Megamometer - Arduino with 8 meat probes

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Gary_G
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Megamometer - Arduino with 8 meat probes

Post by Gary_G » November 16th, 2017, 12:51 am

Here are some photos and graphs of an Arduino based data logging controller that I built in 2011.

It has 8 Maverick type meat probes, a pit probe and a thermocouple probe for measuring higher temps like the transfer tube or the drip pan. The temps are displayed on the 2x16 display, 4 probes at a time every 2 seconds. The timestamp and temperature data is saved to a SD card for review after the cook.

The charts have to be made after the cook is over using a spreadsheet app like openoffice calc. Annotations to the chart were added by a graphics editing tool.

I learned a lot building this controller and having multiple probes for the data logging. This helped document some interesting cooks and experiments to help understand how to load my smoker and get different size and shape meats done at the right time.

Also used it in an attempt to study the differences in contact, convection and radiant heat components. Radiant heat is the toughie, but I am still interested if you know how to make a radiant heat target for a thermocouple probe.

Its the radiant heat that causes the bottom racks to cook faster.

The last photo is a test where I cut up a pork loin and placed equal sized pieces on different racks to see the difference in cook times. The real eye opener was how much the transfer tube (fire) temperatures fluctuate using natural lump charcoal. Big lumps drop the fire temp and smaller ones make the fire burn hotter. See how the fan is at 100% in the first section of the cook, but the fire temp is going up and down as the gravity fed charcoal of different sizes is being consumed. Eventually the pit temp climbs to a point where the fan duty cycle % is cut to keep the chamber at 225 though.ImageImageImageImageImageImageImageImageImageImage

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Re: Megamometer - Arduino with 8 meat probes

Post by StorkQ » November 16th, 2017, 4:27 am

What a nice project. Did you use a single ADC and an analog multiplexer for probe selection?
How and where did you measure the fire temp? The usual meat probes cannot handle that heat. So probably you used a thermocouple but I don't see a plug for that. Although the first pic might show a new style thermocouple plug. :)



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Re: Megamometer - Arduino with 8 meat probes

Post by Pete Mazz » November 16th, 2017, 5:36 am

That's pretty cool !


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Re: RE: Re: Megamometer - Arduino with 8 meat probes

Post by Gary_G » November 16th, 2017, 3:25 pm

StorkQ wrote:What a nice project. Did you use a single ADC and an analog multiplexer for probe selection?
How and where did you measure the fire temp? The usual meat probes cannot handle that heat. So probably you used a thermocouple but I don't see a plug for that. Although the first pic might show a new style thermocouple plug. :)
I used an Arduino Mega because it has most of the analog and digital io, but as you can also see, I had to use an external display with buttons (DFRobot), and then layer on an Adafruit RTC shield, a proto board for probe pullup resistors(or pulldown, cant remember). I later modified the Megamometer code and added some components for driving the fan (the components all up in the air) and the ribbon cable is for the high temp thermocouple using a Max385 TC amp.

The fan and TC are connected using the speaker terminal block on the end. Here are a few close up shots the way it is today.

Several of my Maverick probes have gone bad, but I am pretty sure (and amazed) it still works.

Gary
ImageImageImageImageImage

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Re: Megamometer - Arduino with 8 meat probes

Post by Rodcrafter » November 16th, 2017, 3:28 pm

Wow that was really cool!

:-B


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Re: RE: Re: RE: Re: Megamometer - Arduino with 8 meat probes

Post by Gary_G » November 16th, 2017, 3:31 pm

Gary_G wrote:
StorkQ wrote:What a nice project. Did you use a single ADC and an analog multiplexer for probe selection?
How and where did you measure the fire temp? The usual meat probes cannot handle that heat. So probably you used a thermocouple but I don't see a plug for that. Although the first pic might show a new style thermocouple plug. :)
I used an Arduino Mega because it has most of the analog and digital io, but as you can also see, I had to use an external display with buttons (DFRobot), and then layer on an Adafruit RTC shield, a proto board for probe pullup resistors(or pulldown, cant remember). I later modified the Megamometer code and added some components for driving the fan (the components all up in the air) and the ribbon cable is for the high temp thermocouple using a Max385 TC amp.

The fan and TC are connected using the speaker terminal block on the end. Here are a few close up shots the way it is today.

Several of my Maverick probes have gone bad, but I am pretty sure (and amazed) it still works.

Gary
ImageImageImageImageImage

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Thanks ! And BTW.... here's how i like my thermocouples.... well done !Image

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Re: Megamometer - Arduino with 8 meat probes

Post by StorkQ » November 16th, 2017, 4:15 pm

Very nice, ^:)^. I figured that you were measuring in the transfertube. I like the approach a lot. For me, as non BBQ guru, measuring and logging takes a lot of guess work out of the equation. That's why I like sousvide so much. Once you know the time and temperature for a product/recipe you can't go wrong. No more under or over cooked product when entertaining a larger group.
Did you publish anything on github or so?



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Re: Megamometer - Arduino with 8 meat probes

Post by Gary_G » November 16th, 2017, 7:06 pm

StorkQ,

You mean the Megamometer code ? I may have posted it to the Arduino forum or out on a now <404> bbq forum.

I am glad to know you are interested in all the probes and logging the data.

Most of the people I shared with back in the day were cooking on smaller rigs like eggs or bullets or offsets, so nobody saw the value of 8 meat probes plus.

BTW... all this posting and review of my older projects has been really good for me. I think I figured out how to make a radiant heat measurement using a differential probe setup and a "probe shield" yet to be identified.

If I were to do it again [ Megamometer 2.0 ] it would have wireless and use i2c, preferably realtime charting using a browser, etc. ( good wintertime project, right?)

My son has been been telling me to buy something like a ESP32 or ESP8266. That would make a good Father/Son project, especially since it could help him to learn the software coding.

I will look and see if I have a copy of the old MM code that matches the pictures.

Gary

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Re: Megamometer - Arduino with 8 meat probes

Post by Big T » November 16th, 2017, 8:15 pm

Nice!! You fellas are way smarter than me when it comes to electronics.


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Re: Megamometer - Arduino with 8 meat probes

Post by Gary_G » November 17th, 2017, 12:14 am

Added the Megamometer code. It would not save as a .pde file, so it is now .txt
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Re: Megamometer - Arduino with 8 meat probes

Post by alleyrat58 » November 17th, 2017, 9:13 am

Dang that is cool as hell. I built something similar a few years ago to power multiple fans to drive my RF. I used a BBQ guru as the brains and two ATX PC power supplies as DC output to power the fans. Rig a little relay between the guru and the fans and voila! Hang as many fans as you want off a guru. I had 200 cfm going through my smoker.

I like to see the electronics guys on here.

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Re: Megamometer - Arduino with 8 meat probes

Post by Rodcrafter » November 17th, 2017, 3:52 pm

:-B :-B :-B :-B :-B


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