STC-1000 Temperature Probe BUILD

I Bought a second hand STC-1000 unit a few months back and it did not come with a probe. I could not locate a probe that I could buy and have shipped to my location so with some searching on here and other sites I found the specs for the probe and decided to try building my own. I confirmed yesterday that it works so for your references here are my notes.

The STC-1000 supposedly uses a NTC-MF52AT 10K +-5% 3470 thermistor resistor. Looking at the resistance value chart for this and other resistors I found that the NTC-MF52AT 10K +-5% 3950 looks like it has the same resistance values at different temperatures and should (does) work as well.
Here is a link to an ebay seller for reference of what the resistance chart looks like - I am not endorsing any particular seller.

10k OHM NTC Thermistor Resistor NTC-MF52AT 10K +-5% 3950 +-1%
The thermistors I purchased are 2mm wide and will fit in pretty much any sized tubing you want to use for housing them. - the tighter the fit the better the readings will be of course.

- A friend advised using shielded cable for the sensor wire, however I just used some random wire I had laying around and it worked fine (I used only 1 meter, longer sensor cables probably would benefit from the shielding to reduce noise)
- I just used regular solder to connect the wire to the leads on the thermistor.
- The thermistor was very cheaply purchased from China; about 500 yen (5 bucks) for 2 packs of 10. The same seller is using Aliexpress and Ebay, however there are many sellers for these parts. I chose my seller because they displayed more details and had free shipping internationally (which took 3 weeks to arrive). No customs fees incurred while shipping from China to me in Japan.

So now I have a temp probe for my STC-1000 that works well, for about 30 cents per probe without any housing. It is up to you to figure out housing or waterproofing your own. I will make probes for several pieces of equipment that will be permanently mounted, and just switch out the leads to the controller unit when I need to.

I have no idea how long the probe will last, so if anyone does this and has problems please post!
Cheers,
B

It's been a little while since you posted this.. How are the replacement probes holding up now?

fwiw, I bought a pair of 6' long probes that match the STC-1000 spec here.
They showed up in the mail within the week and I hooked one up and so far it's testing fine.
Not sure that they ship everywhere though

Cheers!

Well, I haven't used them in brewing yet but I have the STC-1000 keeping my chili seedlings at a toasty temp all the time. I have confirmed the temp readings are pretty accurate compared to my handheld digital thermometer, they read within a degree of each other.

I have not focused to much energy on getting pieces and making a waterproof housing for the probe however. I had a stainless probe housing salvaged from scrap metal but it was too narrow to get the thermistor all the way to the end inside, and I had trouble insulating the wires while keeping their profile slim enough to thread inside. I will probably buy a stainless tube from a hobby store, but how to cap the ends nicely to ensure water proofing? The terminal end could be folded over and soldered, but the end with the wires? Rubber foam maybe?

Yeah ebay wasn't an option for me at the time so thats why the alternative build. I still have 19 more thermistors for the price of one from ebay, but the added work of soldering and putting waterproof casing is not really worth it if you only want a single probe. I hope to have several someday.

OppamaBrendan said:

Well, I haven't used them in brewing yet but I have the STC-1000 keeping my chili seedlings at a toasty temp all the time. I have confirmed the temp readings are pretty accurate compared to my handheld digital thermometer, they read within a degree of each other.

I have not focused to much energy on getting pieces and making a waterproof housing for the probe however. I had a stainless probe housing salvaged from scrap metal but it was too narrow to get the thermistor all the way to the end inside, and I had trouble insulating the wires while keeping their profile slim enough to thread inside. I will probably buy a stainless tube from a hobby store, but how to cap the ends nicely to ensure water proofing? The terminal end could be folded over and soldered, but the end with the wires? Rubber foam maybe?

Click to expand...

I would just pack it with some JB Weld and sand it down after it has cured.

OppamaBrendan said:

Yeah ebay wasn't an option for me at the time so thats why the alternative build. I still have 19 more thermistors for the price of one from ebay, but the added work of soldering and putting waterproof casing is not really worth it if you only want a single probe. I hope to have several someday.

Click to expand...

Thanks for the info. I ended up buying a 20 pack of thermistors from eBay from China. They were only three bus so its hard to complain about that. I enjoy little fiddling projects so Ill just make a bunch of homemade probes for myself in case of having another probe **** out on me. Thanks again!

No worries, glad someone got something out of this thread! I picked up the info from various other forums in the past and I wish I could give credit to whoever had listed the specs of the resistor.

Its been a few months using the sensor for chili propagation, and it still is working fine. Now I have it taped to the side of my fermenter and the stc 1000 controlling a heat mat for 17 C.

May I ask why you went with 3950 thermistors instead of getting the 3470's that the STC supposedly uses?

I bought some of these thermistors for my STC-1000: http://www.digikey.com/product-detail/en/NTCLE413E2103F102L/BC2647-ND/2348991

These appear to be working just fine. The sensor that came with the unit was acting up. I bought 5 of them to have some backups.