Why is there electrical noise on the device I’m trying to temperature control?
Many temperature controlled devices are electronic components capable of picking up electrical noise. Since the sensor and TEC are typically located near the load, they can radiate noise onto the device being cooled. Ferrite beads and filter capacitors can be added to the thermistor and TEC leads to minimize radiation effects, and shielded cables should be used. Temperature controllers operated from switching power supplies radiate noise at the switching frequency.