DIY aquarium temperature controller

Has anyone seen plans or an article in any of the journals about constructing a
temperature controller for aquarium use?  I have seen quite a few commercially
available units that will do what I want, however the cheapest one I have seen
is close to $200 and it seems that it would be possible to make one for much

Basically the device would need a water proof temperature probe, some type of
trimming device for calibration, and the ability to switch a 400va power supply.
A nice to have, but not essential feature, would be an LED temperature readout
or possibly a way to temporarily use a multimeter to measure

*Mike Roberts - mike at microspan_com
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