There will be some eye candy here soon, but for now you'll have to make do
with information in the roar (rarrrrgh!)
The network Coffeepot project - status updates:
January 27, 1999 --- I finally got around to putting the coffeepot back
into a semi-functional state yesterday morning. I replaced the metal base
cover, and ran 24 cups of water only through it to prepare it for service,
and clean out any accumulated dust. For some reason the water reservoir
smells a little unusual. Maybe it goes away with use. Everything seems
to work fine though. I stress that I haven't added any additional
circuitry yet... I was just getting sick of it lying around and not doing
anything. I'm thinking of taking it down to the lab tomorrow, and working
on it from there, so it can at least serve its primary purpose while being
modified. We'll see :-). More again soon. It might make its first cup
of coffee tomorrow - I'll give full details then.
January 20, 1999 --- The coffeepot project has entered an idle state for
now. It's still sitting on my floor, taken apart, and waiting for me to
find time to wire it up. I might work on it this weekend, if I get a
chance. It's just a matter of sitting down and hacking out some prototype
boards and code.
December 8, 1998 --- The quest for online coffee is finally underway.
I purchased the coffeepot this afternoon. Along with a friend, I've
already begun the process of dismantling it to adapt it for our purposes.
Several interesting things have happened so far. Firstly, our attempts to
open the bottom of the coffee maker were thwarted for a while, due to the
proprietary screws used to secure the metal base to the plastic body. We
finally became frustrated, and used a pair of bolt cutters to sever the
plastic cylinders that held the screws in place. After this was
completed, the bottom came away easily. We were surprised to find that
in contrast to the annoying exterior, that the interior was remarkably
well designed. We were extremely excited to discover that the main
display and control panel circuit board was designed in such a way as to
make modifications simple. Each touch switch has four protruding gold
pins that extend approximately 1.5mm from the board, which should make
wiring the relays to control the coffeepot easier than we expected. We'd
been expecting solder joints that we'd have to melt and rewire. Another
feature of the circuit board is that it is one of the most well diagrammed
and labeled that I've ever encountered. Every wire and switch is clearly
marked with its function, as are the optional jumper connections. We were
excited to find that there was a jumper on the circuit board to allow 24
hour times in the display and programming (presumably for European
markets or MIL coffeepots). It's also interesting to note that
Proctor-Silex claims on their page that the coffeepot operates on 120V AC
60hz only. We found this to be incorrect. A jumper exists on the control
board that allows the power frequency to be changed to 50hz.
Additionally, the power relays and other circuitry on the board clearly
state that with the above modification, it's useable up to 250V AC, 50hz.
So far, our main problem has been with the heating element. It consists
of four parts. The first is a black plastic shim that fits around the
heating plate. The heating plate has a central screw that fits into the
base of the coffeemaker (or did, until my friend broke it :P). The bottom
of the heating plate is covered in heat sink grease. Touching the hot
plate is the heating element, which cycles out of the main tank into the
brewing compartment, heating the coffee that's already present as it
boils. The heating element has a thermistor mounted on it, with two
thermal fuses in series connected to it. It's designed to prevent an
overheat, and will shut off the power if such an event occurs.
Underneath the heating element is a metal shield, whose purpose appears to
be to guard the circuitry and wires from the heat generated by the
element.
There's plenty of space within the coffeemaker for devices also. All in
all it's a good machine, even if I did have to attach the heater baseplate
back onto the element with paperclips.
I'm going to work on it further tomorrow (12/09/1998). Based on the
layout of the machine, I'm developing ideas as how to best implement the
telemetric elements that will be needed for operation. As of right now,
I've decided that a thermistor mounted in the base of the pot will work
best for monitoring coffee temperatures. Ideally it would have wide,
flexible contacts that would touch a matching set of contacts while not in
use, providing a continuous stream of telemetry to the computer.
For monitoring the level of the coffee, I was considering using an array
of CDDs, each with a constant light source. As the ball in the level
meter rises, it will obscure the light path, and cause the CDD to go low,
indicating its current location within the array. e.g:
no light------- light
=|>} | 0 | <<==
ccd ball led