View single post by JKeen
 Posted: Aug 9th, 2017 07:18 PM
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Joined: Aug 9th, 2017
Posts: 4
flybd5 wrote: But no mention of materials or other specs. It's also wrong. You can't get 5000 ohms out of a coil that small, even with the smallest available wire. To get 5,000 ohms with 43AWG enameled wire would take a coil with 30,000 turns of wire 1,477 meters long.

Where are the recordings? Have they ever made them available for scrutiny
I used a sewing kit spool  with an inner diameter of 11mm with 46 awg wire. According to a coil wrapping calculator designed for e-cigarette users (link is below), it should theoretically take 10,656 windings. For me it varied from 9000 to over 15,000 windings to get a target resistance of 5000 ohms. I measured the turns using a calculator that was modified with a reed (magnetic) switch.  I'm guessing the quality controls on such a fine wire are hard to maintain in manufacture. It was so fickle, that I gave up on winding in one attempt because I was at 15,000 winds, and theresistence was only at 3.5k-ohms.

As for the spools that finally made it into the device, one came out to about 4.7 K-ohms and the  other at 5.3. They both neatly fit into the .75x1.25x2.75 inch dimensions that I and Scole group respectively constructed our acrylic containers with. I had to burnish away the coating on the magnet wire in segments to measure the resistance as I wound it. It was very cumbersome, and I had about 20 failed attempts. Sometimes the the wire would break as I wound it. Sometimes it would get caught between the chuck of my fiscar hand drill and the spool. I completed good 5000 ohm coils at times, only for it to be botched up somehow after soldering up the leads to the washers that endcap the spool. It was such a headache.

If I attempt this again, I will probably use a slightly thicker gauge like 43 awg, since its commonly used in guitar pickup construction. The actual number of windings will more likely match the calculations, since there's more quality control exercised over it. It probably won't snap as much when I'm winding it, either, because its thicker. According to the calculator, an 11mm spool will take about 21,000 windings. That really doesn't tell me whether it will fit or not though.I have to calculate the volume that this much 43 awg wire occupies. Even if its over the capacity of the spool, you can bulge the center a little bit as you wind it to fit more. I might try 44 or 45 awg as well.

Coil Calculation Website

Last edited on Aug 9th, 2017 07:33 PM by JKeen