Hello friends! Today we will work through the LM317 calculator and learn how to choose the resistors for an adjustable power supply. We will start with the basic circuit, calculate an output voltage, and then work backward from a voltage we want to obtain. The resistor calculation is only one part of the design. A regulator also needs enough input voltage, a suitable load and a way to release the heat it produces. Understanding those conditions will help you avoid a circuit that looks correct in a calculator but gives an unexpected reading on the bench. If you are new to this device, read our Introduction to LM317 alongside this tutorial. Here, we will concentrate on the calculations and the decisions you can make from them. Figure: LM317 adjustable regulator circuit and resistor positions ...