tapping enamel wire

I spent some time today reading the first installment of The Impoverished Radio Experimenter. The author describes how to wind #24 enamel wire around a Quaker Corn Meal box. He mentions "tapping" the wire at certain points and I do have some idea of why he would want to do that and at what locations along the wire, but I'm unclear about details of how the actual tapping is supposed to be done. For example, is one supposed to cut the enamel insulation and solder a lead to the wire there or is there some kind of clip that will penetrate the enamel and make the connection?

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Ignorantly,
Allan Adler 
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Allan Adler
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One way is to stop winding where you want a tap, make a small loop and twist it, then continue winding so that the twisted loop sticks out at right angles from the coil. You can then scrape the enamel from the tap loop with sandpaper.

The crystal set I built as a kid was from a kit that had a sliding-ball tap on the coil; the turns were spaced so that sanding the enamel from a strip along one side didn't short the turns.

Reply to
Stephen J. Rush

Allan,

One technique is to use a narrow strip of cardboard the length of the coil form (oatmeal/cornmeal box in your case). At each point where you want a tap, run the wire over the cardboard, then lift the cardboard and continue winding until the next tap, when you fold the cardboard strip down and again run the wire over the cardboard ... repeat as needed. When you're finished with the coil, you can use sandpaper to remove the enamel from the taps for soldering. I notice that someone else suggested making loops, which is also a common technique.

Northe

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Northe

Thanks to you and Stephen Rush for the helpful answers. Now all I need is some #24 enamel wire. I have very bad luck using electronics suppliers' websites with my ancient browser. So, maybe I should start collecting catalogues, if I can get them for free.

I also built a crystal set when I was a kid, but I learned nothing from the experience. It was just a kit, no explanations other than how to build it. If I did it again now, things would be different.

I also like the Impoverished Radio Experimenter's discussion of building your own variable capacitors. He doesn't make it clear, though, how one attaches the plates along the axis.

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Allan Adler 
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Allan Adler

Yukio YANO

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Yukio YANO

It doesn't really matter, as long as the plates move together and are electrically connected. I don't have that publication, but if you're talking about the usual "breadslicer" variable air capacitor, you could drill a hole in each plate and stack them along a threaded rod with washers between them, then clamp the stack with two nuts. You could build the stator the same way, with differently-shaped plates to put the mounting hole on a tab at the edge of the semicircle instead of the center. The washers are probably the easiest way to get uniform spacing.

Reply to
Stephen J. Rush

No need for an ancient browser Mozilla works for most things and will keep you secure - there's a lot of "extensions" to customize the functionality like "no script" and "ad blocker." No script blocks by default so you have to allow scripting for some shopping.

I keep a Netscape 4.7 around

Opera is free too.

Allelectronics has a paper catalog Electronic Goldmine has a paper catalog and plenty of surplus magnet wire selling for close to scrap prices Edlie electronics - paper and some really old stuff but if you need ferrite rods they have them American Science and Surplus Jameco limited stock but better prices than the big guys As well as Newark, Mouser, Digikey - bigger than phone books these days

We got some pretty good results using sliders on coils for crystal sets. Particularly for antenna tuners - maybe the shorted turn problem is over hyped?

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default

You may want to make a small loop at each tap point and twist it. Then you can continue winding your coil. When you're done winding, go back with sandpaper and carefully remove the enamel from the loop. You can then solder tap wires or use an aligator clip lead to select a tap point.

Reply to
Anthony Fremont

Oops, I should have read the rest of the thread before responding.

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Anthony Fremont

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