Interesting video for the DIY RF/IF coil winders out there

[retailer]

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

[Dave757]

Hi,

Wow, that's impressive!

Kind regards
Dave

[Craig Sawyers]

Want one!

[David G4EBT]

Superbly conceived and engineered.

Though it's based on the simple 'Morris' hand wave-winder of the 1930s, it incorporates a 'heart-shaped' cam, which is necessary to get a straight line traverse of the wire from left to right and vice versa. The heart-shaped cam can be seen 45 seconds into the video.

On his website, he explains the design concepts and the complexities of coil winding, and at 2.47 into the video shows how - in his example - the turns are air spaced and he refers to 'honeycomb' coils'.

https://technitoys.com/a-homemade-pr...f-coil-winder/

Much depends on the desired inductance for a given physical size of coil, but one of the challenges in using a home-brew 'Morris' wave winder, one of which I made, is to get the waves to lie alongside each other, close-wound, like the coils of yesteryear - Osmor, Denco REP et al. High inductance for their physically small dimensions.

What you end up with is a coil like the one, at 16.3 mins into this video:

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

It looks neat enough, but will be low inductance, which may be fine for an HF RF coil, but not if what is wanted is, say, a physically small high inductance LF choke. I think in part, that may stem from using a simple offset cam as shown in the pic below, rather than a heart-shaped cam.

The pic below is a test coil I wound on 12.5mm Paxolin rod, which has 500 turns and an inductance of 3mH. The wide spacing of the turns can be seen. No amount of fiddling to adjust the number of waves per turn makes any difference.

The only example I've found on youtube of a home-brew coil winder which makes close-wound wave-wound coils is the one depicted in the video below, of an impressive multi-pile LF choke, which the designer refers to as 'honeycomb', so maybe something is lost in translation. Each pile looks to be only maybe 5mm wide yet 1cm high, with the turns not collapsing. Total inductance 39mH. Very impressive:

https://www.youtube.com/watch?v=tg67CvbcHaU

Pic 1: 3mH test coil (500 turns).
Pic 2: Example of a simple offset cam as in the Morris Coil winder. (Not heart-shaped).
Pic 3: The finished coil on the home-brew Morris Gingery replica winder.

[retailer]

The machine being made almost all made with 3d printed parts is a great effort, there is a book that I downloaded from the internet archive titled Coil Winders by Geo Stevens - I believe they manufactured coil winders and it has a a lot of info rf coils and how they are achieved with mechanical equipment (cams and gears). I can't attach a copy here as it is way over the limit size wise but I have screen captured a few odd pages.

[QUOTE=David G4EBT;1415864]

The only example I've found on youtube of a home-brew coil winder which makes close-wound wave-wound coils is the one depicted in the video below, of an impressive multi-pile LF choke, which the designer refers to as 'honeycomb', so maybe something is lost in translation. Each pile looks to be only maybe 5mm wide yet 1cm high, with the turns not collapsing. Total inductance 39mH. Very impressive:

https://www.youtube.com/watch?v=tg67CvbcHaU

This machine I see uses a servo to drive the wire traverse, the type of servo used in model aero-planes to operate flaps and rudders - the servo would be driven by some sort of cpu - Ardunio or Picaxe, not sure if the builder used mathematical equations or a look up table, even though the mechanics of the winder look very simple it does do an impressive job.

[retailer]

It would help If I included the screen grabs

[Craig Sawyers]

The full book from which those extracts are taken

http://www.vintagewindings.com/gen%2...%20Winding.pdf

[Chrispy57]

A big thank-you to Retailer and Craig for highlighting and linking to this great resource for all of us amateur coil-winders on the Forum. Much appreciated guys!

Cheers
Chris