OctoPROBER. The 8-Channel Temperature Logger!

Schematic

This has been an idea I have been kicking around for awhile. The OctoPROBER is a 8 channel, K-type thermocouple temperature logger. It has a micro SD card slot for logging data remotely. The USB connection can send log data directly to the PC.

Power is supplied via internal lithium 18650 3.7V cell and is charged over USB. The BQ24075RGTT is used to manage the charging of the lithium battery by using the outputs of the FT230X USB chip. I will cover this in more detail when I can verify my idea will work.

To prevent corruption of the SD card a soft power circuit is employed. A single optocoupled output is given to allow control of an external circuit.

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6 thoughts on “OctoPROBER. The 8-Channel Temperature Logger!”

  1. This looks good. Hopefully I can keep updated on this. Would like something like this. Have you considered precision timing associated with the logging? Something similar to picpet (http://www.leapsecond.com/pic/picpet.htm). This would allow people that have precision 10MHz references very precise timing of the logged temperatures. Just a thought.

    Bill

  2. Awesome. I actually built something like this using the SF easy logger with SD card. That device can enumerate the card as a thumb driver. It makes life a lot easier if you can charge and dump the data at the same time. A bit of warning. the op amps I used were insanely sensitive to noise. I proved it by doing a baseline of the unit in and out of a shielded esd bag. At the end of the day I simple put the entire fixture into a aluminum Hammond box and threw a ferrite with 3 turns to clean up the noise coupled from the thermocouple.

    1. I will keep that in mind. Might put the footprint on the prototype board just in case I need a ferrite bead.

      I am using the MAX31855K with 0.01uF ceramic cap across the thermocouple leads so I hope that is enough to reduce the noise.

  3. This is an awesome idea. I have a wood fired bread oven with type-K Thermocouples embedded in the dome and hearth and have been using a hand held meter to monitor temperatures. I would like to log the temp data to see what my heating and cooling curves look like and I have been playing around with various separate components etc. I would like to build a simple logger to capture the data. Please keep the information coming on how this is working.
    Thanks
    John

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