New to the Heatermeter and I have a few questions.


 
A

Aristotle Allen

New member
I'm finally taking the plunge on the heatermeter. I have good deal of experience with microcontrollers Arduinos, RPis, though I really spend more of my time now building guitar pedals, I really love the analog stuff, and I do play. So I bought the 4.2.4 board, and stuffed it will all the parts I have on hand. I've gotten pretty far. I also had a few RPis laying around unloved, so one is being used here. So thats me, and where I'm at. How about a few questions?

There are a lot of configurations available. I think want to go for 3 probes, and one thermocouple, but is there really any advantage over using 4 probes? Seems like the surface mount parts are going to be a pain, and I can use a probe for a grill temp sensor anyway right?

Ambient temp? Where do I put the thermistor? Also, does this mean I'm giving up a probe? If so I'll skip it, but if its free to add, I would like to add it.. I just don't see where.

ICSP and FTDI connections. Any reason to solder these up? I have an ICSP programmer, and an FTDI to USB adapter, but I don't think I'll need them, the software seems pretty mature.

Oh and lastly the 4 way "button" the part on the heater meter BOM is obsolete, anyone have a spare, or can recommend a replacement part #?

Anyway, just pulling parts from the bin... only spent a few bucks for the board I've made it this far.

https://goo.gl/photos/XK1TQHvk4Pu33D4KA

Thanks in advance for the feedback. I'm pretty pumped about having a proper controller for my 22.5" WSM. I want to be sure what I need before I start ordering... $5 to ship a 3 cent part... you know how that goes.
 
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Let me try to hit on all your points.

As for the probes and TC, the main advantages of having a TC pit probe is you can get TC's that can handle much more heat, mine can stand over 2000F! So this makes them good for high heat cooking in a Kamado, which a lot of us do. I melted a LOT of standard "high heat" probes before I went TC, haven't melted a pit probe in over a year now that I have gone TC. Also, my TC is completely water/steam proof. TC's in general are much more durable than standard probes, which is the second advantage. And they are often cheaper as well. But yes, you can use a standard probe for a pit probe, but this is best suited for smokers only that will not be doing any high heat cooking... and don't get it wet, trust me....

The ambient temp thermistor can be wired whatever way you want. The standard config is to solder it across the gnd and the switched leg on the last food probe (the switched leg is the middle leg, the one that is offset a bit). Done this way the ambient temp thermistor will register by default, but if you plug a probe into the jack the switch will open and the probe will function instead, so you don't lose a probe. (you will have to change the probe config in the software if you do that though). You can also wire the thermistor across the tip and sleeve of a mono 2.5mm jack and plug the ambient temp thermistor in from outside the HM where it will get a more accurate reading.

You don't need to worry about the ICSP and FTDI headers, one is for a RF module for a wireless probe and the other is for wiring probe jacks that are off the main HM board.

I posted yesterday about the 4-way button in a thread where someone had a bad one.... They are still available from one major supplier that has over 1000 of them and only wants a buck each, but I think the shipping will get you... There is also a seller on ebay that has them listed for $3 including shipping.

Hope that was helpful...
 
@Ralph - thanks for the feedback. I'll be using this on my WSM, so I think a thermocouple is not required. I did get a "high temp" pit probe though based on your feedback. My WSM has never hit 500 deg, so I think I'll be more than good there with a 700 deg pit probe. If I make a second one to control a grill though, I'll make sure to use the thermocouple.

I also think I was able to get all my parts from mouser, so if it all goes well with my order, I'll pass on some additonal part numbers.

@Jas E - I'm a big fan of SMD, but I'm not totally on board with the design of the 5.0 board. The pitch size of that AD849X already makes me cringe a little, but at least with the 4.2.4 board the SMD parts are on one side, with a stencil and a toaster oven you could reflow it very easily. I have a reflowster for just that purpose. http://reflowster.com/ (No affiliation) I've made many a solder mask from cola cans... it works great. I think you have to be really careful with SMD though. Kits go from DIYer to enthusiast very quickly, and you lose your already niche market. I've been people like Limor over at Adafruit, Josh at JMK, and Brian at MadBean. I think it is great you are pushing the design forward, I just hope through hole stays an option too. Getting very off topic here... thanks for pointing it out.
 
I'm aware of the additional skill required to do SMD soldering. It comes easy for me to solder it all by hand, but I do remember years ago when I incinerated my first SMD chip. Lol. I believe I assessed my target audience correctly as you have plenty of experience with solder masks and own a reflow oven. The main benefit that I see for SMD is that the components are generally less expensive. The build is also going in the right direction with respect to the Raspberry Pi since the newest Raspberry Pi's are using the same form factor as the B+ model. The model B, A, and A+ form factors are obsolete. SMD builds cannot compete with DIYers since they generally do not yet possess the skill required to solder SMD, but want the satisfaction of building something themselves. However, it does allow people like myself to provide pre-soldered SMD boards for cheaper than it would cost the DIYer to assemble a through hole HeaterMeter from scratch. Different niche markets. :)
 
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