@FieldEffect that really is a slick contraption you built. It might inspire me to do some tinkering.
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Made a quick video
Seems to be working decently, it wasn’t designed to run well during mid-summer, but here we are. The gorilla glue is awesome but it took a few days for the smell to dissipate. This has been running since Friday, first in my house, now out in the shed where it’ll live long-term.
I’m going to duct the inlet up to the wall vents so I get fresh air in, and use better filters when the time comes to actually put some herb in it. They’re both (circulation filter and inlet filter) standard 10x20x1" filter assemblies for furnaces, got a 3 pack of MERV-11s for about $20. I’ll run a MERV-13 circulation filter (the one inside under the racks) during harvest season just to keep things clean inside.
IT WORKS!
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This is a masterpiece!!
I def. Going to build one
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Thanks!
The software on the controller is getting some work done, I’m going to plug in another T/RH% sensor and use it to calculate the amount to run the exhaust fan to hit a target RH.
I’ll have to make another video of how the existing UI works, it’s pretty simple. You set what RH the exhaust turns on, how long it runs, how long to wait. Also the heat/cool/humidify/dehumidify options are all working but not used yet.
I made the lower section of the cabinet tall enough for a small amazon dehumidifier or humidifier, we’ll see if I need it. Simple to add now if I do.
I’m using draft seal foam tape on the door/cabinet interface to seal it up and it requires quite a bit of pressure, I think I’ll need to figure something else out but the velcro is decent (clunky though).
I think really it’s just the controller that makes this special, I’ll release all those files soon. I’ve got some extra boards that require soldering if anyone wants one.
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These are for curing my meats
I mean, this is for aging my cheese
Fine, it’s for weed.
I like the “must sign in” on the door.
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I’d hate to guess what they cost new but I doubt they’ll get pennies on the dollar for them.
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Gonna need 3 of 'em 
Meat cellar, cheese cellar, weed cellar.
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So, my autoflowers have about a week to go, going to get this show on the road. Going to be more closely monitoring trichomes and preparing for the chop. It’s been over 100 for a few days in a row and expected to continue, so I’m experimenting with ice in the water cooler to keep the internal temp down.
So far we’re holding at 60 but I’m playing with some ice packs and whether or not I can maintain sub-70 temps by swapping ice packs every morning before I head to work. Otherwise I may need to supplement with some ice, but this is surmountable. Remember, this was designed for late-fall operation, 110F shed temperatures were not something I planned on. Entertaining whether or not the SO would permit this to migrate into my office, granted it’s probably going to stink soon.
Thinking about this more, absolute humidity (amount of water per cubic volume) needs to be a criteria taken into account. For example, air at 100F and 25% RH contains more water than the interior of the cabinet at 60F/60%. I made this table for convenience, this is easily calculated in the microcontroller of the cabinet on-the-fly:
Anyway, I’ve been musing about VPD. Perhaps this is the best metric to control? It’s simple enough to use, but if humidity can’t be controlled well enough you can slide the other knob to equate the parameter. Now, drying rate is related to several other parameters but VPD is a good first-order metric. In other words, perhaps I tailor the parameter I can control precisely to match whatever the other is. For me, temperature is going to be less controlled than I thought. Therefore, perhaps I can more accurately tune the humidity to reach an ideal VPD rather than a specific absolute humidity, which is going to vary according to the box temperature. Again, made a chart. This is similar to the AH computations and readily realizeable on the microcontroller, so using this as a process variable would be of no negative consequence.
Example: If we said we were trying to maintain VPD = 0.7kPa, and my temp drifts to 50F after I add the ice pack, I’d want to be controlling for a new RH of around 43% rather than 60%.
Intuitively, the vapor pressure differential is going to dictate the evaporation rate. This sounds like a reasonable path, any ideas?
FWIW the Cannatrol uses dew point which I find interesting. It’s a derivative of water saturation pressure for a given temperature. I don’t understand it’s use as a control metric although it accomplishes something very similar to VPD but less directly. Perhaps they aren’t explicit about it so it intentionally seems more obtuse the VPD.
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cool, almost time for the test run!
trying the ice seems reasonable. as far as VPD goes…maybe too clever? I’d rather hit the humidity number more than anything else. if the temp climbs to like 65-70…meh, that’s the way she goes. it’s the desert…
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I am really geeking out on this whole thread. Will you provide gerbers and the program for those of us who lack the acumen to actually do this for ourselves? I can think of a bunch of applications, meat, cheeese, koji, mushrooms, proofing bread, etc. anything where temp and humidity must be controlled accurately. I was going to convert a commercial undercounter fridge to grow koji, and a commercial 2 door stand tall for a grow cabinet. My thought was to use 2 inkbird controllers for each.
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PCB doesn’t have any issues, I actually just tried to upload it. Guess I’ll need to figure out some other hosting location, maybe github or something like that. It seems I can only post pictures here. In the meantime, send me a PM with your email and I’ll send you all the HW files (zipped directory with pdf schematic, excel BOM, gerber files).
Firmware is still a mess but absolutely I’ll send that too. That will be in a better state soon, drying is about to start!
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HERE WE GO!
The basic wash setup. Bud wash lemon juice/baking soda, water bucket, final rinse distilled water. Just trimming fan leaves for now so they rest nicely in the trays.
Mmmm…cloudy trichs just 5% amber or so, keep the Super Lemon Haze Auto “uppity.”
Runtz XL Auto top, SLH in the bottom tray. Just drying off the excess wash water in the sun for a few minutes. The Runtz is pretty ripe, the SLH is just shy of that, trying for a more “sativa” effect.
In they go! Room for lots of company, I hope it gets stuffed full by the time fall comes.
5 minutes into the run we seem to be pretty stable temperature/humidity.
I’ll post updates as this goes along, I’m excited to see how it works for real! I’ve got the circulation speed set fairly fast right now, I’ll turn it down once all the external moisture is off, maybe in a few hours.
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Just created a repository for it. The full-basic-function firmware is also listed there, some of these more sophisticated features I’m not comfortable releasing yet. This is a full-function temperature control with heat/cool outputs, humidity control with humidify/dry outputs, PWM-fan speed control for 3-wire fans (2 channels). This should be all that is needed, if I forgot something let me know. I have some extra boards I’d give to anyone that would build one!
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That is a nice tidy package you have put together. 
Well done!
Cheers
G
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It’s fun to create devices and use them. I did that for a living for half my life and I created my own curing/breeding box. It is convertible by switching a few plugs. It can hold a couple pounds of hanging buds or one male and 3 females for breeding. The air is filtered in and out to stop the spread of pollen and is easy to clean after a breed. It’s not as nice as yours but I use it often and have bred in it about 15 times in 4 years. And now that I’m fully stocked with seeds I’m retiring from breeding after the current breed that is lined up for the box in a week.
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There is life after breeding? 
I’m curious, what are you planning to do for fun?
Cheers
G
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Thanks for the positive feedback!
Interesting, using it for breeding/drying. Makes sense to filter both sides in both cases.
I’m still young, and still doing it for a living (making things, not breeding as much as I’d like). 
I get to make some really cool stuff, and certainly enjoy it.
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Right now do cool stuff with the wife and live pollen free after replenishing my Thai Seed Bottle(almost pollenating). I’ll probably find some way to do a seed share in Canada for a grow and show. I’m packing some serious heat in my seed drawer so I can have fun with that as long as I don’t spend much on postage.
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I wish my dryer was more automatic like humidity controlled. I’ll probably change up the controls after I’m sure I’m over my seed breeding addiction. I can then remove the lights also. I’ll probably do 2 final breeds after my Thai seed replenish. An F4 run on my Red GSC in a month and a CBD seed run next year. I have a miniature grow so auto drying is a luxury I hope to enjoy one day. Most of the cost are already paid and just need to finish my breeding before swapping the controls.