Thursday, February 25, 2016

Formers for your coils - antenna coils - transformer

You can make your own coil formers from any thick craft paper. You can use a round core or square or rectangle to fit your need. Plastic tubing and pipe work well. Wood dowel can be obtained in a lot of different sizes. I took a piece of 3/4" lumber and ripped a strip 3/4" wide to make the square forms.
Here are a couple of the ones I've made.
For these I'm using a piece of 1" pipe and some "O" rings that fit the pipe snugly.
I put some glue on one side of the paper strip and wrap it glue side out onto the pipe. The tightness of this step determines if the coil will friction fit the pipe or slide freely.

I cut two paper rings slightly larger than the pipe OD. Slip one one the pipe followed by an "O" ring on each end. Just a fine bead of glue on the inside at the junction of the tube a ring. You can stack rings and glue them together to get the stiffness you desire.
If you need several just keep stacking them on the core as needed.

The square forms are detailed in Babani's book. I'm showing a couple just because I had them laying on the bench. The round one were a magazine cover and the squares were a cracker box. You can use whatever is handy.
The same process using some 1/2" tubing.

The coils will slide on the core and go inside the larger. Could be some variable coupling scheme in the making. These are ready for a hot wax dip.  Let your imagination soar and build something!

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