Modify an ETD49 bobbin for 2 sections

They seem to exist for other core geometries? Are you stuck with a ETD core?

Specify that that fiberous spacing tape be used to separate layers of each winding. Probably tedious since they'll have to stop for each layer, but better than hacking a divider. (Even better would be just finding the right thing in any core style, as Mike said.)

Looks to be margin / mat tape:

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

Thanks guys for your input. As far as I know, using the ETD49 core is stuck. There are interesting to use tape to build up a distance , but there will be a hell of winding it. I need only 0.1 inch (2.54mm) thickness of this wall. I think I have to recalculate all facts and come up with new ideas.

One approach is to half-fill the winding space with a couple of lumps of wood or whatever, held in place by screws or tape, then wind the other half of the space with self-bonding wire.

Once you've got the first coil in place, feed enough current through it to get it hot enough to activate bonding agent, take out the spacer, put in whatever washer you need to space off the second coil, and wind it into the remaining space.

It might pay to put the spacing washer in early, next to the spacing blocks, before you start winding at all - that way you aren't worried if the self-bonding wire bonds to the spacing washer as well as itself.

A slightly messy approach, but practical. Self-bonding wire is handy in a lot of off-beat applications. I think Cambridge Instruments used it in beam-deflecting saddle coils.

I had no idea such wire existed. Thanks for the post.