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Thermo couple input conditioning
http://forum.diyefi.org/viewtopic.php?f=9&t=740
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Author:  Fred [ Fri Jul 16, 2010 4:59 am ]
Post subject:  Re: Thermo couple input conditioning

It's not that you're not cool enough, probably I'm not cool enough also. It might be down to the file type, or maybe even file system permissions that aren't right at the moment. PM me with the error/message/whatever you got and I'll look into it.

Author:  nitrousnrg [ Mon Jun 20, 2011 10:22 pm ]
Post subject:  Re: Thermo couple input conditioning

A new chip from analog:
http://www.analog.com/static/imported-f ... 6_8497.pdf

It has a 5mV/°C, so with 5v it can reach 1000°C, its enough for the cars I used, but maybe not enough for turbo cars.

Another one is the MAX31855
http://datasheets.maxim-ic.com/en/ds/MAX31855.pdf

It uses SPI and needs 70msec typically to perform a reading, with a 14bit output.

Author:  Fred [ Tue Jun 21, 2011 12:22 am ]
Post subject:  Re: Thermo couple input conditioning

Interesting! Thanks :-)

Author:  russian [ Sun Sep 21, 2014 5:51 pm ]
Post subject:  Re: Thermo couple input conditioning

nitrousnrg wrote:

The only down side of MAX31855 is the price - it's about $4.5 per chip and it's only one channel, so this would multiple if you would want to have four-five channels.

The firmware side of this is trivial: you need a 5MHz SPI and you get a 32 bit packet: 14 bit thermocouple Celsius value, 12 bit chip own Celsius temperature and couple bits for error codes. So yes, you can monitor your ECU temperature for free :)

Author:  ivan141 [ Sun Sep 21, 2014 6:00 pm ]
Post subject:  Re: Thermo couple input conditioning

Since temperature measurements requiring a thermocouple are rarely in-loop control parameters for EFI purposes you could slap in some analog multiplexers and just switch between multiple
input channels to take measurements in a 1 by 1 fashion. Likely to be a much cheaper solution than using multiple MAX31855's, but it does add SW complexity.

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