RE: [ST] Electrics

["Chris Strizver" <strizver@xxxxxxxx>]

Rich-

First, check your math again. 3.9 ohms at 12V gives only 36 watts; at 13
volts, it gives 43 watts.

I can't confirm or deny that nichrome wire would be more reliable. I wired
my liner up in Feb. this year with no problems yet. I just don't see the
heat cycles being all that extreme.

One problem that I see you having is a soldering/wiring nightmare. At first
I thought that for any individual area of your body to feel heat, it would
need all four wires working together. After some drawing I think that is
incorrect. What I do see you needing to do is separate your liner into four
sections and run one 6ft. length through each of them. Then you'll need to
connect them all in parallel with the terminations in different locations.
You will need to crimp or solder 8 connections verses 2 for a one continuous
wire circuit.

In addition, I don't think you'll have enough wire. Each sleeve, for
example, would need to be one section. My sleeves were 20 inches long. A six
foot length of wire would make only 3.6 loops, which isn't going to produce
very even heat. You'll have a total of 36 linear feet of wire to run. By
comparison, I used 50 linear feet and wished I had about 5 more!

You might want to think about this instead:

Use four 12.5 foot sections of 22 gauge nichrome wire.

- --22 gauge wire is 1.027 ohms/foot.
- --Each section at 12 V would yield 11.21 watts. 12V / 12.8375 ohms = .9348
amps.  12V X .9348 amps = 11.22 Watts
- --Four sections at 11.22 watts would yield a total of 44.87 watts.

You would then have 12.5 feet per section to route your wire, instead of
only 6.

One advantage I can see of doing it this way is that the bigger wire is less
delicate and easier to solder. You still have the nightmare (IMO) of
connecting all the sections in parallel.


Anyway, for anyone who's interested, you can look for a supplier of the
tephlon coated wire at www.graybar.com or www.anixter.com. You can also go
to www.newark.com, but I'd use them more as a way to find suppliers like
Graybar and Anixter, as their shipping is outrageous and not disclosed
before you get your order.

Hope this help, Rich!

Chris Strizver


 -----Original Message-----
From: 	owner-st@xxxxxxxxxx [mailto:owner-st@xxxxxxxxxx]  On Behalf Of Rich
Uncle
Sent:	Thursday, September 27, 2001 7:08 AM
To:	ST@xxxxxxxxxxxxxx
Subject:	RE: [ST] Electrics


>
paraphrased from
http://www.ibmwr.org/otech/heatedclothing.html...  The
26ga nicrome (this is the thickness I ordered) is
2.598 ohms/foot, so 4 six foot strands connected in
_parallel_ yield about 4 ohms. (Each 6 foot strand
giving 15.58 ohms, 4 in parallel giving 3.9 ohms
total, for about 46 watts.)

The key is wiring it in parallel.

15.58 Ohms per circuit / 4 circuits = 3.895 Ohms

Also, the John Deere man charged me about $20 for the
RE11344 plug.  I guess prices have gone up since 23
Aug 1996 when the www.ibmwr.org article was written.

12 Volt LED, mini toggle, rubber cap for toggle, small
"project" box (hmmm... I wonder if my BSA "project"
would fit in there), and "lamp" type 2 conductor wire
purchased from Radio Schmack yesterday. Just waitin'
on the nichrome whar.

Rich




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