ends. “Core tubes completed.JPG” shows all 4 tubes with some pieces to show layout – waiting for more pieces to arrive.  Pieces on the ends need to stick out slightly to make good contact with side pieces. Have not started on coil sides yet or brackets to hold it all together.  I plan to add means of putting pressure on sides and ferrite pieces to keep ferrite contact tight.  (I dropped one of the pieces and it broke, but I ordered extras).  I left the side tubes long for now as not sure how big of a gap I will need. Though I expect that if I make the side tubes flush with the outside of end tubes I will have enough room to have a big enough gap but no one ever provide gap size information that I can find. Current layout is for zero gap on sides. I will need something to go into gape in middle of the 4 side pieces not sure what I will use yet.  I currently plan to just let the side pieces stick out slight past end ferrite but you could add spacer on inside edges of end tube where plastic is sticking up in the end view picture.  This would make ends flush.  Could do this on just one end and use a spacer the same thickness of the gap in the side pieces or both ends if you need a larger gap. Next steps is to build the coil sides pieces should be fairly each using drill and coping swap. Drill four corners and use saw to get holes slight smaller than needed.  Then file to correct side.  I know this works as that is how I make plexiglass piece for my wife’s sewing machine. I am also working on make a coil winder setup to hold the tubes.  I have a coil winder, but shaft is two big to fit into tubes.  I am making a holder on a separate shaft that will be driven by a toothed drive belt.  I am using toothed gears of the same size so I can use the counter on the coil winder. Gears I purchase come is same outside dimension and tooth count but have different inside dimensions.  Made by 3M found them on Amazon had to drill out the one for the coil winder as it not metric but found one that was close in size.  That project still in work designing and testing as I go.