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12584Re: Power Supply Tricks? Final analysis

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  • pjc309430 <pjc30943@isic.org>
    Jan 7, 2003
      Hi Kip,

      Thanks for your reply. I _do_ have the headroom for the drop, and
      tried your idea.
      There was some improvement over some other approaches (namely, not
      all the PICs reset), but the bx24s unfortunately still restarted.

      Sorry for the late reply, I was out of town (and out of email) for
      a few days.


      Now to all others who had responded:
      Thanks for the assistance, with these tips my next supply will be
      more robust. Fido still operates fine so far, so luckily headway is
      not impeded with this phenomena. The easiest--but for now
      unfortunately also a sort of "give-up" way--is to add another
      switching regulator at the same voltage as the motors; using a
      standard seperate regulator seemed to cure the problem.
      So this is the way I'll go.

      [Of course any suggestions are still welcome.]

      Thanks for the help,
      Paul






      --- In SeattleRobotics@yahoogroups.com, "Kipton Moravec" <kip@k...>
      wrote:
      > I have one last thing for you to try. On the power supply to the
      > microcontroller put a diode between the battery and the big
      capacitor on the
      > input of that one power supply.
      >
      > If the motor is sucking up too much current, the capacitor will
      hold the
      > voltage up for the processor since it will not be able to discharge
      because
      > of the diode. Of course this assumes you have the head room for
      the .6 V
      > diode.
      >
      > Finally another kluge you can try. Assuming you have at least 12V
      for your
      > 5V regulator, Put a diode between your main batteries and the
      input
      > capacitor for the 5V regulator (as above). In parallel put a 9V
      transistor
      > battery with a diode to the same input capacitor for the 5 V
      regulator
      > capacitor. If the input voltage falls below about 8.4V, the 9V
      battery
      > kicks in for the 50ms or so until the 12V battery recovers.
      >
      > Kip
      >
      > ----- Original Message -----
      > From: <pjc30943@i...>
      > To: <SeattleRobotics@yahoogroups.com>
      > Sent: Tuesday, December 31, 2002 6:42 PM
      > Subject: [SeattleRobotics] Re: Power Supply Tricks?
      >
      >
      > > Hi Paul,
      > >
      > > Thanks for the reply.
      > > My driver is controlled by a serial stream.
      > > Interesting thought about the switch. It led me to think about
      > > whether the switch was arcing (significantly) as I closed it,
      causing
      > > all sorts of interference. But I don't think that this is the
      case,
      > > after more examination.
      > >
      > > But good idea, I'll keep it in mind for the future.
      > > Thank you,
      > > Paul
      > >
      > >
      > > --- In SeattleRobotics@yahoogroups.com, "Paul Davis"
      <youhere@h...>
      > > wrote:
      > > > Do you have the appropriate pull up/down resistors on the
      control
      > > lines to
      > > > motor drivers? Maybe while the processors are in reset they are
      > > floating or
      > > > at the wrong value causing shorts and other whacky stuff,
      causing
      > > the power
      > > > to sag in the rest of the robot or at least drain those large
      caps
      > > and
      > > > causing the charging problem already mentioned.
      > > >
      > > > Paul Davis
      > > >
      > > > >After original powerup, even with motors running, there are no
      > > resets.
      > > > >Only when they are turned off and on again during operation
      (i.e.,
      > > the
      > > > >glitch occurs in the beginning before the micros are fully on,
      so
      > > they
      > > > >don't notice).
      > > >
      > > >
      > > >
      > > >
      > > >
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