DIY sous vide controller - HOW??
I'm trying to gather infor to build my own slow-cooker sous vide rig, but I am running into a wall when I seek HOW to put together the controller. Keep in mind, I am woefully out of my league in terms of electronics. So the questions really are:
1- Have any of you done this?
2- What specific items do I need to purchase?
3- How do I assemble/connect them?
Some of what I have seen online -- again with only the most cursory of explanations -- looks like a next of wires. So that my wife doesn't freak out, I'd like to have a neat installation.
First off, what exactly are you trying to build? A basic home-wired PID that you can hook up to a slow cooker?
Some of the comments on that video might be helpful to you.
Do you want to add a circulating component to that set up?
Or a full-on homemade immersion circulator?
Keep in mind that for a worst case scenario, you can just buy a PID designed for this purpose for ~$160. It will probably be a little easier to tune (for tight temperature control and low overshoot) than a homemade one.
This one works:
I posted this one awhile back and no one seemed to notice.
A friend and I put one together for darkroom work--another process that requires precise temp. control. If the frau doesn't like its looks, then either hide it or show her the price tags on commercial units.
I had very good luck using a large cast iron dutch oven (12 quart or so) and using my stove to regulate the temp. The large volume of water makes it pretty easy to keep the temp withing 2 degrees of what you want. My first try ever and I was able to make a steak come out juicy and tender at 135 degrees. I have an electric stove top, used Low, 1, 2 (out of 10) and had no problems keeping the temp within a few degrees. If you get a swing too drastic in either way just add ice cubes or boil some water for q quick fix.
"On my stovetop, my enameled cast iron Dutch oven wouldn't go any lower than 145F."
Ovens basically work, but they're not very precise and they take forever to stabilize on their own, so it's only really good for either maintaining a water bath whose temperature you stabilized elsewhere for a short while (e.g. you're cooking chicken breasts at about 140, so you put the chicken in a pot, bring the pot to 140 on the stove, and then put it in an oven set to 150 for an hour and a half), or maybe for a really long, semi-imprecise cook time like that you might use for .short ribs.
The stovetop really is easier. Just use whatever pot carries the most water. ideally 10 quart or above. It doesn't have to be cast iron - a cheap, thin 16 q stock pot works better than an 8 q but more massive dutch oven.
My problem (thus far) w. my stovetop is that at its lowest setting, which is"1", goes to (and stays locked in at) 145F. Spectacular for anything I want to cook at 145F. But I want to cook some things lower than that. (I'm thinking down to 125F)
I MIGHT set a smaller pot inside a larger one also filled with water to see how that, er, pans out. Also curious as to what temperature my slow cooker registers on "warm."
Thanks for setting me straight on the matter of volume...will try with my stock pot, too.
"My problem (thus far) w. my stovetop is that at its lowest setting, which is"1", goes to (and stays locked in at) 145F."
No offense, but that sounds sort of implausible. So if you start a pot of cold water, it goes up to 145 and then stops there? I guess there may be some theoretical point where evaporative cooling balances out with energy from the burner for any given water volume & pot shape & burner setting, but I assure you that your stovetop is not limited to only one temperature of water bath. Even something so simple as putting a lid on your pot will change your results and cause the temp to slowly rise.
I'm fairly certain your problem is mainly that you don't have/don't use a pot big enough to avoid a slow temperature rise on the lowest setting. If your pot is big enough, you should be able to achieve 'stabilization' at whatever temperature you want. Your stock pot on the stove will work just fine assuming it's reasonably big.
"I MIGHT set a smaller pot inside a larger one also filled with water to see how that, er, pans out. Also curious as to what temperature my slow cooker registers on "warm."
Again no offense, but you're making this more complicated than it has to be. I'm not seeing the benefit of putting one pan inside another. And a slow cooker will not achieve a stable temperature until it's boiling or simmering or nearly so, even on 'warm.'
Let me be more specific.
On Monday, having nothing better to do, I put my Dutch oven (enameled cast iron, 8qt) on the stove, filled with room temp. (75F) tap water set on low. About 45 minutes later, the water temperature had reached 145F. 4 hours later, the water was still 145F. I would have kept it up longer but I got bored and lost interest in checking every 20 min.
My thinking was to insulate the water vessel, that some of the heat coming from the burner is insulated, but you may be right that this would be a benefit-free complication.
It's interesting that your temp stabilized on its own at 145. Nice to know if you ever want to cook at that temp (which is quite good for pork shoulder and pork belly btw, and not bad for chicken breast or short ribs).
But yeah, if you used even a slightly larger pot, you'd get very different results. Ideally you get the water bath up to temp on a higher setting, then turn down the burner so it is as close to stable as you can manage. To do this, you need a pot big enough that a cooking-temp bath slowly cools (or stays the same temp) when on the lowest setting on your stove.
Keep in mind that adding food to a bath will destabilize it and cause the temp to fall.
I don't think if it is worth it to DIY a controller. I don't think you will save much money making it yourself. If you are not already handy with electronics, then you have to kit yourself out with soldering irons, drill, drillbits, wire strippers, etc which will add to your cost.
I have inherited a Sous Vide Magic controller which you can get new for $159. You then get a cheap rice cooker and an aquarium pump and you're in business. It is a pretty well made controller - albeit a bit industrial looking.
If you are handy with electronics, Auber Instruments sells integrated control units which you then encase and wire. They also sell a complete turnkey unit. (I suspect that my Sous Vide Magic is actually a rebranded Auber). If you want to DIY, Auber sells all the bits and bobs that you need (control unit, sensor, cases, switches, etc).
If you are a real hacker, Google "Arduino PID Temperature Controller". With Arduino, you need to be into electronics and computer programming.