Stc-1000 wiring

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Revvy said:
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.
Click to expand...

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
 
carlisle_bob said:
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
Click to expand...

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.
 
JuanMoore said:
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.
Click to expand...

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
 
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!

:mug:
 
carlisle_bob said:
Hi

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

Bob
Click to expand...

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

Stauffbier said:
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!

:mug:
Click to expand...

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

View attachment 71775
Click to expand...


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).

7985165811_2002e67138.jpg
 
pjcampbell said:
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).

7985165811_2002e67138.jpg
Click to expand...

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

You're right, I was looking at the probe temperature range for operation, not the rating for the unit itself.
 
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.
 
pjcampbell said:
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.
Click to expand...


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.


Tctrl2.jpg
 
pjcampbell said:
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).
Click to expand...

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.

image-2382571736.jpg

Here is a picture of it apart.
 
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??????
 
HbgBill said:
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??????
Click to expand...

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.
 
carlisle_bob said:
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
Click to expand...
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.
 
cwi said:
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.
Click to expand...

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
 
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
 
carlisle_bob said:
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
Click to expand...
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.
 
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?
 
Sir Humpsalot said:
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?
Click to expand...

The johnson is only single stage, the STC-1000 is dual stage. The johnson is also analog with no compressor delay and no way to change/adjust the temp differential. The cost is similar, but the STC-1000 has a lot more features and functionality. Nothing wrong with the johnson controller, especially for a keezer or other applications that only require single stage control, but it's not really a comparable product. A better comparison would be a ranco dual stage controller, which runs ~$120 IIRC

And FWIW it can be put together significantly cheaper than the price list you have there.
 
JuanMoore said:
The johnson is only single stage, the STC-1000 is dual stage. The johnson is also analog with no compressor delay and no way to change/adjust the temp differential. The cost is similar, but the STC-1000 has a lot more features and functionality. Nothing wrong with the johnson controller, especially for a keezer or other applications that only require single stage control, but it's not really a comparable product. A better comparison would be a ranco dual stage controller, which runs ~$120 IIRC

And FWIW it can be put together significantly cheaper than the price list you have there.
Click to expand...

All of this^

Plus you can mount the stc-1000 in your collar and it looks cool!
 
So I have been reading these wiring threads for a bit and I am a little confused. I am only going to be using the STC-1000 for cooling. Basicly the controller just applies or removed power from the socket you will have you freezer plugged into right? If so would this simple diagram work?

I havent looked at the STC for a bit but I assume hot and neutral go to it on pins 1 and 2.... or is 2 a ground
 
Nevermind. I think I went full retard for a second. Pins 7 and 8 are hot in and hot out respectivly. So the neutral would come right off the plug right? Like this

232323232%7Ffp635%3A5%3Enu%3D5664%3E252%3E25%3A%3EWSNRCG%3D3574%3A6358534%3Bnu0mrj
 
trent_77590 said:
Nevermind. I think I went full retard for a second. Pins 7 and 8 are hot in and hot out respectivly. So the neutral would come right off the plug right? Like this

232323232%7Ffp635%3A5%3Enu%3D5664%3E252%3E25%3A%3EWSNRCG%3D3574%3A6358534%3Bnu0mrj
Click to expand...

This one is correct, except the hot and neutral connections to the receptacle should be reversed with it facing as shown. When looking at the front of the receptacle the neutral is on the left and the hot is on the right.
 
Sir Humpsalot said:
$25 STC1000
$7 Extension cord
$10 project box
A pair of $10 GFCI sockets

Anybody care to agree or disagree?
Click to expand...

You can get the STC-1000 for $23

I use the 16/3 cord so I have a ground there $10

Romex boxes are cheaper, but the box I use is nearly $9 with the fancy cover plate.

Why do you need a pair of GFCIs? I use one standard outlet at $3

I'm at $45 vs your $62 and it can be done a few bucks cheaper with less pretty parts.
 
I have both a Johnson and the STC-1000 now. I like the STC-1000 better. My biggest beef with the Johnson controller is that to change the temperature setpoint, you have to press the up or down button once for each degree. You can't just hold the button down and let it scroll to the setting you want. So that is a real pain when wanting to change between say 75F or keeping something warm to 195F for broth making and then back again, pressing that @&$!@ button 120 times each way is reallllllyyy irritating.

I used a Yellow Jacket 14/3 extension cord I got for $14 from Lowes, a 3 gang box, and bought a 10 pack of decora outlets since I'm going to make two of these beauties. I debated on the GFCI and went without it, I just don't like them in refrigeration applications. They're not supposed to trip falsely but there many people seem to have trouble with nuisance tripping when used with refrigerators and freezers.

The Johnson does have a temperature differential, at least mine does, in the settings. But right, it's just a single relay contact. You could wire up heat of the NC contact and cool off the NO contact but it would be always running heat or cold then, no condition where it's neither heating nor cooling.
 
This may have been discussed?? I just received my STC-1000 yesterday. Nice looking unit.

Question is: How much of a load can this handle on 110vac? The instructions say it's 10A @ 250vac for both heating and cooling. What does that translate to @ 110/120vac?

Thanks, Bill
 
Revvy said:
I noticed you subscribed to two threads I posted my diagram in. Do you have any specific questions.
Click to expand...

Yep, now I do.. I like the schematics both you and JuanM posted. I'd really like to combine the two. IOW, Have the controller fed from a non-controlled duplex like you/Revvy has.. so the duplex is not tied up.. then only have one duplex on the output side like JM's but have half of the controlled duplex for heating and the other half for cooling.

I think I understand how to do it.. but, great graphics are a real aid to a retard like me.
 
HbgBill said:
This may have been discussed?? I just received my STC-1000 yesterday. Nice looking unit.

Question is: How much of a load can this handle on 110vac? The instructions say it's 10A @ 250vac for both heating and cooling. What does that translate to @ 110/120vac?

Thanks, Bill
Click to expand...

It sounds like they might have accidentally sent you a 220V unit instead of a 110V unit like they did to me.... I had to contact the shipper and get them to send me the 110V.
 
HbgBill said:
Question is: How much of a load can this handle on 110vac? The instructions say it's 10A @ 250vac for both heating and cooling. What does that translate to @ 110/120vac?

Thanks, Bill
Click to expand...
If it is rated for 10A @ 250VAC, it will handle at least 10A at 110VAC. If you take off the controller housing, you can look at the relays themselves to see what they are rated for. (Although, I have seen some funky numbers on Chinese parts.) Either way, 10A is more than enough for any compressor or heat source for fermenting/serving. Any other application, like an E-brewing vessel, should use an SSR controlled by the relay in the STC-1000. However, for E-brewing, a better choice is a cheap PID with built in SSR output.
 
HbgBill said:
This may have been discussed?? I just received my STC-1000 yesterday. Nice looking unit.

Question is: How much of a load can this handle on 110vac? The instructions say it's 10A @ 250vac for both heating and cooling. What does that translate to @ 110/120vac?

Thanks, Bill
Click to expand...

Being the inquisitive sort, I opened up an STC-1000 110v unit. The relays inside are marked 12vdc-1hs for the coil and 10A 277VAC, 15A 125VAC for the contacts. Leads me to a couple of conclusions.

1) at 120V a 15A load is acceptable
2) the relays may be removed and the coil signal output to an SSR for higher loads.

I'll test #2 shortly, as I want to switch a larger load on a non-brewery application.
 
HbgBill said:
Don't know how to tell.. the outside of the box says 110v
Click to expand...

My box also said 110v. As helibrewer mentioned, the schematic sticker on the unit will show either 110v or 220v at the AC connection point. Or you can go the route of opening it and looking at the transformer or relays as mentioned above. I believe both are rated at 10A. I still have the 220v unit that they sent. They said I could keep it if I paid five additional dollars to ship the 110v. So I ended up getting both units for $28. I found a thread on this forum that expalins how to convert the 220v over to 110v. I'll link it if you need it...
 
Thanks guys, my controller says 110v.. but the instructions are what have the 10A@250vac. My understanding was that the amperage is what drives things. For instance.. in cars of yesteryear, we had 6vdc systems. The wires were "huge" compared to the 12vdc systems in cars of the same vintage. Everything about a 6v system was beefier. I would think, intuitively, that the ratings for a 10A@250vac would be about 1/2 the rating.. but, I'm not an E engineer.
 
ChuckO said:
Being the inquisitive sort, I opened up an STC-1000 110v unit. The relays inside are marked 12vdc-1hs for the coil and 10A 277VAC, 15A 125VAC for the contacts. Leads me to a couple of conclusions.

1) at 120V a 15A load is acceptable
Click to expand...
I would consider a 15A load pushing it. Staying within ~80% seems more prudent.

ChuckO said:
2) the relays may be removed and the coil signal output to an SSR for higher loads.
Click to expand...
There is no need to remove the relays to use an SSR, just use the relay to switch a 12V wall wart. For a permanent SSR solution, a cheap (~$35) PID controller with PID, on/off, and manual control (% On) make more sense, unless you already have an extra STC-1000 you will never use for anything else.
 
HbgBill said:
I would think, intuitively, that the ratings for a 10A@250vac would be about 1/2 the rating.. but, I'm not an E engineer.
Click to expand...
The ratings on the relays themselves are a bit dubious. Generally, relays are limited, separately, by a voltage and a current. The relays in these units have different current rating for 220VAC and 110VAC. Those ratings seem to be related more closely to typical max household circuit breaker size in the US and EU, than any engineering analysis of the relays.
 

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