… though I can’t find said promise; maybe I felt guilty and retconned it out of existence.
I’d like to say I’ve been busy working on pumidor stuff, but the truth is more like “I’ve been busy with school and started giving a shit about working on my pumidor again about two months ago”.
This is the tentative result of my shits-given. If any of my physics professors are watching, axis labels are incoming, I promise (along with a bunch of other improvements/features). It’s come a long way from my first efforts (as has my hoarding, apparently).
So what’s the deal?
A $5 wifi-capable computer, a couple of $3 sensors that are grossly overspecced for the application, and some basic electronics project supplies gets you a control system that will monitor your pu and send details to The Cloud(tm). Another ten bucks’ worth of fans, heat-pads and some transistors to switch them and you have a full-fledged environment controller. Maybe a DC-DC converter if you want to run the controller off the same 12 supply as the heat/fan.
Building such a controller requires basic familiarity with Arduino controllers, but is relatively simple. I’ll write up a wiring diagram the first time anyone asks for one. Asked and received!
Source-code is available for the controller (still something of a work-in-progress) and the django application that runs the website (very much a work-in-progress).
So what does it do? Broadly-speaking it keeps your tea within whatever range of temperature and humidity you desire (a setpoint +/- whatever hysteresis you set). If you have multiple sensors it attempts to control the average value, but allows you to set hard limits (for example, mine attempts to control to an average of 68%RH, but the humidifier will switch off if any sensor reads above 73%RH – as you can see there’s a large delta between upper and lower sensor for my pumidor, which is imperfectly-sealed). If it fails to achieve the desired parameters for a given length of time, it yells at you.
As for the website, I still need to figure out what I want from it and if anyone else is likely to ever use it, but eventually it should provide all the charting gimmickry one could want along with the ability to change storage parameters remotely and export data in a meaningful fashion.
If anyone dabbles with PCB-fabrication and has any hot tips on how to design/fab them inexpensively, I’d be very interested to hear from you – the only thing stopping me from making these available at a halfway-reasonable price is the fact that soldering trace-wires is a pain.
Dead Leaves Club 
Really interesting article. I will watch this project with great interest. Unfortunately, I lack the engineering know-how to replicate this myself and so must be looking to a turnkey solution if I travel down this route. In the meantime, I’ll just keep managing the humidity manually while keeping the temp at room temperatures like I’ve done for the past several years.
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I’d be curious about the wiring diagram.
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Click to access pumidor_wiring_diagram_rough_esp8266.pdf
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Oh and another question: How are you powering it and how long would something like this, maybe without fans, just the measurement, run off of a battery?
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If you wanted to run a system like this off a battery, you’d need a clever power-management strategy – the power consumption of the Wemos D1 Mini is relatively high.
Assuming you wanted to keep the wifi for ease of use, I’d suggest setting up a system whereby a low-power-capable controller (say an Arduino Nano or Pro Mini, using the rocketscream Low-Power library) is used to switch power to the Wemos. For example:
– Nano turns on power to Wemos (either using a DO pin or a relay/transistor)
– Wemos starts up, initialises, transmits a datum via HTTP, then drives a DO pin high.
– Nano, monitoring the Wemos’ DO pin with a DI pin, waits for it to drive high, then goes to sleep for an hour (or however long) and repeats the process indefinitely.
Of course, you could also just use a low-power-capable controller and a wifi shield to begin with, but this would require more work to figure out and get working
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Hey! Nice project, and something that I have had on my to-do list for quite a while as well.
You can create a layout for your PCB with software such as KiCad, and PCBWay is a very low-cost PCB manufacturing house which I have used in the past and been happy with their work.
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Ah, thanks very much for the recommendations!
I’ll give KiCad a try and see how it goes.
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