MK 138 question

Hi VEL417,
I am wanting to use the MK 138 kit in an application that will turn on a 12V fan when the temperature rises above the setpoint and then go off as the temperature falls below the setpoint. Currently the relay and LED energize below the setpoint and turn off above the setpoint. I don’t think it is a good idea for the relay to be energized when the fan is not needed (which is 95% of the time). Can I reverse this operation easily? Maybe swap pins 12 and 13 on the OP amp? Change out the NPN for a PNP T1? Or change the sensor from NTC to PTC? Can you point me in the right direction?

Thanks, Chip.

Swapping the op-amp pins would be the best solution.

Cool, I can do that relatively easily. Thanks for the quick response.


Sorry, I know it’s a daft question, but is it just a case of swapping the connection of pins 12 & 13? (ie 12 to 13 & 13 to 12 & then break the traces).