by Randy Glass - Copyright 2013 - All rights reserved
E-mail me at firstname.lastname@example.org
As has been widely discussed, Jim G. of MLG Prperties is not currently able to supply us with his HTC+TC4C circuit boards which act as an interface between Hottop coffee roasters, and a computer running a control and logging application, which in my case was RoastLogger by GreenBean (aka Tom). Jim has stated that he would likely be able to supply his boards again in about 4 months or so (Jim's estimate if I correctly recall), so Tom, the author of RoastLogger as well as having been a key member in the development of the HTC board, stepped in and designed his own board to fill the need for now.
photo Courtesy of "GreenBean"
Tom calls his solution the RL-HT-CTRL (RoastLogger Hottop Control). Among its benefits are:
Above you see one of the Action panels. This one is "Action at T1." Simply, the first line there tells RoastLogger that when the T1 temperature reaches 248 (Fahrenheit in this case) to set the heater element to 90% power and the fan speed to 30%. They do not have to be entered in order and you can enter up to ten, although I have found that three do an excellent job. You can even save various "Actions" in a file so that you could create any number of them for different roasts; for different origins, for different brewing methods, for decaf, etc.
Here is a portion of a graph of two roasts. Both were done using the same set of "actions." The data in the inset box shows the First Crack Start (FCs), First Crack End (FCe) Second Crack Start (SCs) and the End of roast. These points are marked during the roast by the user by pressing an on-screen button. In each cell of data you have the time (number of minutes and seconds since beans were added) and the "T1" temperature which it from the bean sensor. Roast Logger allows you to load a previous roast as a "template" onto the graph before beginning the roast. That is shown by the thinner, lighter-colored blue and red lines. The current roast, logged onto the same graph in real time, is represented by the thicker darker lines (the thickness of the current roast's lines can be modified as an option). It is plain to see that with no input from the user, these two roasts progressed so identically that differences are difficult to find. If nothing else, this graph shows the remarkable potential in the Hottop Roaster which RoastLogger unlocks.
The chart above was done using the last roast's log from the chart above and making just one change to one parameter in the "Actions" file. One of the "Action" choices you can enter is to set the heater power and fan speed at any given "T1" temperature. I have used three of the ten available "Actions at T1" programmed. For the template above it was "at 350F set the heat to 55%, and set the fan to 50%. I changed that by lowering the temperature for that Action to 340. This left the 2:00 "dwell" between the end of first and the beginning of second unchanged, but it delayed the onset of first by one minute. That was my goal for this roast; to lengthen the total time just a bit.
We can debate my profile ad nauseum, but that is not the point of this portion of my review. The two graphs presented above were placed for two reasons:
1- To show the consistency that the Hottop is capable of producing
2- To show that with the proper interface and control system, it is possible to get very precise control over this roaster, and do so with a repeatability that would be difficult, if not impossible manually.
A big part of that comes from Roastlogger being able to control both the fan and heating element in 5% steps (the factory Hottop control is heat in 10% increments and the fan in 25% increments).
The control of teh Hottop as mentioned above is available using RoastLogger and either the RL-HT-CTRL board or the HTC+TC4C. Tom is willing to build a small number of RL-HT-CTRL boards to fill the gap until the HTC and TC4C are back in production and hopes to convince JimG to move the development of the TC4C towards true USB communication in future.
The rest of what you need to know is available HERE on the RoastLogger website. These boards will be available in short supply unless things change in the future.