gEDA-user: furnace controller follow-up

[DJ Delorie <dj@xxxxxxxxxxx>]

For those who are curious about the furnace controller, here's the
stats for the last 48 hours:

http://www.delorie.com/house/furnace/20060116.png

Yes, the temp dropped 50 degrees in 12 hours.  The gap was a 2 hour
regional power failure.  I continue to tweak the control software as
needed; recently adding "run fan occasionally" and "manage humidity
better" features.  Noise and glitches continue to plague me
occasionally, but then again, the board is mounted next to an
electrostatic filter.

The system has cost me about $500 so far, but it's given me enough
information to realize that (1) the AC needs to be serviced in the
spring, and (2) running the woodstove saves me 50% of my fuel oil :-)
Yup, it's paid for itself and it's next upgrade already!

The plan is, once I catch up on other projects and have some time, to
redesign the controller board with a CPU on it so that I can get rid
of the separate PC.  I'd like to have the ethernet cable go right to
the furnace.  So far, the design is to have an R8C/Tiny CPU for each
zone, and something running linux (xscale/dram/CF perhaps, like a
gumstix) to coordinate everything.  All on a 3.5 x 5 board.

So now you know why I'm still interested in gEDA/PCB :-)

FYI I've been building a spreadsheet of current prototype PCB fab
houses, there are a number of inexpensive options these days, at
least, if you don't mind dealing with foreign businesses (and if you
can figure out their pricing structure from their web page).

For example, Sierra Proto Express offers: 4 layer 6/6 w/ mask and
silk, up to 60 sq in, $51/ea for qty 3+.