|
Monitoring Temperature
|
| Unta |
Posted on 03/29/2010 18:49
|
Administrator
Posts: 224
Joined: 26.01.10
|
What is everyone out there in air roaster land using to monitor heat. Also where are you monitoring the temps...I am using Grill thermometers, 8 dollar dial versions, bought at the local hardware depot.. I'm monitoring temp at the end of the reddi heater, just before the roasting chamber, the supposed area where beans are settled in the RC..(im skeptical of that one) and just before it enters my chaffee collection/ exhaust removal chamber.. my temps generally are generally as follows for a 4kilo roast, all in Degrees F..900, 625-650, chamber temps usually top out around 500-550. and pre exhaust temps usually start at 100 and follow in proportion to the RC temp topping out at 200 or so.. ..
Sean Harrington
educate. |
| |
|
|
| endlesscycles |
Posted on 03/29/2010 19:59
|
1/2 Pounder
Posts: 239
Joined: 11.04.09
|
The cheap units for sale at Sweet Marias. They work okay. I crave something a bit more awesome and will drop the coin as soon as I know what that is and can
-Marshall Hance
Asheville, NC |
| |
|
|
| seedlings |
Posted on 03/29/2010 20:28
|
Super Admin
Posts: 3056
Joined: 27.06.07
|
I've used the TCs included with inexpensive multimeters ($30), but those do not like to be agitated. Currently I'm still using: http://homeroaste...#post_8841
I'll worry about new TCs whenever I get around to building a roaster.
CHAD
"You know, I think that horse is getting deader." |
| |
|
|
| RoasterRob |
Posted on 03/30/2010 02:38
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
Have been using a long stork digital thermometer. Readout is to to the nearest tenth of a degree C up till 200C then it only displays to the nearest degree. JMO you want the display to display to the nearest tenth deg so you can see that the roast is progressing, otherwise if the roast stalls you don't realize it soon enough.
Some time ago I had a friend build a 2 TC display unit that would also give a readout with the delta/T of the bean temp. It wasn't stable enough and didn't work as planned.
I discussed it online some years ago, shortly after that I noticed people discussing temp and delta T on coffee snobs and HB. Don't know if I was the first to bring it to peoples attention but I never saw it mentioned till I brought it up online.
CoffeeSnobs.com.au have a multimeter unit and software that data logs, displays temp, graph and delta/T on a laptop via USB.
The delta/T is basically how I roast.
I manually log the temp every 30 secs. If the increase was 7deg C from 4 to 4.5 min then I will turn the air flow down a little so that the D/T is 7C from 4.5 to 5 etc. If the D/T was 9 between 4 and 4.5 (and the bean mass temp is over 140ish C) I will leave the air flow as is the D/T from 4.5 to 5 min will be close to 7 then I will start to decrease the airflow to stay at a D/T of 7 till into the 190s C.
What i really want is an electronic variable resistor (controlled by a PIC or similar) to replace the manual VR in my dimmer. Have the Pic change the resistance based on the bean mass temp.
Rob
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| Unta |
Posted on 03/30/2010 19:04
|
Administrator
Posts: 224
Joined: 26.01.10
|
where in the chamber are you taking bean mass temps.. the beans appear to be a very active in the RC from the short videos that I've watched.. sean
Sean Harrington
educate. |
| |
|
|
| RoasterRob |
Posted on 03/30/2010 23:20
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
See diagram this page
http://www.homeroaster.com/rob.html
What you don't see in the video is the larger mass of beans that the spout of beans pour onto.
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| JimG |
Posted on 04/01/2010 06:19
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
RoasterRob wrote:Some time ago I had a friend build a 2 TC display unit that would also give a readout with the delta/T of the bean temp. It wasn't stable enough and didn't work as planned.
The little gizmo I built for a delta/T readout is working pretty well for me. More details here:
http://www.home-b...12174.html
Jim
Edited by JimG on 04/01/2010 06:20 |
| |
|
|
| RoasterRob |
Posted on 04/01/2010 21:11
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
Hi Jim
The circuits don't look too difficult to build. What options are there for displaying it? Is there a simple way to display via a computer.
Or are you also building these units up and selling them.
Next question- any thoughts on a simple circuit to control an electronic variable resistor?
cheers
Rob
Edited by RoasterRob on 04/01/2010 21:12
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| JimG |
Posted on 04/02/2010 17:41
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
RoasterRob wrote:
The circuits don't look too difficult to build. What options are there for displaying it? Is there a simple way to display via a computer.
Hi, Rob -
So far, I've only used a multimeter to display the output.
It would probably be fairly(?) simple to amplify my circuit's output a little, then connect it to the ADC on a basic Arduino board. Once done, displaying the output on a computer via USB link should be easy.
RoasterRob wrote:Or are you also building these units up and selling them.
No, not selling them, at least not for profit. I have a couple of extra unpopulated PCB's that cost me around $15 ea from BatchPCB, which I would sell at cost. Or anyone can order direct from BatchPCB for that same price.
RoasterRob wrote:Next question- any thoughts on a simple circuit to control an electronic variable resistor?
If you are looking to be able to electronically control your heater output, then a phase angle control SSR (i.e. a fancy dimmer switch) would be the way to go, I think. By electronically controlling the input signal from around 2V to 10V, the output is varied from around 0% to 100% by chopping up the sine wave form.
Jim
Edited by JimG on 04/02/2010 17:43 |
| |
|
|
| JimG |
Posted on 04/02/2010 18:52
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
RoasterRob wrote:Next question- any thoughts on a simple circuit to control an electronic variable resistor?
I think I now understand that you are looking for a way to control fan output, not heater output. And I also think I understand that you would like the fan output to be reduced as the bean mass temperature rises?
If I've got that right, then a fairly simple PID setup could work. You would configure the PID for proportional control only (I = D = 0). Use a PID that can output a 4-20mA current.
You would feed the thermocouple signal from your roast chamber into the PID. The 4-20mA output from the PID would be fed through a 500 ohm resistor placed across the input terminals of a phase angle control SSR.
Its possible that the fan motor will not behave well on the output end of a phase angle controller. But I suspect it will be OK since you will probably be operating in a range where the phase angle stays pretty close to zero.
Off the top of my head, I would expect that a Delta DTB4824CR or DTB4824CV PID controller (less than $80US) would work. A Watlow 96 controller with F hardware on OT1 would be a far better choice, but more pricey unless you can find one used. A Crydom 10PCV2425 solid state relay would be suitable, I think.
You would need to experiment a little to determine the relationship between fan speed and input voltage to the SSR. But once you've figured out how many DC volts you need going into the SSR to give the fan speeds you want at the two limits, you'll be able to set up the PID to duplicate this on every roast.
Jim |
| |
|
|
| RoasterRob |
Posted on 04/03/2010 04:41
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
JimG wrote:
RoasterRob wrote:Next question- any thoughts on a simple circuit to control an electronic variable resistor?
I think I now understand that you are looking for a way to control fan output, not heater output. And I also think I understand that you would like the fan output to be reduced as the bean mass temperature rises?
If I've got that right, then a fairly simple PID setup could work. You would configure the PID for proportional control only (I = D = 0). Use a PID that can output a 4-20mA current.
You would feed the thermocouple signal from your roast chamber into the PID. The 4-20mA output from the PID would be fed through a 500 ohm resistor placed across the input terminals of a phase angle control SSR.
Its possible that the fan motor will not behave well on the output end of a phase angle controller. But I suspect it will be OK since you will probably be operating in a range where the phase angle stays pretty close to zero.
Off the top of my head, I would expect that a Delta DTB4824CR or DTB4824CV PID controller (less than $80US) would work. A Watlow 96 controller with F hardware on OT1 would be a far better choice, but more pricey unless you can find one used. A Crydom 10PCV2425 solid state relay would be suitable, I think.
You would need to experiment a little to determine the relationship between fan speed and input voltage to the SSR. But once you've figured out how many DC volts you need going into the SSR to give the fan speeds you want at the two limits, you'll be able to set up the PID to duplicate this on every roast.
Jim
Yup for controlling the blower. I really need to start studying up PIDs and SSRs.
The blower (presently) operates over a range from 90% to about 40% (best guess) I was keen to stick with the basic triac dimmer because I know it works. The circuit for the dimmer is this one http://www.epanor...ml#1kw230v
The Triacs I use are BTA12 600B. From what little I can work out Traics don't operate on an ingate voltage range of 2 to 10V. Apparently BTA/BTB type are recommended for inductive loads. Not sure how inductive a universal motor is.
As for PIDs I was given a Honeywell DC4000 5G don't know if it of any use for this.
Anymore information you have time to throw at this would be much appreciated.
cheers
Rob
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| bvwelch |
Posted on 04/03/2010 06:02
|
1 1/2 Pounder
Posts: 892
Joined: 27.12.07
|
Hi Rob,
I'm confused - you seem to have great roasters and good control over your fan already. Can you explain what you're looking for with a new/different/improved circuit for controlling fan speed? |
| |
|
|
| JimG |
Posted on 04/03/2010 13:32
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
Rob -
Your triac dimmer works on the same principle as the SSR I've got in mind. I believe the phase angle of your dimmer is controlled by the P1/P2-R1-R2-C3 time constant. So that makes me think what I've outlined using the phase angle SSR should also work.
Would need to do a little more investigation to see if the Crydom 10PCV series can handle the inductive loads, but I suspect this problem could be overcome (if it exists at all).
Once you have the 10PCV (or similar) SSR, you could test the concept very easily by manually varying the input voltage to the SSR. If you don't have an easy way to vary the DC voltage, you could probably just use a 9V battery and a few resistors.
I'm not familiar with Honeywell PID's in general, so I can't tell you if that unit can output a 4-20mA signal. I am very familiar with the Watlow line, though, and would be happy to help you source something.
Jim |
| |
|
|
| JimG |
Posted on 04/03/2010 14:10
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
RoasterRob wrote:
The circuit for the dimmer is this one http://www.epanor...ml#1kw230v
The Triacs I use are BTA12 600B. From what little I can work out Traics don't operate on an ingate voltage range of 2 to 10V. Apparently BTA/BTB type are recommended for inductive loads. Not sure how inductive a universal motor is.
Another idea is contained further down in the document you linked. If you already have the dimmer circuit built and working, then perhaps you could substitute a photoresistor (LDR) in place of the potentiometer you are now using (you may have to adjust some other resistors and/or capacitors, too).
The 4-20mA output signal from the PID would be run through an LED. The varying LED brightness would control the resistance of the LDR. This is kind of a nice solution since it wouldn't require you to fiddle around with the triac arrangement that is now working.
Jim |
| |
|
|
| RoasterRob |
Posted on 04/04/2010 05:08
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
bvwelch wrote:
Hi Rob,
I'm confused - you seem to have great roasters and good control over your fan already. Can you explain what you're looking for with a new/different/improved circuit for controlling fan speed?
Hi Bill
True it does have good control. I am however looking to partially automate it. By having a PID or similar control the fan speed and an accurate temperature readout with a stable delta/T, then the only thing to adjust is the gas. I do have bigger plans for this down the track. 
Rob
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| RoasterRob |
Posted on 04/04/2010 05:22
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
JimG wrote:
Rob -
Your triac dimmer works on the same principle as the SSR I've got in mind. I believe the phase angle of your dimmer is controlled by the P1/P2-R1-R2-C3 time constant. So that makes me think what I've outlined using the phase angle SSR should also work.
Would need to do a little more investigation to see if the Crydom 10PCV series can handle the inductive loads, but I suspect this problem could be overcome (if it exists at all).
Once you have the 10PCV (or similar) SSR, you could test the concept very easily by manually varying the input voltage to the SSR. If you don't have an easy way to vary the DC voltage, you could probably just use a 9V battery and a few resistors.
I'm not familiar with Honeywell PID's in general, so I can't tell you if that unit can output a 4-20mA signal. I am very familiar with the Watlow line, though, and would be happy to help you source something.
Jim
The Honeywell unit has diagrams showing 4~20mA output. Inputs for T/C, RTD, V,mV. 120V or 240V supply. Relays, comm (rs422) and more. Its been in a box in the garage for some 5+years. Somewhere I have a manual for it. Last time I looked at it I couldn't make sense of it. Might be time to hook up power to it and start pushing some buttons.
Also time to hunt down a PA SSR locally.
Thanks for all your input Jim.
Rob
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| Unta |
Posted on 04/04/2010 07:17
|
Administrator
Posts: 224
Joined: 26.01.10
|
JIM OR ROB,
Do either of you have line drawings of these different scenarios you are discussing. I'm following most of what your discussing theoretically, though i get lost in a few of the specific components.. a recommended website or book would be awesome also..im sure some of us that havent thought in great detail about these automating processes might be able to get out of this thread with some great direction.Awesome discussion BTW.. best regards..Sean
Sean Harrington
educate. |
| |
|
|
| endlesscycles |
Posted on 04/04/2010 11:24
|
1/2 Pounder
Posts: 239
Joined: 11.04.09
|
RoasterRob wrote:
Hi Bill
True it does have good control. I am however looking to partially automate it. By having a PID or similar control the fan speed and an accurate temperature readout with a stable delta/T, then the only thing to adjust is the gas. I do have bigger plans for this down the track.
Rob
Stable environmental temp and simply dial in the dT?
That would rule. No more etch a sketch...simply dial-a-roast!
-Marshall Hance
Asheville, NC |
| |
|
|
| farmroast |
Posted on 04/04/2010 12:30
|
1/2 Pounder
Posts: 153
Joined: 20.12.06
|
I tend to be pretty reserve when it comes to automation. It makes sense in a commercial situation where you might be roasting the same beans same load same level on the same day. But little variables can change the timings of temp adjustments and cause significant differences in the cup. The starting temp. of the roaster too can change the profile and times for the rest of the roast. I'm a huge advocate for all the monitoring technology possible. The rate of BT rise meter system that JimG made for me has been great. It allows me to see momentum changes as soon as they begin to happen and limits drastic corrections. I wanted the stand alone meter vs. having it in a computer programs as I no longer data log every roast. I found past data to need so many considerations that it became overly complicated. I know what most beans are apt to do and just make adjustments on the fly reacting to what the beans are asking for.
Ed B.
DreamRoast 1kg roaster, Major, Olympia Cremina, Technivorm 741 http://coffee-roa...gspot.com/ |
| |
|
|
| JimG |
Posted on 04/04/2010 12:30
|
1/2 Pounder
Posts: 106
Joined: 23.10.08
|
Unta wrote:
JIM OR ROB,
Do either of you have line drawings of these different scenarios you are discussing. I'm following most of what your discussing theoretically, though i get lost in a few of the specific components.. a recommended website or book would be awesome also..im sure some of us that havent thought in great detail about these automating processes might be able to get out of this thread with some great direction.Awesome discussion BTW.. best regards..Sean
Hi, Sean -
Unfortunately, I do not have any diagrams. But if using the PID/SSR option (instead of a triac dimmer circuit that is built-up from components), the diagram would look very simple.
Mains power to blower motor goes through the output terminals (1 and 2) of the SSR, just like a simple light switch.
Output from PID (assuming 4-20mA) goes to the input terminals of the SSR (3 and 4). A nominal 500 ohm resistor is also connected across the input terminals. This converts the current to a voltage in the range of 2V to 10V.
For simple fan speed control, the PID is programmed to output 4mA at whatever temperature you choose to correspond with minimum fan output (say Tmax). It is also programmed to output 20mA at the temperature at which you'd like to start slowing down the fan (say Tmin).
Then you use simple proportional control with P = Tmax - Tmin, and I = D = 0. Set up this way, the PID will linearly vary the output between these two temperature limits. FWIW, I used to have my Hottop set up this way (only in reverse), but now I manually vary the fan speed based on the amount of smoke.
To fine tune performance, there are lots of little tweaks. You can use something other than a 500 ohm resistor at the SSR, or you can specify upper and lower output level limits for the PID, etc. But the basic idea remains the same.
Does this help?
Jim |
| |
|
|
| Unta |
Posted on 04/04/2010 17:36
|
Administrator
Posts: 224
Joined: 26.01.10
|
very much.. thanks.
Sean Harrington
educate. |
| |
|
|
| RoasterRob |
Posted on 04/04/2010 21:52
|
1/2 Pounder
Posts: 146
Joined: 03.03.07
|
Found the manual (100pages A4) for the Honeywell PID unit. copywright 1985 this thing is about 6"x4"x10".
Reading thru, as it is the 5G model it is current proportional. My friend Paul (lever espresso rebuilder) said he had a PID and SSR spare so between my honeywell unit and his gear I should be able to put something together.
Rob
VBM Minimax 2gp,SJ Maz, FB 2.3kg HM roaster |
| |
|
|
| NectaroftheGods |
Posted on 07/22/2010 10:29
|
Newbie
Posts: 2
Joined: 21.07.10
|
I'm new to the site and was wondering if anyone ever bought the TC Digital Thermometer from SM http://www.sweetm...ouple.html? I'm contemplating on either that or the CDN Digital Thermometer with probe: http://www.bedbat...45141P.JPG
My use is to monitor heat in my Behmor and also with a future hot air bed roaster.
Thoughts?
Nectar |
| |
|
|
| bbqbeans |
Posted on 07/22/2010 11:22
|
Newbie
Posts: 3
Joined: 27.09.09
|
Welcome to the site! I post infrequently but visit often! If you're looking at the digital thermometer with k-type thermocouple, here's the exact same one for less$!
http://www.web-tronics.com/digtherwkpro.html
I have this one for my RK setup and it works well!
Mark
Mark O.
RK Drum roaster
markosbeans.com |
| |
|
|
| NectaroftheGods |
Posted on 07/22/2010 11:55
|
Newbie
Posts: 2
Joined: 21.07.10
|
Thanks Mark, that was a good find; it's always good to save a few bucks.
Nectar |
| |
|
thanks for your patience and support!
