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Double trouble

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  • farrierno1
    OK guys, I have sorted the leg problem with my walker(used springs!!) now I have a problem with the reverser. I used the ACW circuit and 74HC245 driver. Will
    Message 1 of 6 , Jul 25, 2002
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      OK guys, I have sorted the leg problem with my walker(used springs!!)
      now I have a problem with the reverser.

      I used the ACW circuit and 74HC245 driver. Will the reverse work
      with this driver or do I need to use the 240 configured as a
      reversible driver? Im probably being thick but it doesn't seem to be
      made clear in any other designs I have looked at.

      The second thing: is there any way of increasing the trigger voltage
      of a 1381?. An "L" is the largest I have at the moment and it will
      be some time before I need to place an order big enough to justify
      the delivery charge!!
    • Bruce Robinson
      ... You can t build a reverser with a 245 chip alone. The 245 is a non-inverting driver; the typical driver-dhip reverser requires (A) a pair of inverters,
      Message 2 of 6 , Jul 25, 2002
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        farrierno1 wrote:
        >
        > OK guys, I have sorted the leg problem with my walker(used springs!!)
        > now I have a problem with the reverser.
        >
        > I used the ACW circuit and 74HC245 driver. Will the reverse work
        > with this driver or do I need to use the 240 configured as a
        > reversible driver? Im probably being thick but it doesn't seem to be
        > made clear in any other designs I have looked at.

        You can't build a reverser with a '245 chip alone. The '245 is a
        non-inverting driver; the typical driver-dhip reverser requires (A) a
        pair of inverters, and (B) an enable line.

        Bruce
      • Dave Hrynkiw
        ... Sure you can. Run a 47k shunt resistor from the input to the opposite ADJACENT output, so when you enable the chip, the buffer over-rides the 47k signal
        Message 3 of 6 , Jul 25, 2002
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          At 09:48 AM 07/25/02, Bruce Robinson wrote:
          >You can't build a reverser with a '245 chip alone. The '245 is a
          >non-inverting driver; the typical driver-dhip reverser requires (A) a
          >pair of inverters, and (B) an enable line.

          Sure you can.

          Run a 47k shunt resistor from the input to the opposite ADJACENT output, so
          when you enable the chip, the buffer over-rides the 47k signal with the
          other channel.

          Input 'A' --> 47k --> output 'B'
          Input 'B' --> 47k --> output 'A'

          Turn the chip on (with the enables), and:
          Input 'A' --> (buffer overpowers 47k signal) --> output 'A'
          Input 'B' --> (buffer overpowers 47k signal) --> output 'B'

          So technically, you're right; you need a pair of resistors too! ;->

          Later,
          Dave
          ---------------------------------------------------------------
          "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
          that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
          2 vowels. Pronounciation? _SMITH_".
          http://www.solarbotics.com
        • Bruce Robinson
          ... Of course! Thank s Dave. I was thinking inside the box (hate it when that happens). Bruce
          Message 4 of 6 , Jul 25, 2002
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            Dave Hrynkiw wrote:
            >
            > At 09:48 AM 07/25/02, Bruce Robinson wrote:
            >> You can't build a reverser with a '245 chip alone. The '245 is a
            >> non-inverting driver; the typical driver-dhip reverser requires (A) a
            >> pair of inverters, and (B) an enable line.
            >
            > Sure you can.
            >
            > Run a 47k shunt resistor from the input to the opposite ADJACENT
            > output, so when you enable the chip, the buffer over-rides the 47k
            > signal with the other channel.

            Of course!

            Thank's Dave. I was thinking "inside" the box (hate it when that
            happens).

            Bruce
          • sebastiaan van Vliet
            but you trash the buffering capabilities of a 245 to drive motors... ... _ _ /|о| |о| // ¯ ≡≡≡≡≡≡≡≡//¯ See the
            Message 5 of 6 , Jul 25, 2002
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              but you trash the buffering capabilities of a 245 to drive motors...


              >From: Bruce Robinson <Bruce_Robinson@...>
              >Reply-To: beam@yahoogroups.com
              >To: beam@yahoogroups.com
              >Subject: Re: [beam] Double trouble
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              >farrierno1 wrote:
              > >
              > > OK guys, I have sorted the leg problem with my walker(used springs!!)
              > > now I have a problem with the reverser.
              > >
              > > I used the ACW circuit and 74HC245 driver. Will the reverse work
              > > with this driver or do I need to use the 240 configured as a
              > > reversible driver? Im probably being thick but it doesn't seem to be
              > > made clear in any other designs I have looked at.
              >
              >You can't build a reverser with a '245 chip alone. The '245 is a
              >non-inverting driver; the typical driver-dhip reverser requires (A) a
              >pair of inverters, and (B) an enable line.
              >
              >Bruce




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            • Dave Hrynkiw
              ... Yup. Good point. Well, what s one more chip? ; ... Um, no - that s H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes, that s right. Yes, I know it looks like
              Message 6 of 6 , Jul 25, 2002
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                At 03:41 PM 07/25/02, sebastiaan van Vliet wrote:
                >but you trash the buffering capabilities of a 245 to drive motors...

                Yup. Good point. Well, what's one more chip? ;>

                ---------------------------------------------------------------
                "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
                that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
                2 vowels. Pronounciation? _SMITH_".
                http://www.solarbotics.com
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