Introduction: Another Sous Vide Controller
Straight from Wikipedia: Sous-vide (/suːˈviːd/; French for "under vacuum") is a method of cooking in which food is sealed in airtight plastic bags then placed in a water bath or in a temperature-controlled steam environment for longer than normal cooking times—96 hours or more, in some cases—at an accurately regulated temperature much lower than normally used for cooking, typically around 55 °C (131 °F) to 60 °C (140 °F) for meat and higher for vegetables. The intent is to cook the item evenly, ensuring that the inside is properly cooked without overcooking the outside, and retain moisture.
I've seen plenty of home-brew controllers for your crock-pot and decided to go with a more compact version that I plan on giving family for Christmas presents.
I have about $100 in building 4 of these units. So $25 a piece is not too bad.
The magic is in the cheap controller that measures the temperature of the water and then turns on and off the cooker(any crock pot) to whatever degree you have set it to. If you set it to 140 degrees, it switches a relay that turns on the receptacle on the side of the unit, until it hits that temperature. After which, it turns off until it registers a temperature drop of 2 degrees, then it repeats the cycle.
I hope the following instructions are clear enough that you dont end up with a mess. This is my first instructable.
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Step 1: Parts List
As of 11/15/15, these links were the cheapest I could find parts.
Temp control unit: $10.98 from a California seller via Ebay http://r.ebay.com/CYi4Ka
C14 Plug: Scrap one from an old power supply, or pay $3.66 for a package of 5 from china via Ebay http://r.ebay.com/Ic2rww
Receptacle: $2.50 at the local Walmart
Project box: $5.29 + shipping... I purchased 4, so it worked out to $9 each after shipping. You may want to fish around for another supplier of Hammond project boxes http://goo.gl/98Z2KZ
14ga solid wire(the stuff in your house walls)
Epoxy for plastic
Whatever else you have laying around that might help the build.
Step 2: Tools and Other Useful Items
Basic stuff like a solering iron, solder, drill, file/sandpaper are pretty necessary for this build. But it is not set in stone, so if you can work around with what you have, go for it!
The epoxy is LocTite plastic which worked surprisingly well.
Also, the jigsaw blade (T119-BO) buzzed right thought the plastic without leaving behind a mess. Just keep the saw at medium speed and let the blade do the work. Dont push too hard and dont let it chatter.
Step 3: Printing a Template
Since I was doing 4 of these units, I decided to draw the cutouts I needed to do with a CAD program(lots of free ones out there). If you are only doing one unit, skip this step.
I found a label sheet, printed my cutouts on it and quickly realized that it would not work because of all the little labels that I would have to peel up and put back together again on the box. So I put a layer of masking tape over the label sheet and reprinted. The print wasn't very dark, so I had to go back over the lines with a sharpie. Then I used a straight edge and cut it with a utility knife.
When I peeled the waxy paper backing off, it left the labels stuck to the back of the masking tape, which wasn't an issue at all. I just stuck the whole thing to the box.
Step 4: Protect Your Box, Drill and Saw
It's a good idea to tape up your box so you dont scuff it too badly while handling it.
Also, run your knife along your lines and 45 degree cut the corners. The reason why is so when you drill the corners out, you wont pull up all the surrounding tape, just the little corner piece.
Speaking of corners, I guesstimated that the corners of the receptacle were 1/4" in diameter. So, with my eyecrometer, I measured 1/8" away from each line and drilled the corners. I would recommend using a more accurate measuring device.
After the corners are done, saw along the inside of the line. Be especially careful that you stay inside because there is no way of hiding these cuts. It's always easier to under-cut it and come back with sandpaper or a file to finish it to the correct opening size.
Speaking of sand paper.. Find something flat that fits in the square hole and wrap the sand paper around the object. You can tape it if it slides around too much for you while you are sanding.
Step 5: Fitting Your Parts
Now that the holes are cut, go back through with a knife to deburr the corners and sand/file as much as necessary to get the parts to fit snugly.
Step 6: Mock-up and Wires
Once they fit properly, do a mock-up of where you want everything. I gave the wire plenty of extra length so I could easily slide shrink tube back up and out of the way while I soldered.
One thing you'll find with this arrangement is the access to the screws on the temp control unit are not accessible. Nor is one side of the receptacle. So you will have to mount long wires on the unit, slide it in, guesstimate the length of the hot wire then cut and screw it down. It's a little tricky, but after a pile of short wires that you can use for anything, you'll figure it out.
Hopefully the picture helps with wire locations.
Step 7: Solder, Shrinktube and Glue
Once you have the wires where you want them, slide a small length of shrink tube up them and lay down a nice solder connection. Then slide the tube over your beautiful work and hide it. Then use a heat gun or lighter to shrink the tube in place.
I left the earth wire for last so it was out of the way for neutral and live.
VERIFY the thing works! Plug a lamp in the end with it turned on, plug a power supply cable in the side of the unit and temporarily place the lid on it so you don't electrocute yourself. Then plug it into the wall. Set it to a few degrees above room temperature, then grab the probe with you hand to warm it up. Once it's warm enough, the light will turn off. It's kinda fun the first time you do it. You can set the temp by holding the S button for a few seconds then use the arrows to find the temp you want, then S again to lock it in.
Once you are happy with wiring and part placement, glue it in place.
Mix small amounts of epoxy on something you plan on throwing out (I used tape. I hate it when my paper or whatever slides all around when I'm mixing). Slobber it all over and pay special attention to the vertical sides. That's where most of the force is going to be when you push buttons or plug things in. It's a good idea to go over these areas a few times, so be prepared to wait 15 or so minutes before making new batches of epoxy.
Step 8: Closing the Lid
Once the insides are sticking in the right spots, lay down some more epoxy around the inside lip of the box and tape it all together. I had to use a clamp around the plug because it was bulging out a little more than the other walls.
So I hope everything worked out for you. If so, give me a Yay! in the comments. If not, well...