I am having trouble finding the display and the 2700uF cap. Backordered everywhere. Any ideas?
| Part# | Description |
|---|---|
| C1 | 35V, 2700uF, Rubycon Electrolytic |
| LCD1 | I2C 16x2 LCD Module |
Any display alternatives that anyone can recommend?
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Howdy Greenup!
C1 This would be a fine substitute at 2200uF 35V same physical size
The capacitance isn’t so much an issue here, I actually picked the 2700uF part I did because it was inexpensive and readily available…last spring at least 
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Awesome! Thank you for taking the time to provide alternatives. Excited to be getting the parts ordered. I had to get some other projects finished and an old shuttle bus sold. I will post an update once I get the electronics together.
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@FieldEffect Rather than go private message I figured I would post my questions in case they help someone else.
Can I use one of my older nano knockoffs or do I need to get the specific ATmega4809 in the BOM? The nanos I have on hand are “Nano V3.0 Micro Controller Module, UCEC USB Development Board ATmega328P CH340G 5V 16M, Compatible with Nano”
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I don’t think the code would run as-is. I can take a better look this weekend but I remember having to do some register manipulation for the fan PWM that probably wouldn’t port over.
If you are comfortable with Arduino programming I’m sure you could make it work, but I’d just get the same part if I were you.
Thanks @FieldEffect ! I don’t mind buying the correct nano, it’s just that I have 6 I am not using haha. Thanks again for your valuable input
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@FieldEffect If you get a minute could you link me to an in stock SHT31 Humidity and temp sensor you would recommend?
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I used this one: DFRobot SEN0334
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Shoot, i had that one marked but i wasn’t sure if i made it up or what. Now i see you did link to it earlier in the thread. sorry to bug ya.
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No worries 
I finally got it all ordered, i hope! It was quite the multiday adventure trying to find all the parts or compatible. Each day new stuff was out of stock. Luckily I have some experience with electronic components from working on pinball machines else I don’t know if I could have done it. Comparing spec sheets on components is not fun.
Anyway, if someone else wants to click click buy… this saved cart might work for a bit https://www.digikey.com/short/4w4q973f My total shipped, taxes, and tariffed was $114. This should be everything you need to build the controller (plus the unpopulated board).
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@Greenup, let me know how it goes.
After a considerable amount of thought, I’m creating another version of firmware that does absolute humidity control. This is expressed as grams/cubic meter. I will make a conversion table to go from Cannatrol dewpoint settings to this metric. The recommended setting of 68F 54F dewpoint equates to 10.6g/m^3. AH and DP control essentially the same thing. I’m curious how this will go and will make this firmware version available.
DP calculation:
=243.04*(log(fhum/100)+((17.625ftc)/(243.04+ftc)))/(17.625-log(fhum/100)-((17.625ftc)/(243.04+ftc)))
AH I feel is the actual metric we want to control:
=(fhum*(exp(34.494 - (4924.99/(ftc+237.15)))/pow(ftc+105,1.57)))/(46.15*(ftc+273.15));
Those are the Arduino implementations where the input variables are floats fhum (float RH) and ftc (float temp in C).
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Thank you for continuing to post your work on this. It’s a fascinating process to watch unfold and bonus I get to use your hard work as my own and hopefully customize and build on it.
I haven’t really gotten into your software yet… But I have read all your posts here multiple times by now. The software has me most interested but I gotta build it first. I believe all the parts have arrived (in a couple different packages). I am going to attempt to put the through hole and larger components on the board today. My buddy with surface mount tools is at the lake but I hope to get the rest installed early in the week.
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I would wait on the big stuff and do the SMT stuff first. The smaller parts are easier to put down before there are things in the way.
As a note, I do my soldering with a nice iron, 1/8" chisel tip. SMT or through-hole. You need decent flux, 0.015"-0.032" solder should be fine but bigger than that is a PITA. Good set of tweezers is nice, but even crappy ones are tolerable for the size used on the board.
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Ok! I will take your advice and try the smaller stuff first.
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@FieldEffect I just finished going through all the parts and it seems all have arrived but I think I might have ordered something wrong.
On your BOM you have the following
“D1, D6, D12, D14 Schottky Diode, 80V, SMA”
What I got in the mail is
“Schottky Diode, 60V 1A, SMA”
Not sure if they sent the wrong thing or if i ordered the wrong thing. For some reason they also split the 4 diodes into two different bags. I guess my question is… will 60V instead of 80V be ok? On Digikey
Seems like a lot of parts when they are all bagged up!
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Won’t be an issue. I sought to use generic, over-specified parts.
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I’d start with those diodes actually, they are durable and easy to solder. Then I’d do all the 10Ks, etc. I pick a bag up and place all the parts with that PN, and then I move to the next bag.
Happy to see you get going! If you are unsure of anything don’t hesitate to ask.
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Very cool following this and congrats on the work. As a tongue in cheek add on I’m sure there are a couple members of this site who could help. Just kidding but a couple of those who claimed they could do it easily blindfolded cried like little girls when they/he got called out to prove it and went crying to the mods when people mocked them.
You seem to know what you’re doing and have a plan. When you finish this I presume you’re going to test it and I’m curious at the conclusion how much it costs in total. Big salute to you.
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Very thorough explanation. I have been reading about the Cannatrol I would note that what I have read indicates the use of a sponge and water in some manner to add humidity when needed. I don’t see a way to add humidity in this one. Once in the cure stage it would seem like it could be necessary in dry climates.
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