Homebrew PCBs

Well, my temperature controllers turned up after getting diverted by
Customs.  I wonder if dope growers use these.

They're cute little things, and very simple to set up, I had it controlling
the kettle in about 10 minutes (5 of that was finding bits).

Interestingly they're made in Japan, which would explain why the manual was
in Japanese.  (Of maybe the Chinese are imitating another Japanese company,
like they did with NEC as while back.)  

There seems to be about a million variations of these things, the model I
have is the 'RKC Rex-C100', second from the bottom on this page -
http://www.rkcinst.co.jp/english/product/single2-e.htm

The fun doesn't stop there though.  For that model certain options can get
locked or be missing, for example they can accept a wide variety of sensors,
but for mine it is locked to K-type thermocouples up to 400C.  Various
manuals I'd found online explained how to set that option, it confused me a
bit as mine didn't have it but then I found the correct manual.

I also solved my problem of how to trigger a timer when the correct
temperature is reached.  You can do this with the alarms; you set a low &
high point, so if your target is 150C, you set the low at say 148 & high at
152, and an alarm triggers if it falls outside this range.  Turns out you
can set a 'band' alarm, which will trigger when inside the range, exactly
what I wanted.  Mine, however, is missing the option to choose the type of
alarm, and is locked to 'high' only.  Bugger.  I need the REX-C100FK02-M*DN,
not the REX-C100FK02-M*AN, although why they couldn't have it set in
software is beyond me.

Although similar to this one -
http://www.neufeld.newton.ks.us/electronics/?p=537, you can see the
differences when dismantled.  Instead of a switchmode power supply, it has
the old style transformer.  Wires between the boards are soldered, not
plugs.  While the power supply board is separate, the logic board is
soldered to the display, so it can't be easily re-arrange to fit a shallow
hole.  All that saves a few cents here & there.  At least without the
switchmode supply I might avoid the infamous 'capacitor plague' that
everything else I own has suffered from.

I've no idea why they're on eBay so cheap, but there's no way you can make
something like this yourself for the same price.

Reflow oven builders will find this -
http://www.rkcinst.co.jp/english/pf900/index.html - interesting.  Very
interesting if it's cheap.

Tony