Decent temperature sensor?

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Lurks

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Chaps,

I'm looking for suggestions on a cheap ghetto thermometer sensor that I can use for mashing and sparging. So ideally 1C accuracy in the 60-75C range.

To do this job I knocked up a digital thermometer out of an arduino and bits lying around (pictured), based on DS18B20 sensors. I've used cheap sensor probes off ebay. Allegedly water proof, allegedly good for 125C (the DS18B20 is supposed to be) but the cheapo Chinese probes have cable that's only good to 85 and then they whack heatshrink over the end of the probe which doesn't fill you with confidence. In practice, I've found these probes die after a few brews, always in the 70C range when heating sparge water.

I even bought a proper probe from Adafruit, a DS128B20 in a cable that's good to 125C. Even that died. So at this point I think I'm over the DS18B20.

I'd rather spend almost no money. Ideally I'd like to just use some other sensor into my same mcu+display. That said, looking at thermocouples... an amp chip and a decent probe seems to pretty much go for the same price that you can buy an entire unit for.

Probes are useful because I mash in an unmodified eski and I heat sparge water on the stove. Any suitable ghetto options gratefully received.

mashtemp.jpg
 

JDW81

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Cost wise it is hard to go past a good spirit thermometer. I just leave mine in the MLT and check a few minutes after mash in, then towards the end of the mash to see how the temp has held. I use a round esky and have had no issues with leaving it there for extended periods of time. The only effort required is to open the lid, read quickly then close the lid again. For 12-15 clams it is going to be far more accurate than a cheap digital one. Alternatively invest in an STC-1000 and use that.

JD
 

Lurks

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The STC-1000 is diabolically inaccurate at higher temperatures. (A friend of mine mashed with an STC-1000 and was 5C off, he was not best pleased) Although I suppose I could try work out in what manner it is inaccurate and just compensate. Hmm.

As for spirit jobs. I've got one of those large floaty spirit thermometers. Quite good it is except I've found it's slow to change (it seems to be mounted inside a larger glass tube) and it's hard to flick in the way you would a small spirit job to get it to 'reset'. At the moment I'm using that for my sparge water, figuring that the DS18B20s are less likely to blow up at mash temps...

Dicko, they do look good but it'd only do half of the job (not my sparge water) and for several times more than a sensor. Defo a consideration when knocking up a dedicated mash tun though.
 

Edak

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For highest accuracy you want to use an RTD, but then you will need a data acquisition system (or similar) that has RTD input. If your electronics is uC knowledge is good then you can build a circuit to get you accuracy of 0.1C.

I am surprised that you have had problems with the DS18B20. Perhaps you need one with a suitable thermowell such as the one which I have used for some time now.
 

Lurks

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I actually suspect that the issue is with the sheaf on the cheapo sensors. Eg. they might be potted with something that has a mis-matched thermal expansion and stressing/breaking the actual DS18B20 or the electrical connections. It'd be interesting to cut one open and see.

I did see the one you linked but it's obviously not designed to get through the thick wall of an esky.

I haven't really looked at RTDs. I'll check them out.
 

431neb

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Hey Chinamat,I'm either stupid or clumsy (or both) so I got sick of breaking glass thermometers and bought one of these. It hasn't arrived yet but I'll try to remember to update this thread when I've used it. i'm hoping the probe will be helpful for mashing because reflective surfaces (like wort) are not so easy for the IR one to read.

http://www.ebay.com.au/itm/DIGITAL-INFRARED-LASER-COOKING-THERMOMETER-PROBE-food-glass-oven-kiln-pyrometer/360472746255?ssPageName=WDVW&rd=1&ih=023&category=75601&cmd=ViewItem

Screen Shot 2013-05-06 at 11.17.16 AM.png
 

Lurks

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Heh I hadn't seen one with a probe. I'd really check it against a spirit thermometer though, my experience of thermocouples is that they can be very inaccurate. 3C off and that would make a hell of a difference in a mash...
 

GalBrew

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Why not just get a couple of cheap weldless dial thermometers from eBay or Keg King or wherever? They are piss easy to install (even for a very unhandyman like myself) and will do what you need.
 

GalBrew

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But they are great, they look cool you don't have to dick around with them, they last forever and they are constantly 'on'. I love my dial thermometers, would always have one on each vessel, even with HERMS/PIDs etc.
 

bum

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Will build a computer for a thermometer but a tap to lauter through is a job for later?

sort(priorities);
 

JDW81

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Chinamat said:
As for spirit jobs. I've got one of those large floaty spirit thermometers. Quite good it is except I've found it's slow to change (it seems to be mounted inside a larger glass tube) and it's hard to flick in the way you would a small spirit job to get it to 'reset'. At the moment I'm using that for my sparge water, figuring that the DS18B20s are less likely to blow up at mash temps...
I had one of them and it was shite. Go rid of it ages ago. I just use the standard stick spirit one, and I get my very accurate reading quite quickly. I'll happily sacrifice a few seconds for accuracy, but I'm more of an analogue kind of person. Horses for courses.
 

Lurks

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431neb said:
Hey Chinamat,I'm either stupid or clumsy (or both) so I got sick of breaking glass thermometers
Just noticed the comment about breaking glass thermometers. Heh, for the same reason I now use a refractometer. It got a bit old ordering a new hydrometer with every new batch :)

"Why not just get a couple of cheap weldless dial thermometers from eBay or Keg King or wherever?"

Well yeah. I'm firmly in the land of ghetto solutions right now though, cash strapped student.

"Will build a computer for a thermometer but a tap to lauter through is a job for later?"

One is made out of spare parts lying around. The other requires much more than a tap. Several fairly expensive parts and the destruction of what is my only esky. In fact if I'm doing that I may as well build a recirculating thinggy with temperature control. A job for the next tax cheque perhaps.

"I had one of them and it was shite."

Mm that's good to know. Grab me one for a coupla bucks off ebay me thinks.
 

GalBrew

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I sympathise, having been a student for a LONG time......but...
How much money (including postage) have you wasted on shite that doesn't work? I came to the realisation after wasting a crapload of cash on 'temporary' solutions that ended up being useless to just buy something that is designed to do what you want it to do first time. Saves a lot of time and cash in the long run. Also dial thermometers at KK are $34.95 and as you are in Melb, no postage just pick one up. Or you can get a Mashmaster (for the eski) for $43.95. Or even a clip on dial thermometer for $14.95 (although I would get sick of that fairly quickly).

Ghetto is great, until you add up all the little bits of cash you spent on everything you have tried and realise you should have just done it the easy way off the bat (or just me?)/
 

ivars

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Edak said:
For highest accuracy you want to use an RTD, but then you will need a data acquisition system (or similar) that has RTD input. If your electronics is uC knowledge is good then you can build a circuit to get you accuracy of 0.1C.

I am surprised that you have had problems with the DS18B20. Perhaps you need one with a suitable thermowell such as the one which I have used for some time now.
I've been looking for something similar. Found this on ebay http://goo.gl/wLHnH and was wondering if it would be suitable? Don't quite understand if this is a standalone unit or if it has to be connected to something else. Looks like it doesn't come with a power supply, just a cable to a supply - which is OK. Any thoughts?
 

billygoat

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Hanna Checktemp 1, fast and accurate.
You would have to stretch to around the $50 mark including postage from the US.
Available on ebay.
 

431neb

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431neb said:
Hey Chinamat,I'm either stupid or clumsy (or both) so I got sick of breaking glass thermometers and bought one of these. It hasn't arrived yet but I'll try to remember to update this thread when I've used it. i'm hoping the probe will be helpful for mashing because reflective surfaces (like wort) are not so easy for the IR one to read.

http://www.ebay.com.au/itm/DIGITAL-INFRARED-LASER-COOKING-THERMOMETER-PROBE-food-glass-oven-kiln-pyrometer/360472746255?ssPageName=WDVW&rd=1&ih=023&category=75601&cmd=ViewItem
Chinamat said:
Heh I hadn't seen one with a probe. I'd really check it against a spirit thermometer though, my experience of thermocouples is that they can be very inaccurate. 3C off and that would make a hell of a difference in a mash...
The bloody probe is missing dammit!.

It arrived just now and there aint anything on the business end of the probe lead except a twisted wire. Will update.

WTF? Anyone bought one of these before? Is the probe separate?

Whoa there... I'm going off half cocked. That piece of shit at the end of the two wires is a "Peltier Junction Tip".

I would know that if I had read the information on eBay prior to my purchase. Now what I need is something that I can hang in my mash. Open to suggestions.

PS will check the accuracy of the probe with my...Goddamn it! My fricken thermometer is broken that's why I bought the ....ARhghhhhhh!

Photo on 6-05-13 at 2.49 PM.jpeg


Screen Shot 2013-05-06 at 2.55.06 PM.png
 

Lurks

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ivars said:
I've been looking for something similar. Found this on ebay http://goo.gl/wLHnH and was wondering if it would be suitable? Don't quite understand if this is a standalone unit or if it has to be connected to something else. Looks like it doesn't come with a power supply, just a cable to a supply - which is OK. Any thoughts?
That looks okay. That said, I really don't have a great track record with DS18B20 probes, I've blown up quite a few. Most people seem to get on with them okay. One of the problems with this type of unit is they never tell you what temperatures the cable is actually rated at. Usually it'll be less than 80. Yeah, you just need a 12V supply connected to the lead they give you. It comes with the probe.

"It arrived just now and there aint anything on the business end of the probe lead except a twisted wire."

Heh I love the description where they manage to make the lack of any sort of environmental protection like a stainless steel sheaf sound like a feature. :)
 

431neb

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Chinamat said:
That looks okay. That said, I really don't have a great track record with DS18B20 probes, I've blown up quite a few. Most people seem to get on with them okay. One of the problems with this type of unit is they never tell you what temperatures the cable is actually rated at. Usually it'll be less than 80. Yeah, you just need a 12V supply connected to the lead they give you. It comes with the probe.

"It arrived just now and there aint anything on the business end of the probe lead except a twisted wire."

Heh I love the description where they manage to make the lack of any sort of environmental protection like a stainless steel sheaf sound like a feature. :)
Had a play with it. Seems OK but a longer cable and a probe that I can easily hang in the mash would be good. Assuming it is accurate enough to muddle through one of my not too scientific efforts. I'll email the seller and see if they can help.

Theres no red spot to indicate where it's pointing either. That might be a feature I am yet to discover.

China' is there any reason I couldn't use this probe with the unit I posted before? - Sorry to pester you but you seem to know WTF is going on with these things. - If the plug end doesn't fit can I simply join two wires from the old plug to the new probe and shrink wrap the buggers?


http://www.ebay.com.au/itm/Thermocouple-K-Type-Probe-Sensors-with-connector-2m/251268517204?_trksid=p2045573.m2042&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D27%26meid%3D7461918795495431413%26pid%3D100033%26prg%3D1011%26rk%3D1%26sd%3D251268517204%26


PS there aint no 12 v cable etc.
 

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