• juerg posted an update 2 years ago

    An error in a script and an unreachable neck position – just burned another HS805BB so badly, it burned a hole into the case and I can still smell the odor of death when entering the house.
    I have added now readjustable fuses for all of my large servos (PFRA 160, Reichelt.de).
    Hope this prevents future smoke!

    • Thats a good idea! Can you share details on how to install them?

      • juerg replied 2 years ago

        Sorry, yes, just route the connection from either plus or minus pole from the power supply to the servo through the fuse. The fuse is supposed to heat up with current flowing through it and increases resistance thereby lowering the voltage for the servo and make it stall. The fuse regenerates when cooling off.
        The fuse works in a slow mode so normal movements will not trigger it . I haven’t had the courage to run a full test with a blocked servo so – as it might be the right path – I am not totally sure whether it will protect a HS805BB in all cases or limit the servos performance unnecessarily. The fuses come in different strenght’s so a member with more electronic knowledge may point us to a better suited part then the PFRA 160.

        • Thanks juerg, I’ll check into it more as well.

          • mmm good idea, i add too some capacitors to prevent jitter ( i test it tonigh ) : http://letsmakerobots.com/node/12679

            • juerg replied 2 years ago

              let me know about your caps result. I had an issue with a digital servo impacting another analog one. After connecting the dig servo to another power distribution point the problem resolved itself but having a cap for the signal lines looks to me like a more robust solution

            • I think we have the same problem, I have mixed dig cys and analog 805bb. I tell you the results soon

      • juerg replied 2 years ago

        Update: Actually had a problem with left shoulder rotation servo (continuing small repositiong with growl) and after a while it stopped to move (fuse and servo rather hot) so the fuse did it’s job.
        Have added now the 104 (100nF) caps for all shoulder servos (between signal and ground) and as it did not completely stop the growl a lot of has gone with that update.
        Thanks Antony for the cap’s recommendation

    • Juerg I just want to say : IT’S MAGICAL :) . No more jitter or zombie servo when detach : https://www.facebook.com/photo.php?fbid=10210323785361860&set=p.10210323785361860&type=3&theater

      • juerg replied 2 years ago

        thanks, great picture but I do not use nervo boards.
        the pin right next to e.g. 12 is the signal line?
        the dark green edged pins are the + power ones?
        the 100uF ground side is on the signal?
        and 104 is a 100 nF cap?

        • the 100uF ( the big chimical, it’s bad we need ceramic ) is pluged to +6v ground power line .
          The 100nF ( The small 104 ceramic ) is pluged to each signal pin. ( +signal , ground )
          The signal and the power shared the same ground.

          • Great! I remember a post on the InMoov forum mentionning something similar, It sure would be great to add that option on the next Nervo boards release.