You can use this calculator to vary the value of the program resistor (R1) and output set resistor (R2) and calculate the output voltage for the LM317 / LM338 / LM350 family of three terminal adjustable regulators. This calculator will work for most voltage regulators with a reference voltage (VREF) of 1.25. Typically, the program resistor (R1) is 240 ohms for the LM117, LM317, LM138 and LM150. For the LM338 and LM350, 120 ohms is typically used. However, other values such as 150 or 220 ohms can also be used. Refer to the adjustable regulator datasheets below for more information.
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