RE: Aquatic Plants Digest V1 #294

• To: Aquatic-Plants at actwin_com
• Subject: RE: Aquatic Plants Digest V1 #294
• From: MORRISON at FNALV_FNAL.GOV
• Date: Thu, 7 Sep 1995 14:31:55 -0500 (CDT)
• CC: "FNALV1::MORRISON"@FNALV.FNAL.GOV

STEVEN R AMOR asked about cable for ugh with a specific resistance per unit
length.  Here is a chart for nichrome wire that I got from the mailing list
some time ago.

     Nicrome

Gauge     ohms per cm
---------------------
10       .0021281
12       .0033751
14       .0054054
16       .0085116
18       .0138383
20       .0216210
22       .0346040
24       .0548088
26       .0875760
28       .1394328
30       .2214000

When I built my DIY cables for a 20gal tank I used 12 feet of 22 guage
nicrome wire enclosed in airline tubing for insulation. I attached about
6 feet of 18 guage regular wire to each end for feeders. Two feet of each
feeder wire is inside the airline tubing also.

The cable has a resistance of about 12.6 ohms and my transformer puts out
21 volts for a ugh of 35 watts (v^2/r).  

With a mechanical timer set for 1 hour on / 2 hours off, the tank has been
a steady 82-83 degrees all summer. Probably should have used a little less
wattage.

Steven, did  you build your digital temperature controller?  If so do you 
have plans or drawing you could post?


Thanks,
Stephen Morrison

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