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have two breakout boards with MAX6675. I have 3 different K-type thermo elements. The MAX is connected to an AVR (atmega8) for communication, driver my own, communicates to PC on UART.

Now none of the combinations of MAX and K-type element works well. The only main feature is that you cannot touch the cable or probe, or even come in vincinity of the cable/probe with my hand without values falling drastically, eventually going to 0 if you take hold of the cable. Also the value drifts substancially when just left alone.

Dont get any grip of whats going on, is the amp oscillating, and then why, what to try for remedy.

Thanks for any help (not allowed to tag with the only useful tag MAX6675)

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  • \$\begingroup\$ The word is 'unstable'. How are you powering the circuit? Have you tried powering from batteries? \$\endgroup\$
    – Kartman
    Apr 23 at 13:05
  • \$\begingroup\$ 1st; onboard 7805 +wallwart12, then tower PC power unit, 5V lead. not tested bat though. strange: The total loss readings when touch, then immediate recover... \$\endgroup\$
    – Georg
    Apr 23 at 15:28
  • \$\begingroup\$ right; slip; "instabil" in swe :) \$\endgroup\$
    – Georg
    Apr 23 at 15:33
  • \$\begingroup\$ well it seems that there are issues,yes Kartman, will try bat, however: forum.arduino.cc/t/max6675-type-k-thermocouple-huge-fluctuation/… doesnt really give much hope "too bad it doesnt work". \$\endgroup\$
    – Georg
    Apr 24 at 10:56
  • \$\begingroup\$ How have you wired the device? How have you validated your 'driver'? Your link was to someone that was doing something silly. \$\endgroup\$
    – Kartman
    Apr 24 at 11:06

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