I've got an arduino that I built as a standalone, and I'm wondering why is it when a pump status comes on, I get a lot of noise on the temperature sensors. When the pump status point is off, there's no problem?
The pump status input to me is soldered to a PIC pin which switches a relay on / off. The temperature sensors are simple thermistor, resistor divider to input. The ground path is common all ground requirements are soldered back to the one location.