Variable Dummy Load for Power Supply Testing. How to test a voltage source to know if it is good or not?. What is the percentage regulation?.

20 Amp Variable Power Supply using LM317

20 Amp Variable Power Supply with an output voltage from 1.5 to 15 volts using the LM317 regulator and 4 2N3055 power transistors to amplify the current capacity

15V power source ON delay using LM317. This circuit uses the LM317 voltage regulator. It also uses a transistor and an a electrolytic capacitor