Fake Thermistor

General discussion of 3D printers

Fake Thermistor

Postby bdring » Thu Nov 29, 2012 3:14 pm

A quick way to help debug thermistor issues is to use a fixed resistor right at the controller. Use a small resistor with a resistance equal to the room temp value of your thermistor.

I did this last night at the Hackerspace. I did not have my extruder installed, but wanted to run the motors. Pronterface was complaining about the open themistor circuit. Rather than hack the code, I just screwed a 100k resistor into the terminal block for the thermistor connection. Everything was happy and I was even able to verify the 'temp'.
Bart
"If you didn't build it, you will never own it."
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Re: Fake Thermistor

Postby orcinus » Thu Nov 29, 2012 4:36 pm

The first thing that occurred to me when i read the subject was "wow, they're counterfeiting thermistors now too?" :lol:

I'll blame it on lack of sleep and coffee.
Incidentally, i remember an ATmega328 post-mortem posted somewhere (Adafruit?) which ended up revealing a solid copper slug inside the chip package where the die should have been.
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Re: Fake Thermistor

Postby cvoinescu » Thu Nov 29, 2012 9:06 pm

But copper is expensive!
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Re: Fake Thermistor

Postby orcinus » Thu Nov 29, 2012 11:00 pm

Yeah, that was the bizarre part.

Edit: Found it! It was SparkFun: http://www.sparkfun.com/news/350 Although i'm sure someone else had a similar post-mortem too.
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