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HomeAircraftHelicopterRadio - JR DMSS › JR Temperature Telemetry Sensor
06-16-2014 11:39 PM  4 years agoPost 21
Four Stroker

rrElite Veteran

Atlanta

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These sensors are usually quite accurate over a wide range. The accuracy exceeds the spec. on the thermisters. I ASSUME that each sensor is individually calibrated so that replacing the thermister alone is not going to get it done.

The only thing I hope to get out of this is for JR to make a more robust sensor. On the other hand, none of mine have broken.

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06-17-2014 12:50 AM  4 years agoPost 22
mpafonseca

rrApprentice

Savannah, GA - USA

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Four Stroker,

I agree with you. I don't really think that this is a good way to do it. I did it just for the sake of learning how it works and to not throw away the interface from my broken sensor. The sensor calibration is exactly the limitation I mentioned before. In order to calibrate the sensor I bought I had to ad a 2k resistance to the circuit, this means that there is no way the resistance will go below that value. So in the original sensor 0k was about the 230 degrees at the end of the scale, now, when the sensor reads 0k the circuit will understand 2k and that corresponds to about 190deg. So I lost usable range from the sensor. For the testing purposes I was doing that is fine. To say that it works like the original, no it don't.
I don't encourage anyone doing that for the actual purpose and expecting precise results. It is just my engineer side wanting to thinker that stuff!! Anyway, it was fun and I wanted to share...

Marco

p.s: I already ordered a new sensor

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06-17-2014 01:49 AM  4 years agoPost 23
Four Stroker

rrElite Veteran

Atlanta

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I used to do stuff like this as well just for fun. I expect that there is an automatic test fixture somewhere that calibrates each sensor through the (servo/bus) plug and programs the chip. I suspect that there is a bias and scale factor programmed. I have stopped now that I can't even see the surface mount parts !

Long ago there were RC specific chips manufactured in small quantities - a few thousands. I am pretty sure that any modern radio does not have a single proprietary chip (programmable chips don't count).

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