The Development Log


 
RJ Riememsnider said:
Will there still be support for those of us running an SSR that drives an electric element?
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Do you use the 100% for fan min/max mode, or just hook the standard output to an SSR? The former will still work because I'm leaving the min/max code in. The latter wouldn't but if you're using it I think I can make it work both ways.
 
I just plug it in and use it normally, has worked for me fine for years. I could go with min/max, would just have to go figure out how. I prefer plug-n-play :)

dave
 
D Peart said:
I just plug it in and use it normally, has worked for me fine for years. I could go with min/max, would just have to go figure out how. I prefer plug-n-play :)

dave
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If it has been used for the same thing for years then, why would you want to upgrade it to a newer board. Leave that one for the SSR and build a new one if needed for BBQ/smoker.
 
Bryan Mayland said:
Do you use the 100% for fan min/max mode, or just hook the standard output to an SSR? The former will still work because I'm leaving the min/max code in. The latter wouldn't but if you're using it I think I can make it work both ways.
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I do the latter, standard output to the SSR. It's not perfect but it works well enough for what I need.
 
John Bostwick said:
If it has been used for the same thing for years then, why would you want to upgrade it to a newer board. Leave that one for the SSR and build a new one if needed for BBQ/smoker.
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For me, it's about staying current with the software which is somewhat tied to the hardware. That said, I wasn't complaining, just inquiring about features and support. I might look at the other method as well.
 
Yeah either way it's good to bring it up so that I keep it in mind. I don't know how everyone is using their HeaterMeters, and with a lot out there I'd hate to exclude people from getting updates with new features and what not.
 
jbDP0XP.png


v4.2.2 boards are on the way to the fab. There's a bunch of major differences here
  • All high power components moved to one side, away from the measurement circuitry to reduce noise
  • The above change means that the blower/servo output is now on the left side with the power. I would have preferred to put the probes on the left and power on the right but it wouldn't fit without making the board a lot larger. Now someone can confuse the RF45 jacks, but there's a solution: don't! Or get a Model A because they're cheaper anyway.
  • Board is wider to facilitate moving the LCD 0.3" to the right. This allows it to be mounted under the HeaterMeter PCB which means the whole device is about 20% thinner. The button no longer will need a special recess to be accessed. The board is also 0.3" smaller on the other dimension so overall PCB area is a little less.
  • Space for surface mount of thermocouple components and a proper jack. This separates the pit probe from the other probes which makes it easier to remember which is the Pit and which are the Food probes.
  • Space for parts to build the buck voltage converter needed to produce variable voltage outpt rather than PWM.
 
Wow, that's a big make-over there on that board...
One question, with the thermocouple support would the pit probe jack would be changed from 2.5mm jack to a special thermocouple jack, if so then it is one or the other? That would mean a board with the thermocouple hardware would be locked into using a thermocouple for the pit probe? Any chance the software could be written so we could choose which probe functions as the pit probe, so we could still use regular probe as the pit probe at times if we like? I do use my HM on a couple different grills/smokers, I would like to build a thermocouple into my Kamado for high heat cooking but still be able to use a regular probe as pit probe on my water smoker....
 
Yeah the footprint can only be populated with one jack at a time so you'd be committed to going one way or the other. You also have to populate the pullup only if you're not using a thermocouple so it isn't just the connector it is the circuit. It is possible that I could update the software to allow you to designate another probe as the control probe.

I've also written some test code that switches the reference voltage on the ADC to 1.1V in the case the last set of readings was well below what would be 1.1V. This could increase the resolution of the thermocouple by a factor of 3 below 200C/392F. Would that be better? What's your reasoning behind using different probes for different smokers?
 
Bryan, have you decided on a TC connector yet and if so, will it mount directly to the board or will it attach via wires?
 
Yeah the Omega PCC-SMP-K. It is the only one I can find but it is only periodically in stock at Newark. I bought a few last year and they work (although the fit is pretty tight, not sure if that's just the way they are). The footprint on the PCB is to solder this directly to the HeaterMeter board. The screw hole behind the jack will almost certainly have to be employed to support the board while pushing the connector in.
 
Bryan. I was thinking I would build the thermocouple into my Kamado, but only really have the need for a thermocouple where I do high heat cooking. My other smoker(s) would all be for low and slow cooking in which regular probes work just fine. So I thought it would be nice to be able to choose which probe is the pit probe via software so I could run either thermocouple or resistive probe as the pit probe...

I was browsing through the Thermoworks catalog the other day and came across thermocouple page. This one caught my eye, Model: 113-420/425. The Industrial type K thermocouple probe, here's the spiel:

"The High Temp Industrial Probes go to very high temperatures and the stems are completely sealed against moisture. The mineral insulated sheath can be easily bent to any shape and is perfect for high temp ovens and furnaces, and are often used as long-term solutions to monitoring fireboxes and grill hoods. They can also be semi-permanently installed and will resist the weather and steam, The 78" cable is PTFE so it should be kept below 500°F, but the metal sheath section can go to 2,012°F! Available in two diameters, 1/16" or 1/8". The smaller diameter is faster and somewhat easier to bend. The larger diameter normally survives longer however, both should last for many years with modest care. Longer cables available upon request"

This seems to be pretty much what I have been looking for, wondering how you think it would work with the HM?
 
I forgot to respond to this after looking at them, sorry Ralph!

Almost none of the probes I've seen specify whether they are isolated or grounded thermocouples, which I think makes a giant difference for our application. The board that I had been testing with had real problems when you touched the probe (or probe wire, or the probe wire touched the grill and you touched the grill), on account of it creating a ground loop. The thermocouple circuit has an optional 1M grounding resistor in it, so I want to test the new board both with and without it to see what sort of difference it makes.

I have also tried with two varieties of bare thermocouples, experimenting with different ways the sensor might be permanently mounted to the grill in a way that gives a consistent reading. I think that's more of a deciding factor as well. If only the thermocouple / thermowell is going to be exposed to high temperatures, you don't have to worry too much about what the wire/sheath is made from.

In short, it is still too early to tell what's going to be a good sensor both from the mechanical and electrical perspectives.
 
OK, thanks for the reply. I'm pretty sure I still have all the parts to build another HM, so I would be in for some testing of this latest board if the prototype works out for you. This time I hope to go all the way into the thermocouple zone....
 
I too would love to put a thermocouple in my smoker (an egg) for high heat pizza cooks. I would prefer to get my Egg up tot he 800-850 range which I've been able to do with it wide open without the fan before. I use my heatermeter to temp meat indoors too and would like to be able to use the probes for those instances.

I believe this could be done as assigning the pit probe to the wireless module for regular probes and onboard for the thermocouple. Now I just need to build a wireless probe.
 
You'd still get 3x food probes, only the pit probe is replaced with the thermocouple. Not sure if you mean you need 4x food probes to temp stuff indoors, in which case yah you'd need a wireless probe (at least with the existing software).
 
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