Stc-1000 wiring

[HopSong]

Thank for asking.. I think your posts are great regarding anything wiring.

My only questions, which JuanMoore is helping with, is WHAT probes are available for it? He said there were replacements.. which I couldn't find on eBay.. mentioned also that there are even SS probes. I searched and found lots of probes.. but, have NO idea if they are compatible.

 

[Stauffbier]

Thank for asking.. I think your posts are great regarding anything wiring.

My only questions, which JuanMoore is helping with, is WHAT probes are available for it? He said there were replacements.. which I couldn't find on eBay.. mentioned also that there are even SS probes. I searched and found lots of probes.. but, have NO idea if they are compatible.

Good question! I'd like to know about this as well.

I just wired mine up thanks to Revvy's diagram. I also have a 220V stc-1000 that I've learned how to convert to 110v that I will use for my keezer build..

 

[Revvy]

Thank for asking.. I think your posts are great regarding anything wiring.

My only questions, which JuanMoore is helping with, is WHAT probes are available for it? He said there were replacements.. which I couldn't find on eBay.. mentioned also that there are even SS probes. I searched and found lots of probes.. but, have NO idea if they are compatible.

I recall a post several weeks back about it somewhere on here by Carlisle Bob, explaining about replacement probes for most of the common temp controllers. It was over my head. But iirc he made it seem that for the ebay temp controller finding the correct replacement probe, was nigh on impossible.

I'll try to pm him to say something about this.

 

[Stauffbier]

for the ebay temp controller finding the correct replacement probe, was nigh on impossible..

I've read this quite a few times myself. It seems like there has to be something out there that will work, though!

 

[Revvy]

I've read this quite a few times myself. It seems like there has to be something out there that will work, though!

Yeah. I'm sure there is, and Bob explained it, but it was WAAAAAYYYYY over my head. Maybe he can actually do some digging and link ones that will work for us idiots....

 

[Stauffbier]

for us idiots....

I resemble that remark! haha..

Thanks for looking in to it Rev

 

[JuanMoore]

I recall a post several weeks back about it somewhere on here by Carlisle Bob, explaining about replacement probes for most of the common temp controllers. It was over my head. But iirc he made it seem that for the ebay temp controller finding the correct replacement probe, was nigh on impossible.

I'll try to pm him to say something about this.

I don't know what Bob said, but it's very simple, and there are plenty of options out there. Any sensor of the same type that has the same resistance will work. The sensor for the STC-1000 is a fairly standard type; NTC thermistor and IIRC 10k ohm resistance at 25 degrees C. Emjay has posted a link a few times for the inexpensive SS probes he bought to replace the stock probes in his controllers. I'm on my phone now, but if I think of it later I'll find some links to suitable options and post them here.

 

[Stauffbier]

I don't know what Bob said, but it's very simple, and there are plenty of options out there. Any sensor of the same type that has the same resistance will work. The sensor for the STC-1000 is a fairly standard type; NTC thermistor and IIRC 10k ohm resistance at 25 degrees C. Emjay has posted a link a few times for the inexpensive SS probes he bought to replace the stock probes in his controllers. I'm on my phone now, but if I think of it later I'll find some links to suitable options and post them here.

Thanks Juan! I'd be interested in seeing any links you might have for the SS ones..

 

[emjay]

I'll just leave this here...

http://www.ebay.com/itm/Air-Water-T...-Thermostat-NTC-10K-Thermistor-/110939258796?

 

[emjay]

They're even easier to find (and much cheaper) as simple bare thermistors, if someone feels like making/finding a sleeve for them.

 

[carlisle_bob]

I recall a post several weeks back about it somewhere on here by Carlisle Bob, explaining about replacement probes for most of the common temp controllers. It was over my head. But iirc he made it seem that for the ebay temp controller finding the correct replacement probe, was nigh on impossible.

I'll try to pm him to say something about this.

Hi

Ok, here goes again on the probes:

1) You need one that's 10K ohms nominal resistance at 25C. That's pretty easy, just be sure you don't get ones that are 10K at 20C.
2) You need one that's an NTC (negative temperature coefficient) not PTC (positive temperature coefficient). Again pretty easy.
3) You need one that's pretty close to 10K. A 2% part would put you .7C off, a 10% part will put you off by about 3C.
4) You need one with the right beta or slope. This is where it gets tough. Thermistors come in a wide range of slopes (change in resistance versus temperature rates). On a good controller, the slope of the probe is programmed into the unit on a batch by batch basis. Even if you had a specific number, the data you see is often less than helpful since they don't state test temperatures. Simple answer - the one you get is not likely to be the right slope.

So, can you replace the probe? Yup, can be done easily and cheaply. Will the probe "work"? Yes it will run the controller. No it's not likely to read accurately over a range of temperatures. How wide a range depends on how accurate you need to be and how close your part happened to be.

Is that the full story? - no. It's enough to give you a pretty good idea of what's going on when you try to do a replacement.

Bob

 

[JuanMoore]

Hi

Ok, here goes again on the probes:

1) You need one that's 10K ohms nominal resistance at 25C. That's pretty easy, just be sure you don't get ones that are 10K at 20C.
2) You need one that's an NTC (negative temperature coefficient) not PTC (positive temperature coefficient). Again pretty easy.
3) You need one that's pretty close to 10K. A 2% part would put you .7C off, a 10% part will put you off by about 3C.
4) You need one with the right beta or slope. This is where it gets tough. Thermistors come in a wide range of slopes (change in resistance versus temperature rates). On a good controller, the slope of the probe is programmed into the unit on a batch by batch basis. Even if you had a specific number, the data you see is often less than helpful since they don't state test temperatures. Simple answer - the one you get is not likely to be the right slope.

So, can you replace the probe? Yup, can be done easily and cheaply. Will the probe "work"? Yes it will run the controller. No it's not likely to read accurately over a range of temperatures. How wide a range depends on how accurate you need to be and how close your part happened to be.

Is that the full story? - no. It's enough to give you a pretty good idea of what's going on when you try to do a replacement.

Bob

While much of that is true, you make it sound like there's little to no chance of ending up with a probe that measures with acceptable accuracy in the temp range we're dealing with, which simply isn't the case.

The majority of thermistors out there, especially those that would be found in a probe, have similar beta values at the lower end of the temp range, which is really the only part of the curve most of us are interested in. This is also close to where the slope of the curve is steepest, so any discrepancies in the resistance value have less effect on the temp reading than in other temp ranges. For controlling a keezer, even if you like to change the temp a little from time to time, the range of temps you'll be using is so tiny that the slope (beta value) really doesn't matter much at all. The only thing that really matters in this case is that it's calibrated properly at the temp you'll be using it at. For a ferm chamber the range is larger, but still small enough that using a probe with a slightly different lower end beta value isn't going to create any huge discrepancies. Just like when you first buy the unit, or extend the probe wires, the unit should be calibrated after replacing the probe, preferably at a temp close to the center of the range it will be operating in. I don't know the exact 25/50 beta value for the STC-1000, but FWIW the similar single stage units I use in my control panel are 3435. I'd be comfortable using probes with 25/50 beta values anywhere within a few hundred of that for a keezer or ferm chamber. There's a bunch of cheap probes on e-bay that are 3470, which is more than close enough for me and my uses. At higher temps, or for use over a large range of temps, the issues you brought up become much more important. As always, YMMV.

Edit: And FWIW if the test temperatures for the beta value of a thermistor aren't specifically stated, they're virtually always 25/50.

 

[Stauffbier]

I found this if anyone just wants to buy an original repalcement sensor;
http://www.simplyaquaria.co.uk/STC_1000_Temp_Sensor/p1097265_7286229.aspx

 

[carlisle_bob]

While much of that is true, you make it sound like there's little to no chance of ending up with a probe that measures with acceptable accuracy in the temp range we're dealing with, which simply isn't the case.

The majority of thermistors out there, especially those that would be found in a probe, have similar beta values at the lower end of the temp range, which is really the only part of the curve most of us are interested in. This is also close to where the slope of the curve is steepest, so any discrepancies in the resistance value have less effect on the temp reading than in other temp ranges. For controlling a keezer, even if you like to change the temp a little from time to time, the range of temps you'll be using is so tiny that the slope (beta value) really doesn't matter much at all. The only thing that really matters in this case is that it's calibrated properly at the temp you'll be using it at. For a ferm chamber the range is larger, but still small enough that using a probe with a slightly different lower end beta value isn't going to create any huge discrepancies. Just like when you first buy the unit, or extend the probe wires, the unit should be calibrated after replacing the probe, preferably at a temp close to the center of the range it will be operating in. I don't know the exact 25/50 beta value for the STC-1000, but FWIW the similar single stage units I use in my control panel are 3435. I'd be comfortable using probes with 25/50 beta values anywhere within a few hundred of that for a keezer or ferm chamber. There's a bunch of cheap probes on e-bay that are 3470, which is more than close enough for me and my uses. At higher temps, or for use over a large range of temps, the issues you brought up become much more important. As always, YMMV.

Edit: And FWIW if the test temperatures for the beta value of a thermistor aren't specifically stated, they're virtually always 25/50.

Hi

Last time we had this conversation, you came on pretty strongly that "calibration is nonsense" ....

Some more of the story:

Beta is an exponent in the fit equation. A small change tolerance wise in the beta results in a fairly large change in the resistance versus temperature slope. It's pretty easy to be off by two or three degrees on a ten degree change.

Bob

 

[Stauffbier]

You were right Revvy! These guys are way above my head with this stuff!

NERD FIGHT! NERD FIGHT!

Just kidding guys! It's educated people such as yourselves that help this homebrew community so much! Thanks!

 

[JuanMoore]

Hi

Last time we had this conversation, you came on pretty strongly that "calibration is nonsense" ...

Bob

You must have me confused with someone else, 'cause I've never had this conversation with you, or said anything about calibration being nonsense.

You were right Revvy! These guys are way above my head with this stuff!

NERD FIGHT! NERD FIGHT!

Just kidding guys! It's educated people such as yourselves that help this homebrew community so much! Thanks!

Ha! No nerd fight from me. I really couldn't care less if someone on the interwebs disagrees with something I said.

 

[pjcampbell]

Here is mine.

View attachment 71775

1) What is the piece called that you used to fix the power cord to the box? I was going to drill a hole for an NM clamp but your piece looks better.

2) I bought a 4x4 Marine box at home depot. E989NNJ. But I can't figure out what cover would work with it to put an outlet in there. I would prefer not to cut the hole for the outlet, based on how my hole for the STC-1000 looks which is thankfully covered nicely by the flange.

I haven't figured out how I'm going to do this in general, because the STC-1000 is not rated for working in temps below freezing (according to spec sheet). I will probably have to put the whole unit INSIDE the freezer (which will be outside all winter--obviously not running most of the time).

 

[ChuckO]

1)

I haven't figured out how I'm going to do this in general, because the STC-1000 is not rated for working in temps below freezing (according to spec sheet). I will probably have to put the whole unit INSIDE the freezer (which will be outside all winter--obviously not running most of the time).

The instructions that came with my STC-1000 show a temperature range from -50 to 99 deg. C. That's certainly below freezing.

 

[pjcampbell]

My spec sheet says:
"ambient temp 0C-60C"
"Storage temp -30 C - 75 C"


I took this to mean that when operating, it should be from 0-60C, if it's just sitting around off, then it can go lower.

Our lowest temps are -25F so I don't know if the electronics could break, relays freeze up, etc. at these temps.

 

[ChuckO]

My spec sheet says:
"ambient temp 0C-60C"
"Storage temp -30 C - 75 C"


I took this to mean that when operating, it should be from 0-60C, if it's just sitting around off, then it can go lower.

Our lowest temps are -25F so I don't know if the electronics could break, relays freeze up, etc. at these temps.

You're right, I was looking at the probe temperature range for operation, not the rating for the unit itself.

 

[porcupine73]

I'm working on mine, basically will be wiring like Reevy's post, one duplex constantly on, one duplex for heat, one duplex for cool. I went with a triple gang box and bought a contractor 10 pack of Decora outlets at Lowe's as I'm planning to make up two of these units. I couldn't find cover plates for three standard duplex outlets, only for Decora style. Mine won't be quite as pretty because my plan is to zip tie the stc-1000 to the outside of the gang box, partly because I want it to be facing 90 degrees off from the outlets.

 

[IFMracin]

2) I bought a 4x4 Marine box at home depot. E989NNJ. But I can't figure out what cover would work with it to put an outlet in there. I would prefer not to cut the hole for the outlet, based on how my hole for the STC-1000 looks which is thankfully covered nicely by the flange.

The screw-on cover looks like it would have plenty of room for an outlet and a standard outlet cover to hide most cutting issues.
And they make outlets and covers in grey that would match decent (if that matters)

I did just that with my Radio Shack project box.

 

[jerryk]

1) What is the piece called that you used to fix the power cord to the box? I was going to drill a hole for an NM clamp but your piece looks better.

2) I bought a 4x4 Marine box at home depot. E989NNJ. But I can't figure out what cover would work with it to put an outlet in there. I would prefer not to cut the hole for the outlet, based on how my hole for the STC-1000 looks which is thankfully covered nicely by the flange.

I haven't figured out how I'm going to do this in general, because the STC-1000 is not rated for working in temps below freezing (according to spec sheet). I will probably have to put the whole unit INSIDE the freezer (which will be outside all winter--obviously not running most of the time).

It is a strain relief cord connector. I got it at Home depot. I did have to mod the box to get it to fit but I do like it.



Here is a picture of it apart.

 

[HopSong]

ChuckO and iFM.. are your boxes ventilated? I haven't done anything with mine yet.. but, it looks like they will need a bunch of holes to transfer heat from the electronics??????

 

[ChuckO]

ChuckO and iFM.. are your boxes ventilated? I haven't done anything with mine yet.. but, it looks like they will need a bunch of holes to transfer heat from the electronics??????

Bill,

The power requirements of the STC-1000 are minimal and shouldn't cause any temperature increase that can't be dissipated through a closed box. The one that I have working now is mounted in the collar of a keezer and gets cooled from the keezer. I had it out in a bench test first and noticed no appreciable heat even when cycling the relays often. A few cubic inches of air space within a triple gang box should be quite sufficient.

 

[cwi]

So, can you replace the probe? Yup, can be done easily and cheaply. Will the probe "work"? Yes it will run the controller. No it's not likely to read accurately over a range of temperatures. How wide a range depends on how accurate you need to be and how close your part happened to be.

Is that the full story? - no. It's enough to give you a pretty good idea of what's going on when you try to do a replacement.

Bob

Why not just buy OEM replacements? They are available on Ebay in both the stainless and rubber versions, 2 for $6 for the rubber ones, I think). They are also available from some stores. The linked store is in the UK, but I have seen them on a few US based sites. It is a very common sensor.

The thermistor inside is a $0.10 part, but finding the correct one, then making it into a probe, probably isn't worth the effort.

 

[carlisle_bob]

Why not just buy OEM replacements? They are available on Ebay in both the stainless and rubber versions, 2 for $6 for the rubber ones, I think). They are also available from some stores. The linked store is in the UK, but I have seen them on a few US based sites. It is a very common sensor.

The thermistor inside is a $0.10 part, but finding the correct one, then making it into a probe, probably isn't worth the effort.

Hi

The gotcha is figuring out *exactly* which part is indeed the replacement. There are literally dozens of "OEM replacements" on eBay. Unless you get lucky, the beta is going to be wrong. Even buying them with the same beta number is a bit of a guess. Different manufacturers come up with different curves for the same beta numbers. To have a drop in / no calibration replacement you need the one that they originally used with the controller.

Bob

 

[emjay]

Let's put it this way. The SS one I bought measures the exact same at 32 and 212 as the one that came with the STC1000

 

[cwi]

Hi

The gotcha is figuring out *exactly* which part is indeed the replacement. There are literally dozens of "OEM replacements" on eBay. Unless you get lucky, the beta is going to be wrong. Even buying them with the same beta number is a bit of a guess. Different manufacturers come up with different curves for the same beta numbers. To have a drop in / no calibration replacement you need the one that they originally used with the controller.

Bob

How about the ones that look *exactly* like the ones that came with it, and are sometimes even sold by the same seller? I have seen both the rubberized and stainless ones sold separately.

Additionally, these controllers are knockoffs, and the sensors they use are certainly the most commonly used NTC thermistor spec. The threaded sensors that Emjay linked have been used successfully by more than a few people. Whether it was dumb luck, or, more likely, a result of most manufacturers of -50C to 200C controllers using the exact same spec for thermistors- the *impossible* work, as you characterize it, has been done, and links provided.

I also highly doubt these controllers are 'batch programmed' to particular runs of sensors, and even less likely that the controller itself is tuned for the batches of all of its internal components. The actual tolerances of discrete parts are much closer than spec sheets portray, especially for a part operating within a very small region of the part's range, like the sensor we are dealing with here.

There is no need to make everything seem so difficult.

 

[Sir Humpsalot]

Sorry for the threadjack.... I was about to pull the trigger on one of these, and then I got to thinking...

$25 STC1000
$7 Extension cord
$10 project box
A pair of $10 GFCI sockets

And I'm within ten or fifteen bucks of the price of a Johnson controller....

Not to dismiss what you all have done. I think it's great, and it looks cool as heck, and I'm a big fan of DIY... I saved some coin by making my stirplate and really enjoy little electrical projects... But I'm thinking that the savings over the Johnson controller isn't all that great when you add it all up. I'm not looking for an argument here, it's just an honest question.

Anybody care to agree or disagree?