Recent content by ffrige

  1. ffrige

    LM317 Variable power supply

    Thanks a lot guys. I now put two diodes in parallel, just to make sure that nothing bad happens again...
  2. ffrige

    LM317 Variable power supply

    So... I finally managed to finish my variable power supply, but unfortunately it didn't last long. I used it to drive a DC motor and, as you guys suggested, I simply reversed the output wires to change direction. After just a few switchings the LM317 croaked. I imagine some inductive spikes from...
  3. ffrige

    LM317 Variable power supply

    MP, thanks for the answer and sorry if I was confusing. I guess I didn't want to use two different regulators since I don't need positive and negative voltage at the same time. But I need a switch to be able to flip the output somehow. If I can't do that with the ac voltage using only one...
  4. ffrige

    LM317 Variable power supply

    Hi everyone! I saw there are several different projects for power supplies and I'm not sure what the real differences between them are. In particular, what is the difference between using a high current regulator (say lm317 or lm350) and using a low current one (lm723) with external transistors...
  5. ffrige

    negative impedances

    Hi. I ran into the problem of subtracting two impedances. I thought I could solve it simply by putting the first in series with the negation of the second (using a negative impedance converter), but something is not working. Is it really possible, for example, to put a resistance in series with...
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