Thermistor

Transistor... Thermistor...

These are found in various places such as:

• Input current limiting (beginning of switching power supplies)
• Temperature Sensors (3d printer beds, lithium batteries)
• Temperature cutoffs (coffee maker)

Tips/Techniques

Checking an Input Current Limiter is Working

Use hot air, and the resistance should increase. This alternatively is a way to detect if what you are looking at is a thermistor. For: Identify this chip.