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brown-out issues — Parallax Forums

brown-out issues

ArchiverArchiver Posts: 46,084
edited 2003-07-30 23:36 in General Discussion
so every once in a while my robot decides to brownout? - I think.

Here is the situation: The stamp (BS2) is running the code fine
(blinking two LEDs and then all of the sudden - nothing - the
blinking stops (which is not how I programmed it) and yet the VDC to
the stamp is 6 VDC or better. The code seems to be fine. The robot
includes two other ICs that are H-bridges which are used to control
four electromagnets that sit below all of the circuitry. The
magnets draw .17 Amps @ 6 VDC. The ICs are powered in parallel to
the stamp and each have 47uF capacitors to ground.

I know I may have left some critical details out and that this
problem is really weird - but any help would be much appreciated.

Many thanks,

Paul

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-07-30 21:31
    I had a similar problem with my big robot. Powering all the 5-volt stuff
    including the Stamp with an 1 amp low dropout regulator, it worked fine
    running two motors, a servo and three sensors, but when I added a small DIP
    relay to kill the power to the MotorMind B module, the Stamp would reset
    every time the relay fired. I added a 1000 uF cap across the 5-volt line and
    it works fine now.

    Original Message

    > so every once in a while my robot decides to brownout? - I think.
    >
    > Here is the situation: The stamp (BS2) is running the code fine
    > (blinking two LEDs and then all of the sudden - nothing - the
    > blinking stops (which is not how I programmed it) and yet the VDC to
    > the stamp is 6 VDC or better. The code seems to be fine. The robot
    > includes two other ICs that are H-bridges which are used to control
    > four electromagnets that sit below all of the circuitry. The
    > magnets draw .17 Amps @ 6 VDC. The ICs are powered in parallel to
    > the stamp and each have 47uF capacitors to ground.
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-30 22:49
    Standard cause of this problem: a current surge
    through some motor or other coil type device
    causes the voltage to drop, resetting the
    Stamp.

    6 volts is very close to the Stamp's minimum
    regulation (5.5 volts).

    47 uF is pretty good for decoupling the
    'other chips' -- but 160 mA is a lot of
    current. Does the Stamp have its own
    decoupling capacitor? Is the Stamp on
    the 'far-end' of the power supply from
    the coils? (It's better if the Stamp is
    closer to the supply than the coils).

    --- In basicstamps@yahoogroups.com, "justforgoyourmove" <pjw24@c...>
    wrote:
    > so every once in a while my robot decides to brownout? - I think.
    >
    > Here is the situation: The stamp (BS2) is running the code fine
    > (blinking two LEDs and then all of the sudden - nothing - the
    > blinking stops (which is not how I programmed it) and yet the VDC
    to
    > the stamp is 6 VDC or better. The code seems to be fine. The
    robot
    > includes two other ICs that are H-bridges which are used to control
    > four electromagnets that sit below all of the circuitry. The
    > magnets draw .17 Amps @ 6 VDC. The ICs are powered in parallel to
    > the stamp and each have 47uF capacitors to ground.
    >
    > I know I may have left some critical details out and that this
    > problem is really weird - but any help would be much appreciated.
    >
    > Many thanks,
    >
    > Paul
  • ArchiverArchiver Posts: 46,084
    edited 2003-07-30 23:36
    thanks for your suggestions

    as it turns out the bots were picking up static electricity because
    they were constantly sliding on a plastic surface and by grounding
    them to each other the problem was solved


    regards

    paul

    --- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...>
    wrote:
    > Standard cause of this problem: a current surge
    > through some motor or other coil type device
    > causes the voltage to drop, resetting the
    > Stamp.
    >
    > 6 volts is very close to the Stamp's minimum
    > regulation (5.5 volts).
    >
    > 47 uF is pretty good for decoupling the
    > 'other chips' -- but 160 mA is a lot of
    > current. Does the Stamp have its own
    > decoupling capacitor? Is the Stamp on
    > the 'far-end' of the power supply from
    > the coils? (It's better if the Stamp is
    > closer to the supply than the coils).
    >
    > --- In basicstamps@yahoogroups.com, "justforgoyourmove"
    <pjw24@c...>
    > wrote:
    > > so every once in a while my robot decides to brownout? - I think.
    > >
    > > Here is the situation: The stamp (BS2) is running the code fine
    > > (blinking two LEDs and then all of the sudden - nothing - the
    > > blinking stops (which is not how I programmed it) and yet the
    VDC
    > to
    > > the stamp is 6 VDC or better. The code seems to be fine. The
    > robot
    > > includes two other ICs that are H-bridges which are used to
    control
    > > four electromagnets that sit below all of the circuitry. The
    > > magnets draw .17 Amps @ 6 VDC. The ICs are powered in parallel
    to
    > > the stamp and each have 47uF capacitors to ground.
    > >
    > > I know I may have left some critical details out and that this
    > > problem is really weird - but any help would be much appreciated.
    > >
    > > Many thanks,
    > >
    > > Paul
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