Report 0-30 Vdc Stabilized Power Supply in Projects Q/A Posted January 5, 2019 On 12/26/2018 at 2:40 AM, audioguru said: The TIP31 is 83 times slower than the BD139 that I recommend that has almost the same speed as the original 2N2219 that got too hot as Q2. Then the TIP31 will probably cause oscillation. I discovered ... The problem has nothing to do with the power supply. I was using a voltmeter based on the ICL 7107 to make the measurements, and when I put another meter I did not find any variation in the output voltages. The readings of my small home-mounted voltmeter go up only when the source has loads on the output, otherwise these metaphysical follies do not happen. When using a common multimeter with a scale of 6,000 counts I did not find any variation in the different loads and voltages that I put in the output of the power supply. Even so, I switched TIP31 to BD139. I am just a hobbyist in electronics and here in Brazil people like me can not afford professional or sophisticated equipment to study and experiment, we need to build our bench equipment by dismantling old appliances and taking advantage of the pieces taken from these scraps. That's why all the information about this project is very important to people like me. Thanks again for the help and information.