RE: Aquatic Plants Digest V1 #294

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.


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

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

Stephen Morrison