Welcome to the TT Electronics On Line Input Resistors product training module. This presentation will be looking at the definition and functions of a line input resistor in a power supply circuit. The engineer will look at how the requirements of this application are sometimes contradictory, and why careful choice of resistor technology is essential. Then, the engineer will review the key TT electronics products available for line input designs and some design tools that will help the customer in one’s power supply design.