To control the environment in a fridge for air drying meat, I wired together 2 controllers, one for temperature, and one for humidity. Once I find a suitable fridge, I will use this until Matt and I can find the time to resume work on the Arduino based fridge controller.
First I wired them up to see if they actually worked. Here’s the mh1210 temperature controller hooked up to a lamp to test it
And here’s the WH8040 humidity controller being tested
So far so good, time to wire them up together.
I cut out a plastic project box to house the controllers and the electrics:
Initially I was going to have 2 mains power inputs (one to each controller) but after I’d cut the holes I decided to have a common power in, so the power socket on the left is not in use:
It seems that most people buy the STC1000 temperature controller, and that’s what I thought I’d bought when I ordered this one. I also thought I’d bought from a UK Seller, but hey ho, that’s eBay for you. The STC1000 does both heating and cooling, the MH1210 only does heating or cooling. Not both. But that’s fine for my purposes.
I started on the wiring. The manuals for these controllers are written in fluent Chinglish, and are utterly useless, so I hunted down some instructions on the internet (yes I know). I found the wiring diagram for the humidity controller on Ben Starr’s blog. Thanks Ben, that was very useful. He also goes into more detail on that page than I’m doing here, including how to set the controllers up from the “intuitive” menu system. Have a read, it’s a good post.
I found the wiring instructions to the temperature controller on a homebrew forum post. Sweet. Just needed to amalgamate the two.
So. Using my newfound “manuals”, and my almost complete lack of electrical wring knowledge, I set about wiring it all up. And here’s what it looked like when I’d finished:
The power comes in through the socket on the bottom right, into the blocks (which go to both controllers), then the power out from the humidity controller goes to blocks 1&2, and the power out from the temperature controller goes to blocks 3&4. The appliances are hardwired into these blocks.
That’s it! Pretty simple – however – if you do this and hurt yourself, it’s your own stupid fault, not mine. K? K.
So I plugged in my RCD into my surge protected socket, pulled on my wellington boots, closed my eyes, held my breath and flicked on the mains power with a broom handle. Much to my surprise it booted up fine first time, and here’s a quick video of it in action – apologies in advance for filming it using a potato.
Pretty pleased with that! You may also have spotted the fact that there’s no earthing going on in this wiring, which is entirely true. When I finally come to wire the fridge into it, the fridge will need earthing, so I’ll do that at that point. Until then I’m just looking for a large larder fridge to use this with…