Jim has announced the availability of the new HTC Hottop
interface board. Plugged into the TC4C and a few added components, you end up with a computer-controlled home roaster ("just add computer). Owner's manual to follow soon we hope. It's in the works.
In the meantime, I thought I would post some specific info on my installation...
Here is a photo of the installation I did in my KN-8828B-2K. As you can see (hopefully) there is plenty of room to mount the two boards.
1 - HTC board. A custom-designed board to create an interface and control system
2 - The TC4C board provides USB I/O and Thermocouple connection point.
These two boards are powered through the USB connection. Plug in the USB cable and control functions are through the USB. Unplug the USB and the Hottop operates as intended by the factory through the Hottop control panel as if the HTC system were not installed.
The aluminum shelf upon which they are mounted is attached through the side panel. I drilled and tapped two holes in the bracket which is pop-riveted to the fabricated aluminum shelf.
3 - Thermocouple leads.
4 - USB cable. I later removed that cable and used a "Cables-To-Go" 28071 male to panel mount cable. I installed it in the rear cover and it is the only external sign that the roaster has been modified:
5 - The two Hottop ribbon cablesBasically, you have three tasks for physical installation:
A - Install two K thermocouples (bean temperature and environmental temperature). These vary widely. I started with bayonet mounted from e-bay, but the thermocouples themselves were of low quyality. I kept the mounting but just used the leads and twisted the wire ends. These are a lot tougher than the fine-wire exposed thermocouples, faster responding than stainless covered thermocouples, yet still seem accurate enough. I inserted them through a short piece of silicone tubing so they are easy to remove for maintenance and replacement. The mounts are shown here, epoxied in place:
B - Mount the boards
C - Wiring.
i -connecting the thermocouples leads
To run the thermocouple leads I enlarged the existing opening in the frame and routed the leads under the main board. This brought them up in the rear of the roaster (as seen in thr first photo). This makes them ore accessible when connecting them. The two clamps seen here are 1/4" pipe clamps modified to hold the leads. I insulated them using insulation covering from an electrical extension with the internals removed:
ii - connecting the two ribbon cables (one from the control panel to the HTC and one from the HTC to the Hottop Main Board
iii - connecting a USB cable to go from the TC4C to the computer.
The two boards come with a few other connecting wires, and there is an LED on a long lead that is illuminated anytime the heating element is sent power. This is optional and works well as a troubleshooting device.
What you end up with is a control system that gives a repeatability and control level that is astounding.
I have only used it with RoastLogger
so cannot comment on functioning with Artisan. Not brave enough to deal with the reprogramming at this point. When things settle down I will contact Jim and Tom and see about that. The programming instructions I had previously seen were unclear, and I am too busy to deal with the possibility of screwing up my control system at this time.
Being able to visually see (on a graph) what the roaster is doing in real time along with the control that this system (HTC+TC4C & RoastLogger) is addicting. I am still fine tuning (and probably always will be), but RoastLogger lets you load a previous roast's data into the graph and then you can roast "over" that for comparison as seen here (previous roast in pastel colors, current roast in dark colors):
It allows you to be sure a roast is duplicated (like when you change air filters, put in a new heating element, or are roasting somewhere with a different line voltage), and it allows you to verify programming changes you have made. RL also gives you the opportunity to save the programming and later load it, so you can have various roasting parameters for different coffees, different weather conditions, or different brewing methods, and the like.