HomeRoast Digest


Topic: PID on IR2 (6 msgs / 183 lines)
1) From: sci
Has anybody ever done a PID on an IR2?
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2) From: Allon Stern
On Apr 21, 2008, at 12:43 PM, sci wrote:
<Snip>
Not yet. Planning to.
current state of disassembly:http://www.radioactive.org/iRoast2%20Teardown/Photos.htmlStill need to suss out the signalling to the control board.
-
allon
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3) From: sci
Allon,
THanks for the update. I hope it works. I'd love to do it someday, but I
don't have the electronics background to actually do it for the first time
(i.e.,suss it out). I think I could duplicate what somebody else did, using
their instructions. I really like the IR2 and it does roasts many beans
superbly, but it is a limited platform. A PID, as I understand it, could
fix  many of its quirks and make it an outstanding fluid-bed roaster. So,
keep on hacking.
Ivan
Date: Tue, 22 Apr 2008 18:31:13 -0400
From: Allon Stern 
Subject: Re: [Homeroast] PID on IR2
To: homeroast
Message-ID: 
Content-Type: text/plain; charset-ASCII; format=flowed
On Apr 21, 2008, at 12:43 PM, sci wrote:
<Snip>
Not yet. Planning to.
current state of disassembly:http://www.radioactive.org/iRoast2%20Teardown/Photos.htmlStill need to suss out the signalling to the control board.
-
allon
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4) From: Tom & Maria - Sweet Maria's Coffee
<Snip>
okay Allon - you deserve just a little ribbing. i can take apart an 
iRoast too. In fact, I am really, really good at taking things apart. 
I don't do it quite as neatly as you do. Usually it ends up in little 
neat piles, and of course I know where everything is ... for about a 
week. but about a month later I have no idea what is what, and I 
probably bumped the bench a few times, and what's this spring and 
this crew on the floor? and ... well, that's the end of that. I am 
throwing down the proverbial gauntlet. I have never seen anyone PID 
an iRoast2. I can't image how you would override the board - or would 
it mean circumventing the board and simply using a constant fan speed 
and PID controlled heating element? would love to see what you can 
make of it ... keep us informed
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
                      http://www.sweetmarias.com                Thompson Owen george_at_sweetmarias.com
     Sweet Maria's Coffee - 1115 21st Street, Oakland, CA 94607 - USA
             phone/fax: 888 876 5917 - tom_at_sweetmarias.com
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5) From: bv welch
Greetings,
Sounds like a fun project.  I've never seen the inside of the iRoast2.  But
from your photo, it looks like a nice, 120 volt "universal" fan motor.
How does the construction of the iRoast2 compare, say, to the early WearEver
Pumper and original WB Poppery? Now those are some fine, heavy-duty
machines.  Other than the brittle ceramic housing for the heater, they seem
perfect.
What would the advantage be for a modded iRoast2, over the Pumper or P1?
Or for that matter, over the original iRoast2?
I'm interested in such a project, but would like to know the
advantages/reasons.
Meanwhile, even though I've had success with my home-made PID roaster, I've
set it aside until I learn more how to manually roast. :-)
Bill
On Wed, Apr 23, 2008 at 3:11 PM, Tom & Maria - Sweet Maria's Coffee <
sweetmarias> wrote:
<Snip>
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6) From: Allon Stern
On Apr 23, 2008, at 4:11 PM, Tom & Maria - Sweet Maria's Coffee wrote:
<Snip>
I'm planning to use the original relay board, with my own control  
board. But first I need to work out the signalling between the two -  
at first I thought it would be simple, and it probably is, but not as  
simple as I first thought. The fan appears to be controlled by an SCR  
or TRIAC, which requires a pulse train tied to the 60Hz of the input  
line. That means to control the fan speed fully variably, I can just  
change the phase of the pulses. I should probably rig a full-speed  
bypass on the fan, run the heater coil wire through an inductive  
ammeter probe, and play with the other inputs, which are almost  
certainly just straight relays. I haven't had the time yet to draw  
the circuit diagram - having three kids 1, 3, and 5 takes up most of  
my spare time.
Oh yeah, the board I plan to use is the Arduino Diecimila -http://
www.sparkfun.com/commerce/product_info.php?products_idf6
I can use the analog inputs for a thermocouple probe in the bean  
mass, and the digital I/Os to control the relays. Oh, and another  
analog input to figure the phase of the input A/C and clock the fan  
control. The PID algorithm will be implemented on the ATMega cpu.
The goal is not to have a standalone roaster - I plan to drive the  
control board from a host computer. The host computer will keep time,  
watch the temperature, and change the setpoint of the PID to  
implement the programmed profile. It will also store logs of the  
roasting sessions.
On Apr 23, 2008, at 4:31 PM, bv welch wrote:
<Snip>
Why pid it? Because the current controller is crap. It has no real  
idea what the temperature is, so it runs open loop most of the time.  
Also, I want the ability to load profiles from a database, and store  
roasting logs in the same database.  The goal is not just to roast to  
a given profile, but rather to marry the roasting profile into a  
database which stores more than just profiles. Oh yeah, you can't  
meaningfully change the program of an iRoast once it is going. You  
have little manual control.
<Snip>
Yup.
<Snip>
Dunno. The heater/fan assembly seems pretty nicely built. I happened  
to come by a spare iRoast2 so I'm using it as a model for my  
experiments.
<Snip>
Excellent. The first step here is to do manual control of the  
roaster. Then I can do manual control with logging, so I can capture  
what I did, graph it, tweak it, turn it into a profile.
The controller I build using the Arduino could be adapted to work  
with a poppery, pumper, or totally homebuilt roaster. The idea is to  
focus on the control electronics, not the implementation of the heat/ 
fan.
-
allon
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