STC 1000 "Ebay" Temperature Controller Build

This can happen if you don't insulate the probe or secure it to the fermenter well enough. With the probe uninsulated, the controller can cut off the heat/cool way before the wort is at the set point, so even with the carryover it doesn't quite get to the set point, and after temps reach equilibrium it has to turn on again. With the probe insulated the controller generally cuts the heat/cool off just before it reaches the set temp, but there's still some carryover, which then usually takes the temp very close to the set point.

There's always going to be carryover when changing temps, and the amount depends on the initial temp differential, and the thermal mass and specific heat of the system components. The most elegant solution for this is using fuzzy logic or PID type controllers. With a simple on/off type controller, different sensor placements can help neutralize some of the temp lagging.

As I've already mentioned, the overshoot is only noticeable when the wort temp is different from the set temp of the controller, and the greater the difference the greater the overshoot will be. If you cool to your ferm temp (or very close to it) before placing it in your ferm chamber, and never ramp temps up towards the end of fermentation, or cold crash in your ferm chamber, you'll likely never notice it. If you need to change temp more than a couple degrees for any reason, you'll likely notice it.

And it's not exactly the type of ferm chamber you're using, like fridge vs chest freezer vs upright freezer. It's the thermal mass and specific heat of the fermenter, ferm chamber interior walls, and shelving/contents (other than the fermenter full of wort).

There's probably slightly more overshoot when the cooling system transfers a lot of heat really quickly, but there's not a significant difference in this regard between a chest freezer and a fridge. There is however a huge variety of heat sources I've seen people using in their ferm chambers. Someone using a 1500W space heater is going to have more overshoot problems than someone using a 40W light bulb in a can.

 

I ramp temps at the end of my ferment, but I usually do it slowly (1-2 F per day). In the end, I have a few days before my next scheduled brew day. Once my thermowell gets here I am probably going to put some water at my usual pitch temp into my fermentation chamber, then run a few tests in two configurations:

- Insulated probe on the side of the BB; Thermowell installed but with a thermometer only in the thermowell.

- Thermowell installed, but with both the STC probe and my thermometer probe in it. (or with my thermometer probe taped to the side of the BB. Haven't decided yet. Does the STC provide a temperature readout of what the probe is sensing? If so, I may just tape my stand alone thermometer's probe to the outside of the BB in this configuration)

 

The STC1000 I have will show current probe temp when it is on. Then pushing one of the arrows will show target temp.

 

I apologize in advance if this has already been covered, but I didn't turn anything up in my searches.

This weekend I assembled the parts at Home Depot to build a temp controller using an STC-1000 and 2 decora duplex outlets. For the enclosure, I chose one of the blue Carlon 3-gang outlet boxes and a 3-gang decora wall plate. Unfortunately the outlet box has some ribs that stick out on the interior and prevent the STC-1000 from sliding all the way into the enclosure. Can someone recommend another enclosure that's deeper to use for my build? Something similar to that outlet box would be great as it was cheap and didn't require any cutting or drilling, but perhaps such a thing doesn't exist.

Thanks for your help.

 

How about a deeper box design? Carlon 3-Gang 53 cu. in. would cutting the mounting tabs off be any problem?

 

That looks like it should work but it's apparently not available in store. However, that reminds me that I saw a similar outlet box when I was in the store but steered away from it because of the large nails sticking out of the sides. At the time I didn't notice (or care) that it was deeper, but looking at the specs I think it might work. I'll definitely bring the STC-1000 with me to the store this time.

The tabs on the one I got are tough to reach and would leave holes if I get rid of them completely.

Thanks very much for your suggestion.

 

Why not use a plastic project box, they seem to have a bit more space then the electrical "gang" style boxes.

 

All things being equal, I'd rather avoid the drilling and cutting that a project box would require. Plus the outlet boxes are quite inexpensive. But a project box is certainly my next purchase if I can't find a suitable outlet box.

 

All of the builds I've seen that use outlet boxes require cutting the ribs off of the interior to get the controller to fit, even with the extra deep boxes. You also still need to cut the cover plate since the decora rectangular openings aren't quite large enough to fit the controller either. I'm not sure that using an outlet box saves much if anything in the way of cutting.

 

I have built several in the project enclosures and it's the easiest route in my opinion

 

I have used a 3-gang home depot "old work" box and the STC fits just fine after you grind the tabs down. Then you can have a heat-on, cool-on, and a couple always-on outlets. Just make sure you I incorporate a fuse in the design.

 

Here's mine with heating and cooling outlets.

 

My return trip to Home Depot for a deeper outlet box was not fruitful. On their website they refer to the dimension I'd call "depth" as "Assembled Height", which threw me off.

So what's a good source for project boxes? I looked on the Radio Shack website and the largest one I found on there was 8 x 6 x 3 which seems like it would be pretty cramped.

Thanks again.

 

I got my project box off amazon - they have a tee duos selection.

 

I just finished grinding down my second box. I use a three gang old work box, and throw away the plastic flap from the STC. Then I use a dremel to open it up a little more. It fits pretty well without punching unnecessary gaps in the box. Have a look:

 

This is my other finished unit.

 

this is the schematic I used, similar to the one gatorbite87 uploaded in the first post, but also includes a fuse (use a 10-amp slow blow) and the second 'constant on' outlet. Just be sure to use 16AWG or 12AWG wire.

 

STC-1000 cheaper than ever - $17.79 on Amazon (US shipper).

 

Thanks for the tip. I was having space problems until I threw away the plastic flap from the STC-1000.

 

Can someone tell me if you can dim the display screen on an STC-1000? I'd like to mount one in my keezer collar but the keezer is going to be positioned next to the TV. Not sure if it's going to be too distracting having the display glare at you while watching TV in the dark. Thanks!

 

Maybe some window tint scraps?

 

^ That's a good idea if indeed those big bright digits are a problem, as there is no "dimmer" control on any of these tiny digital controllers (even my pricey TSS2 doesn't offer that feature).

My bet is unless it actually is reflecting off a big screen it'll eventually be nearly unnoticed...

Cheers!

 

Maybe some translucent grey (smoke) acrylic sheet

 

Color it with a Sharpie? lol.

 

I bought some of these for my bedroom TV and cable box

http://www.lightdims.com/

Work really well and excellent customer service!

 

Thanks for this super simple wiring diagram...

Made it easy...

 

As I'm not really good at reading schematics, could someone tell me how this is supposed to be wired correctly and what the component is on the left side after the plug, the 12v 1 amp part....sorry for such questions but don't know these things and want to rewire mine to use it with higher amps...thanks

 

One page back I posted the simplest schematic possible to get this going, I hate being a douche but if you can't follow it you probably shouldn't be messing with electricity. I say with deference to please have a look at a Johnson control unit, which is premade.

 

Hey BeerGrylls......appreciate the concern and that is good advise...I already have one wired as your pic shows but wanted to upgrade one of mine to allow me to use higher amperage, but didn't know what the part was in the drawing...still don't so can someone tell me what it is....reminds me of a transformer or something along those lines ....thanks

 

I think you're referring to the transformer.

 

The 110v model will handle up to 10 amps. Anything over that will require the use of relays, ensure that you get one that uses 110VAC control voltage, and can handle the load. Once you get into this range, keep in mind that component heat will also rise, so you'll need an enclosure that had proper dissipation through radiation or some other method. How many amps are you trying to drive? Or are you trying to step up the voltage? What is your load?

 

I need to run as long as possible a length of Flexwatt heat tape around some gallon jugs of beer that I'm making as an experiment...so I need to be able to extend the wattage that the STC-1000 will handle without having to buy, in my case 12 more STC's as each foot of 4" of Flexwatt needs 8 watts of power.....so one per gallon jug can get a bit expensive....any other ideas appreciated

 

You're right, I imagine the STC could handle quite a bit of that heat tape without jumping through extra hoops. Good point about the short circuits though. Exactly why I recommend a fuse, because it will cover you against exactly that.

 

I've seen that many of the STC-1000's for sale on Amazon and eBay include a temperature sensor. Has anyone installed one of these included sensors into a thermowell inside a carboy? Or are people only using them in open air inside their ferm chambers? Thanks!

 

They all come with a probe, it's basically a thermocouple with a two-wire lead. I'm not sure it would fit into a thermowell without a little modification, but I seem to recall this question coming up before, and someone else measured the probe that came with the unit.

EDIT: Found that data, it's 0.25" as stated in this post: http://www.homebrewtalk.com/f51/stc...troller-build-330427/index22.html#post5604942

 

Thanks for that. Good reading in/around that post. I've ordered the bits to build a controller, but I don't yet have a plan for controlling fermentation temperature. I'm trying to decide between a liquid cooling strategy (Cool Zone) or a mini-fridge (low SWMBO factor). If I go with the Cool Zone approach, the only real option is thermocouple.

 

There was some agreement that the best method is to tape the probe to the side of your fermenter. This was a compromise between air temps (quick to change) and wort temps (slow to change).

 

These actually come with an NTC thermistor. If you want to use pretty much any thermowell then all you have to do is buy the same type of thermistor (10K, B=3435), like below on eBay and they are so small they'll fit anywhere. They are literally dirt cheap and all you have to do is solder two wires, there isn't even polarity to worry about, and drop it down into your well. I make my own custom probes this way - I basically made a 40cm long probe for a few dollars

http://www.ebay.com/sch/i.html?_odk...0k+3435&_nkw=ntc+thermistor+10k+3435&_sacat=0

EDIT: Here's a photo of the aforementioned probe - the "insert-phallic-reference-here" probe ...

 

Nice probe! LOL. Love the shrink wrap. I may have to give that try. Definitely cheaper to roll your own.