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Re: WIRE CHART

Subject:       WIRE CHART

>>From richard.quick-at-slug-dot-org Wed Mar 27 01:23 MST 1996
>>Received: from uustar.starnet-dot-net (root-at-uustar.starnet-dot-net [199.217.253.12]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with SMTP id AAA07898 for <tesla-at-grendel.objinc-dot-com>; Wed, 27 Mar 1996 00:51:07 -0700
>From: richard.quick-at-slug-dot-org (Richard Quick)
>Subject: WIRE CHART
>Date: Wed, 27 Mar 1996 04:45:00 GMT
>To: tesla-at-grendel.objinc-dot-com
>
>* Original msg to: brad.alheim-at-the-spa-dot-com
>
>Quoting brad.alheim-at-the-spa-dot-com:

<big snip>
 
>> questions.

>> I've got a LARGE roll of #22 Formvar coated wire I bought 
>> surplus from a company I used to work for. The only drawback is
>> that it was from the Vietnam War era when copper was expensive
>> and this wire is copper coated ALUMINUM. (it was intended for 
>> TV yokes) I haven't measured the insulation thickness yet, but
>> I've been wondering if there could possibly be some drawbacks 
>> to using this for a secondary coil (it does solder nicely, 
>> though)

>I see no problem at all with using this wire. The AL core will
>have a higher DC resistance, but the RF currents were are dealing
>with are severely affected by skin-effect, meaning the RF
>resistance of your particular wire is probably not going to be
>significantly higher than solid copper of the same gauge. At
>Tesla coil frequencies the depth of penetration due to skin
>effect is not going to be much over a few mils. Since beginning
>projects (lower power-higher frequency) generally run at least a
>100 kilohertz or so higher in frequency than intermediate/
>advanced coil systems, the skin effect at these higher
>frequencies will reduce the depth of penetration a bit more.

>The bottom line here is: wind the wire up! 

<big snip>

>Richard Quick



I concur with Richard's analysis.  I got a good deal on a 20 mile 
roll of 100% aluminum #22 AWG enamelled wire and I wound a few 
secondaries on 4.25 inch O.D. PVC to try.  I compared these aluminum 
secondaries to some I had made with #26 AWG copper enamelled wire.
I don't have any hard numbers, just observational analysis.  I'd rate 
the aluminum coil at about 75% performance of the thinner copper 
wound coil.  Note however that the aluminum coil that gave an 
identical inductance, because of the wire diameter difference was 
about 30% longer physically, changing the aspect ratio and number of 
turns, and therefore the distributed capacitance function. These 
factors make a direct comparison less meaningful.  Splash a 
little Cu on top of the ol'Al and I'm sure that it would be right up 
there with solid copper wire, espacially as R.Q. points out, coils 
wound with this type of wire are generally smaller coils, operating 
at hundreds of KHz where the skin depth penetration is thinner.

By the way, don't boo-hoo the use of wimpy #26 copper.  I used it because I 
found a bunch again for the right price for my small coil, but check 
this out!  4.25 inch  O.D. secondary, wound length 22 inches, close wound. 
 3" x 24" smooth aluminum torroid.  Cap= 0.008 ufd.   Single 15KV 60 MA 
neon x-fmer.  9  gap static quench gap (this of course is part of the key!)  I 
measure 52 inch point to point discharges on a good humid day!!!
The same power supply and primary, re-tapped to resonannce was giving me 36 
inch steamers from the same diameter #26 copper coil just 14 inches 
wound length!, (with a smaller toroid).  I wouldn't recommend #26 above
1KVA though as I think the resistive losses would start to hurt performance.

Happy coiling,  R.W.S.