Meat thermometer, what kind of sensor is in there?

Why not use a thermocouple? They're reliable and many low-price DVMs have thermocouple inputs.

Den tirsdag den 20. december 2016 kl. 00.11.15 UTC+1 skrev Joerg:

I just measured one I have here, it looks just like a standard 10K NTC

I don't know, they always come with the sensors. Have to, because it's a heat-proof assembly. Such a sensor with a thermocouple in it costs about as much as the whole enchilada with radio and display unit.

Thanks, Lasse. Should be the same here because they all come from the same place, China. I guess then my sensor is busted because it should not measure different resistance in either direction. It's also erratic.

Seems nobody wants to sell individual probes. It has a phono plug but if it breaks that's no use.

What did those Trappist monks use?

mini has minijack, like this:

I don't see why a thermocouple should cost that much. If it used noble metals then yes but your common or garden k-type is made from cheap alloys.

not exactly expensive

Probably you'd have to join the convent for a few years, or decades, to find out.

It's mainly to bring up the pot to temperature while doing something else. When it gets to 155F it warns me and I can walk down there, turn the burners off and start steeping. The temps for mash and steep are critical. A 5-10F error can spoil a whole batch and you won't find out before bottling, meaning lots of time sunk into it. Afterwards I set it to 206F so I get a warning before a boi-over happens. Those are very messy with wort because it's essentially all sugars leeched out of grains.

Since I want to be able to brew inside all I've got is two 1kW cooktop burners connected to two different circuits and things take forever. Need to be able to work in the office during heating phases without risking a mess.

That plug looks like it fit. Quite pricey though, you can almost get a whole thermometer with the electronics.

However, for boiling purposes one needs a probe which is metal-shielded and can be scrubbed. With a heat-resistant cable that can also be scrubbed. The wort being cooked when making beer becomes almost as sticky as chewing gum when residue of it cools.

you have a multimeter that understands thermocouples?

They produce a much lower voltage change per unit temperature change than a properly biased thermistor or a semiconductor sensor, which makes the read out electronics more expensive (one way or another). And it's hard to desig n connections that don't introduce extra thermocouple junctions into the si gnal path. With a thermistor you can alternate the excitation to get the ex tra thermocouple voltages to cancel out (if you need to).

Stick it inside a stainless tube.

Try AliExpress.

Dan

Some 10k thermistors and a lab jack?

George H.

Yes, I don't see much difference between waterproofing a thermistor or a thermocouple.

I would have thought a thermocouple sensor would be cheaper given it's simply two spot-welded wires.

Are there any common thermistors that will take that sort of heat?

Common thermistors tend to stop at 150C, but Newark thinks it lists 32 parts that can survive 300C. Many of them seem to go to 302F, which isn't quite right but here's one that can do 300C

There are 400 of them in stock for $6.64 each in small quantities.

is a more classical package, cheaper at $1.27, and they have 187 in stock.

Glass encapsulated thermistors can survive fairly high temperatures - you have to melt the glass before you can get it to encapsulate the thermistor. Long term stability at high temperature may not be wonderful.