high temp thermistor

i was looking at the thermistor i had sourced for the machine, and its only good up to ~125C whereas some of the plastics users might want to experiment with may need to be taken up as high as 200C. i looked around on mouser, trying to find a suitable 10k ohm thermistor, but couldnt find any. i did however find this thermistor that goes up to 250C, but is 100K ohms.

[www.mouser.com]

is this a suitable replacement? what changes would need to be made to the board to take advantage of this thermistor?

Edited 1 time(s). Last edit at 04/27/2007 01:36PM by Zach Hoeken.

Little odd that they don't have a data sheet on that one.

yeah, i agree. they have it for others, but not this one.

got a PM with the datasheet... i love the internet!

[www.gesensing.com] on page 2/8

Great stuff!

That should be OK. Simon's written a guide at

[reprap.org]

The max temperature is governed by two things:

1. Where the device ceases to behave according to its characteristic,
but still works.

2. Where it physically starts to break down (usually because the epoxy
encapsulating it can't stand the heat). Glass bead types can get
pretty hot.

In short, the top limit is the point above which the manufacturer
doesn't guarantee that it will work, but it probably still will...


Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]

Quoting RepRap Forum Mailer :

> Author: ZachHoeken
> Username: ZachHoeken (74.9.71.138)
> Subject: high temp thermistor
> Forum: Developers
> Link: [forums.reprap.org]
> Approved: Yes
>
> i was looking at the thermistor i had sourced for the machine, and
> its only good up to ~125C whereas some of the plastics users might
> want to experiment with may need to be taken up as high as 200C. i
> looked around on mouser, trying to find a suitable 10k ohm
> thermistor, but couldnt find any. i did however find this thermistor
> that goes up to 250C, but is 100K ohms.
>
> is this a suitable replacement? what changes would need to be made
> to the board to take advantage of this thermistor?
> _______________________________________________
> Developers mailing list
> Developers@reprap.org
> [reprap.org]
>



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Well if your going for 10k then you could probably just place 10 of the 100k thermistor in parallel. The problem with this is partly how resistors work, in a sense the lowest resistance will be the resistance that will be seen by the device, so if one of the thermistors is calibrated too low then the reading will be wrong. A better method would be to modify the circuit the thermistor is in. If my guess as to how it is used is right then it's probably part of a resistor divider and all you need to do is just keep the ratios the same and it will work. I'd have to take a look at the schematics to be certain though.

I dont think you realized just how old this thread is, most of this is all completly outdated.