Roaster/laptop compatibility?

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by weavdaddy »

Hi all, first post. I read somewhere about a roaster that had voltage issues traced to a faulty ground, possibly with the laptop. Is there a recommended laptop? I'm looking to buy a roaster in the next few weeks, and I really don't want to move my PC to where the roaster will be.

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#2: Post by Nunas »

First, as a retired EET, I would point out that any roaster should not have issues. While a few whirleypop type roasters are predominantly plastic and have 2-prong plugs, and others, with metal cases, have 3-prong plugs, they all must meet electrical standards. Likewise, all laptops are either floating from ground (like the whirleypop) or grounded by a 3-prong plug. There also must meet standards. That said, I am unaware of any recommended laptops to be used with roasters.

I roast in a Quest M3 (3-prong) equipped with EricS probes for ET (MET) and BT, coupled to a Mastech ms6514 dual channel temperature meter (Amprobe tmd-56/Omega hh806au are similar) by USB to a Toshiba laptop (2-prong PSU); the laptop runs Artisan. I sometimes use one of my older laptops, one of which has a 3-prong power supply cord and the other which has 2-prong. All work, but there can be issues, none of which are technically related to the laptops.

The biggest problem is related to what is called a ground loop. When designing an electronic device, we tie all the ground points to a common point, which is in turn the only place that is grounded. When the home user cobbles together several devices, multiple grounds are often present. Because the probes run on infinitesimally low voltages, noise can be injected into the circuit; this noise is interpreted by the interface as differences in readings. Overcoming this is less a matter of buying the right roaster or laptop than it is how the devices are connected. The single most important item is constant bonding. Any loose connection will generate noise that the digital thermometer or the laptop will not like. So, be sure your USB connections are clean and newish. Also, be sure that your thermoprobes are either floating (isolated from the roaster) or firmly bonded. A loose probe will cause a problem. In my set-up, my ET probe runs through a drilled out screw. The fit is sloppy and if I wiggle the probe even a bit, I can get some really garbage readings. EricS recommends that the probe be fixed with cement, as I recall. That would be good, or maybe wrapping some metal foil around the probe to provide a good bond would also do if you want the probe to be removable. If you do have issues related to ground loops and your laptop has a decent battery, you might be able to overcome the problem by not using the PSU for the laptop.

Perhaps EricS will jump in here, as he's the guru of this stuff.

BTW, you did not mention which roaster you're buying. That might be good to know as there are a ton of guys (and a few gals) on this site who may have encountered and solved issues with your proposed roaster.


#3: Post by weavdaddy »

Thanks for the reply Nunas. I am looking at the 1kg gas roaster from Mill City, as it has glowing reviews ( ... e-roaster/ see Michael Goble's entry), is priced far lower than what I would expect, and has all the features I think I need. I am open to alternative suggestions but for the capacity I haven't found anything better.

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#4: Post by Nunas »

Lovely roaster! Colour me jealous. I doubt you'll have problems, as the roaster was designed from the get-go to work with a computer. Most of us that have had a few problems have adapted our roasters to work with our computers. Enjoy!


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#5: Post by millcityroasters »

We've had a couple of guys report feedback on their Phidget thermocouple readings on Mac laptops when charging. On battery they work fine. When charging they get spikes on their Artisan plots.

Of the hundreds of guys using a Phidget for datalogging, this has come up exactly 4 times and never on a new Mac. I suspect it's one particular model, but it's been infrequent enough that I haven't made any attempt to verify this.

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#6: Post by turtle »

I use my older X-300 lenovo with both of my roasters without any uses, interfacing with a TCM-56 meter and TC4C and USB connections to the laptop.

When getting a laptop consider size. The x-300 has a very small footprint.

Mick - Drinking in life one cup at a time
I'd rather be roasting coffee


#7: Post by jgbnm »

I'm using a 2 year old Macbook Pro with my TJ-067 and Artisan. Works great. I run it off battery simply because I don't want to drag my power cord back and forth between the house and the roaster and I don't have any issues with battery life. I've never actually tried it with my MAC plugged in.

My TJ-067 has been a great choice.
The more I learn, the more I realize just how much there is to learn.


#8: Post by edtbjon »

I use a 10 year old Acer laptop running a lightweight Linux (Lubuntu). It took some work to find and install all the drivers needed (for my Phidget 1048), but no rocket science needed. (I still got a problem with not getting Artisan connecting with the Phidget as a normal user. Have to run it with "sudo"...).
Anyhow, Artisan as such doesn't need much in terms of computer power. At least with the above setup on an old Celeron processor, Artisan runs smoothly. (I tried the same computer with a normal/new Ubuntu dist. and that was absolutely terribe. Everything slow as molasses floating uphill.)

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#9: Post by JK »

I have built many PC over the last decade..
IMHO buy a used laptop off eBay for a good reseller of used corporate laptops..
Many come with 30-90 warranty's

I bought 3-4 years ago a Leveno T410 Thinkpad for around $200 I added a SSD hard drive and other than it weights a ton compared to my $1,000 Asus Zenbook I bought new I'm happy using either other than the huge price difference..
Both Windows 10 compactable..

Look for a T420, T430 or T510, T520 even a X models with a i5 processor, they are running around $200..
The T410 is getting old but still almost as fast as my Zenbook i7
I'm on a Mission from God!


#10: Post by fu11c17y »

I have the same result with 2 different laptops: Macbook Air 2010, and a late model Acer Chromebook running Chronos Ubuntu.
Plugged in, spikes everywhere on graph. Unplugged running on battery, no problem.