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RE: [beam] PS Hbridge question

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  • Wilf Rigter
    No the PS Hbridge is not smokeless! By that I mean if both inputs are high at the same time, high current will flow which can result in loss of the output
    Message 1 of 9 , Oct 30, 2001
      No the PS Hbridge is not smokeless! By that I mean if both inputs are high
      at the same time, high current will flow which can result in loss of the
      output transistors. Unless the input resistor is set to 47K, the PS hbridge
      can be more sensitive to self destructing compared to the original Tilden 6
      transistor h bridge because with a 4.7K input resistor it can deliver more
      current. The PS design reduces current when not needed but tries to supply
      more current under heavy load.

      There are more ways than one to design an h-bridge. It depends on what you
      want to do. Here is a new smoke less design I will call HC-bridge because it
      combines the best features of the H bridge and CMOS motor drivers. It has
      forward, reverse, freewheel and brake modes. The smokeless and brake modes
      can be added to the Tilden h-bridge but makes that design more complicated.

      This HC-bridge circuit may be more suitable for your application but other
      alternatives are available depending on your exact requirements.

      wilf

      -----Original Message-----
      From: Evan Dudzik [mailto:evandude@...]
      Sent: Tuesday, October 30, 2001 12:16 PM
      To: beam@yahoogroups.com
      Subject: [beam] PS Hbridge question


      is your power smart Hbridge smokeless? I want to use
      it on a microcontroller-based robot, and i don't trust
      my programming skills enough yet to avoid "smoking"
      the motor drivers... The reason i don't want to use
      the "smokeless" hbridge you posted recently is that i
      want to convert the bot to a microcore after i figure
      out the walking dynamics, etc. from using the micro,
      and so i can avoid high current drain later on when
      using BEAM brains.

      thanks...

      Evandude

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    • Evan Dudzik
      oh well... i guess i ll have to stick with 74AC245 motor drivers, even though they re kinda expensive compared to just transistors. I dont trust my skills
      Message 2 of 9 , Oct 30, 2001
        oh well... i guess i'll have to stick with 74AC245
        motor drivers, even though they're kinda expensive
        compared to just transistors. I dont trust my skills
        enough yet with programming, and then later with
        microcore stuff to not "smoke" a driver. Is there any
        modification of an Hbridge that is completely
        smokeless, regardless of current draw, IE both inputs
        can be high, and it also won't smoke if one or both
        inputs are left "floating", like if i forgot to set up
        the I/O pin on the micro...

        thanks


        evandude

        --- Wilf Rigter <wilf.rigter@...> wrote:
        > No the PS Hbridge is not smokeless! By that I mean
        > if both inputs are high
        > at the same time, high current will flow which can
        > result in loss of the
        > output transistors. Unless the input resistor is set
        > to 47K, the PS hbridge
        > can be more sensitive to self destructing compared
        > to the original Tilden 6
        > transistor h bridge because with a 4.7K input
        > resistor it can deliver more
        > current. The PS design reduces current when not
        > needed but tries to supply
        > more current under heavy load.
        >
        > There are more ways than one to design an h-bridge.
        > It depends on what you
        > want to do. Here is a new smoke less design I will
        > call HC-bridge because it
        > combines the best features of the H bridge and CMOS
        > motor drivers. It has
        > forward, reverse, freewheel and brake modes. The
        > smokeless and brake modes
        > can be added to the Tilden h-bridge but makes that
        > design more complicated.
        >
        > This HC-bridge circuit may be more suitable for your
        > application but other
        > alternatives are available depending on your exact
        > requirements.
        >
        > wilf
        >
        > -----Original Message-----
        > From: Evan Dudzik [mailto:evandude@...]
        > Sent: Tuesday, October 30, 2001 12:16 PM
        > To: beam@yahoogroups.com
        > Subject: [beam] PS Hbridge question
        >
        >
        > is your power smart Hbridge smokeless? I want to use
        > it on a microcontroller-based robot, and i don't
        > trust
        > my programming skills enough yet to avoid "smoking"
        > the motor drivers... The reason i don't want to use
        > the "smokeless" hbridge you posted recently is that
        > i
        > want to convert the bot to a microcore after i
        > figure
        > out the walking dynamics, etc. from using the micro,
        > and so i can avoid high current drain later on when
        > using BEAM brains.
        >
        > thanks...
        >
        > Evandude
        >
        > __________________________________________________
        > Do You Yahoo!?
        > Make a great connection at Yahoo! Personals.
        > http://personals.yahoo.com
        >
        > To unsubscribe from this group, send an email to:
        > beam-unsubscribe@egroups.com
        >
        >
        >
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        > http://docs.yahoo.com/info/terms/
        >
        >
        >
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        >
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        >
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        >
        >

        > ATTACHMENT part 2 image/gif name=hcBridge.gif



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      • leifwolf@yahoo.com
        what? they re not expensive, they re free! you can get free ac245 s from lots of semiconductor places as free samples, and get all the other chips you need.
        Message 3 of 9 , Oct 30, 2001
          what? they're not expensive, they're free! you can get free ac245's
          from lots of semiconductor places as free samples, and get all the
          other chips you need. and i don't know much about h-bridges, i don't
          do much with them, but the L293 is a nice motor driver if you are
          using larger motors. you can get that free from chip places too. hth,
          e.

          --- In beam@y..., Evan Dudzik <evandude@y...> wrote:
          > oh well... i guess i'll have to stick with 74AC245
          > motor drivers, even though they're kinda expensive
          > compared to just transistors. I dont trust my skills
          > enough yet with programming, and then later with
          > microcore stuff to not "smoke" a driver. Is there any
          > modification of an Hbridge that is completely
          > smokeless, regardless of current draw, IE both inputs
          > can be high, and it also won't smoke if one or both
          > inputs are left "floating", like if i forgot to set up
          > the I/O pin on the micro...
          >
          > thanks
          >
          >
          > evandude
          >
          > --- Wilf Rigter <wilf.rigter@p...> wrote:
          > > No the PS Hbridge is not smokeless! By that I mean
          > > if both inputs are high
          > > at the same time, high current will flow which can
          > > result in loss of the
          > > output transistors. Unless the input resistor is set
          > > to 47K, the PS hbridge
          > > can be more sensitive to self destructing compared
          > > to the original Tilden 6
          > > transistor h bridge because with a 4.7K input
          > > resistor it can deliver more
          > > current. The PS design reduces current when not
          > > needed but tries to supply
          > > more current under heavy load.
          > >
          > > There are more ways than one to design an h-bridge.
          > > It depends on what you
          > > want to do. Here is a new smoke less design I will
          > > call HC-bridge because it
          > > combines the best features of the H bridge and CMOS
          > > motor drivers. It has
          > > forward, reverse, freewheel and brake modes. The
          > > smokeless and brake modes
          > > can be added to the Tilden h-bridge but makes that
          > > design more complicated.
          > >
          > > This HC-bridge circuit may be more suitable for your
          > > application but other
          > > alternatives are available depending on your exact
          > > requirements.
          > >
          > > wilf
          > >
          > > -----Original Message-----
          > > From: Evan Dudzik [mailto:evandude@y...]
          > > Sent: Tuesday, October 30, 2001 12:16 PM
          > > To: beam@y...
          > > Subject: [beam] PS Hbridge question
          > >
          > >
          > > is your power smart Hbridge smokeless? I want to use
          > > it on a microcontroller-based robot, and i don't
          > > trust
          > > my programming skills enough yet to avoid "smoking"
          > > the motor drivers... The reason i don't want to use
          > > the "smokeless" hbridge you posted recently is that
          > > i
          > > want to convert the bot to a microcore after i
          > > figure
          > > out the walking dynamics, etc. from using the micro,
          > > and so i can avoid high current drain later on when
          > > using BEAM brains.
          > >
          > > thanks...
          > >
          > > Evandude
          > >
          > > __________________________________________________
          > > Do You Yahoo!?
          > > Make a great connection at Yahoo! Personals.
          > > http://personals.yahoo.com
          > >
          > > To unsubscribe from this group, send an email to:
          > > beam-unsubscribe@egroups.com
          > >
          > >
          > >
          > > Your use of Yahoo! Groups is subject to
          > > http://docs.yahoo.com/info/terms/
          > >
          > >
          > >
          > > ------------------------ Yahoo! Groups Sponsor
          > >
          > > To unsubscribe from this group, send an email to:
          > > beam-unsubscribe@egroups.com
          > >
          > >
          > >
          > > Your use of Yahoo! Groups is subject to
          > > http://docs.yahoo.com/info/terms/
          > >
          > >
          >
          > > ATTACHMENT part 2 image/gif name=hcBridge.gif
          >
          >
          >
          > __________________________________________________
          > Do You Yahoo!?
          > Make a great connection at Yahoo! Personals.
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        • Wilf Rigter
          ... From: Evan Dudzik [mailto:evandude@yahoo.com] Sent: Tuesday, October 30, 2001 2:05 PM To: beam@yahoogroups.com Subject: RE: [beam] PS Hbridge question Is
          Message 4 of 9 , Oct 30, 2001
            -----Original Message-----
            From: Evan Dudzik [mailto:evandude@...]
            Sent: Tuesday, October 30, 2001 2:05 PM
            To: beam@yahoogroups.com
            Subject: RE: [beam] PS Hbridge question

            Is there any
            modification of an Hbridge that is completely
            smokeless, regardless of current draw, IE both inputs
            can be high, and it also won't smoke if one or both
            inputs are left "floating", like if i forgot to set up
            the I/O pin on the micro...

            thanks


            evandude
            Simple eh?

            wilf


            > -----Original Message-----
            > From: Evan Dudzik [mailto:evandude@...]
            > Sent: Tuesday, October 30, 2001 12:16 PM
            > To: beam@yahoogroups.com
            > Subject: [beam] PS Hbridge question
            >
            >
            > is your power smart Hbridge smokeless? I want to use
            > it on a microcontroller-based robot, and i don't
            > trust
            > my programming skills enough yet to avoid "smoking"
            > the motor drivers... The reason i don't want to use
            > the "smokeless" hbridge you posted recently is that
            > i
            > want to convert the bot to a microcore after i
            > figure
            > out the walking dynamics, etc. from using the micro,
            > and so i can avoid high current drain later on when
            > using BEAM brains.
            >
            > thanks...
            >
            > Evandude
            >
            > __________________________________________________
            > Do You Yahoo!?
            > Make a great connection at Yahoo! Personals.
            > http://personals.yahoo.com
            >
            > To unsubscribe from this group, send an email to:
            > beam-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to
            > http://docs.yahoo.com/info/terms/
            >
            >
            >
            > ------------------------ Yahoo! Groups Sponsor
            >
            > To unsubscribe from this group, send an email to:
            > beam-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to
            > http://docs.yahoo.com/info/terms/
            >
            >

            > ATTACHMENT part 2 image/gif name=hcBridge.gif



            __________________________________________________
            Do You Yahoo!?
            Make a great connection at Yahoo! Personals.
            http://personals.yahoo.com

            To unsubscribe from this group, send an email to:
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          • dkbovaird@aol.com
            Hi Wilf, I m not too good with transistors, but this circuit seems to look a little funny to me. Perhaps you could elaborate on the operation a little more.
            Message 5 of 9 , Oct 30, 2001
              Hi Wilf,

              I'm not too good with transistors, but this circuit seems to look a
              little funny to me. Perhaps you could elaborate on the operation a
              little more. It looks to me like both of the transistors on the same
              side of the motor will be enabled at the same time causing a direct
              short.

              thanks,
              dave.
            • wilf.rigter@powertech.bc.ca
              Your good, Dave! these back of the napkin designs sometimes need a little shakedown from a keen observer before the bugs drop out. That didn t do much for
              Message 6 of 9 , Oct 30, 2001
                Your good, Dave! these back of the napkin designs sometimes need a
                little shakedown from a keen observer before the bugs drop out. That
                didn't do much for smoke free operation (and my appetite). Hope
                nobody fried their transistors cause of my stupid slip of the cursor.

                The corrected schematic is posted here.

                http://solarbotics.net/wilf/PSHbridge/hcBridge1.gif

                wilf


                --- In beam@y..., dkbovaird@a... wrote:
                > Hi Wilf,
                >
                > I'm not too good with transistors, but this circuit seems to look a
                > little funny to me. Perhaps you could elaborate on the operation a
                > little more. It looks to me like both of the transistors on the
                same
                > side of the motor will be enabled at the same time causing a direct
                > short.
                >
                > thanks,
                > dave.
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