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Re: [beam] Re: 555 for a voltage sensor in a SE

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  • Wilf Rigter
    Hi Johnny , any photodiodes will work. The trigger level is about 3 times the photo voltaic output of the PD. Add a series Si diode to raise the trigger level
    Message 1 of 4 , Mar 14, 2003
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      Hi Johnny ,

      any photodiodes will work. The trigger level is about 3 times the photo
      voltaic output of the PD. Add a series Si diode to raise the trigger level
      by 300mV (3x 100mV) . Since the PD voltage rises with the log of the light
      level this means the PD voltage changes little over a large light range
      making the trigger level and the "pop" relatively constant. The 555 with
      the PD with the lower output voltage will of course trigger first. The cap
      should be sized to cause the motor to turn the bot no more than 45 degrees
      each pop. Any larger cap and the bot does "twirls".


      However your question "triggered" a new version that can use larger caps for
      longer pops by driving both motors at the same time but with a turning bias,
      which depends on the side triggered.
      As shown in the attached, the two diodes connect an active low output which
      drives a primary motor directly, also to the opposite motor. The diode drop
      reduces the voltage applied to the secondary motor so that it turns more
      slowly than the primary motor.

      regards

      wilf


      ----- Original Message -----
      From: "Johnny Flores" <jflores6@...>
      To: "Wilf Rigter" <Wilf.Rigter@...>; <beam@yahoogroups.com>
      Sent: Wednesday, March 12, 2003 1:45 PM
      Subject: [beam] Re: 555 for a voltage sensor in a SE


      Looks cool! Are the diodes marked "PD" standard photodiodes or something
      else? Any specific part number? Also, I'm assuming that a larger cap
      (e.g., 6800uF) would cause a longer charge time but also a longer discharge
      time?

      Thanks again!

      Johnny
      ----- Original Message -----
      From: Wilf Rigter
      To: 'J Flores'
      Sent: Wednesday, March 12, 2003 12:04 PM
      Subject: RE: 555 for a voltage sensor in a SE


      oops, try this for that 555 article.

      http://groups.yahoo.com/group/beam/message/24457
      -----Original Message-----
      From: J Flores [mailto:jflores6@...]
      Sent: Wednesday, March 12, 2003 7:28 AM
      To: Wilf.Rigter@...
      Subject: 555 for a voltage sensor in a SE


      I read a "letter to the editors" in the current issue of Nuts and Volts
      that described the use of a 555 chip as part of a voltage sensing circuit in
      a battery charger. It was set up with a voltage divider across the input
      and trigger pins (3 and 6?) such that when the power available from the
      battery dropped to a preset threshold, the 555 triggered a solid state relay
      to turn on the charger.

      I'm wondering if a similar (albeit reverse) set-up could be used as the
      voltage sense trigger on an SE? In other words, wire the 555 such that
      power is switched to the motor when the 555 trigger senses that the
      capacitor is sufficiently charged. Does this make sense? Has anyone tried
      this before?

      Thanks!

      Johnny Flores
      University of Texas at San Antonio



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    • Drew Brown
      *sniff, *sniff do I smell a new 1-chip P-vore on the horizon? maybe a LM556 version ; Hunter of the 1-chip P-vores, DrewB ... From: Wilf Rigter To:
      Message 2 of 4 , Mar 15, 2003
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        *sniff, *sniff
        do I smell a new 1-chip P-vore on the horizon?
        maybe a LM556 version ;>
         
        Hunter of the 1-chip P-vores,
        DrewB
        ----- Original Message -----
        Sent: Saturday, March 15, 2003 1:19 AM
        Subject: Re: [beam] Re: 555 for a voltage sensor in a SE

        Hi Johnny ,

        any photodiodes will work. The trigger level is about 3 times the photo
        voltaic output of the PD. Add a series Si diode to raise the trigger level
        by 300mV (3x 100mV) .  Since the PD voltage rises with the log of the light
        level this means the PD voltage changes little over a large light range
        making the trigger level and the "pop" relatively constant.  The 555 with
        the PD with the lower output voltage will of course trigger first.  The cap
        should be sized to cause the motor to turn the bot no more than 45 degrees
        each pop. Any larger cap and the bot does "twirls".


        However your question "triggered" a new version that can use larger caps for
        longer pops by driving both motors at the same time but with a turning bias,
        which depends on the side triggered.
        As shown in the attached, the two diodes connect an active low output which
        drives a primary motor directly, also to the opposite motor. The diode drop
        reduces the voltage applied to the secondary motor so that it turns more
        slowly than the primary motor.

        regards

        wilf


        ----- Original Message -----
        From: "Johnny Flores" <jflores6@...>
        To: "Wilf Rigter" <Wilf.Rigter@...>; <beam@yahoogroups.com>
        Sent: Wednesday, March 12, 2003 1:45 PM
        Subject: [beam] Re: 555 for a voltage sensor in a SE


        Looks cool!  Are the diodes marked "PD" standard photodiodes or something
        else?  Any specific part number?  Also, I'm assuming that a larger cap
        (e.g., 6800uF) would cause a longer charge time but also a longer discharge
        time?

        Thanks again!

        Johnny
          ----- Original Message -----
          From: Wilf Rigter
          To: 'J Flores'
          Sent: Wednesday, March 12, 2003 12:04 PM
          Subject: RE: 555 for a voltage sensor in a SE


          oops, try this for that 555 article.

          http://groups.yahoo.com/group/beam/message/24457
            -----Original Message-----
            From: J Flores [mailto:jflores6@...]
            Sent: Wednesday, March 12, 2003 7:28 AM
            To: Wilf.Rigter@...
            Subject: 555 for a voltage sensor in a SE


            I read a "letter to the editors" in the current issue of Nuts and Volts
        that described the use of a 555 chip as part of a voltage sensing circuit in
        a battery charger.  It was set up with a voltage divider across the input
        and trigger pins (3 and 6?) such that when the power available from the
        battery dropped to a preset threshold, the 555 triggered a solid state relay
        to turn on the charger.

            I'm wondering if a similar (albeit reverse) set-up could be used as the
        voltage sense trigger on an SE?  In other words, wire the 555 such that
        power is switched to the motor when the 555 trigger senses that the
        capacitor is sufficiently charged.  Does this make sense?  Has anyone tried
        this before?

            Thanks!

            Johnny Flores
            University of Texas at San Antonio



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      • Drew Brown
        would this work? I noticed that CtrlVoltage and Discharge were not used and I got the PD s right (only because I coppied you original) DrewB ... From: Drew
        Message 3 of 4 , Mar 15, 2003
        • 0 Attachment
          would this work?
          I noticed that CtrlVoltage and Discharge were not used
          and I got the PD's right (only because I coppied you original)
          DrewB
          ----- Original Message -----
          Sent: Saturday, March 15, 2003 3:12 AM
          Subject: Re: [beam] Re: 555 for a voltage sensor in a SE

          *sniff, *sniff
          do I smell a new 1-chip P-vore on the horizon?
          maybe a LM556 version ;>
           
          Hunter of the 1-chip P-vores,
          DrewB
          ----- Original Message -----
          Sent: Saturday, March 15, 2003 1:19 AM
          Subject: Re: [beam] Re: 555 for a voltage sensor in a SE

          Hi Johnny ,

          any photodiodes will work. The trigger level is about 3 times the photo
          voltaic output of the PD. Add a series Si diode to raise the trigger level
          by 300mV (3x 100mV) .  Since the PD voltage rises with the log of the light
          level this means the PD voltage changes little over a large light range
          making the trigger level and the "pop" relatively constant.  The 555 with
          the PD with the lower output voltage will of course trigger first.  The cap
          should be sized to cause the motor to turn the bot no more than 45 degrees
          each pop. Any larger cap and the bot does "twirls".


          However your question "triggered" a new version that can use larger caps for
          longer pops by driving both motors at the same time but with a turning bias,
          which depends on the side triggered.
          As shown in the attached, the two diodes connect an active low output which
          drives a primary motor directly, also to the opposite motor. The diode drop
          reduces the voltage applied to the secondary motor so that it turns more
          slowly than the primary motor.

          regards

          wilf


          ----- Original Message -----
          From: "Johnny Flores" <jflores6@...>
          To: "Wilf Rigter" <Wilf.Rigter@...>; <beam@yahoogroups.com>
          Sent: Wednesday, March 12, 2003 1:45 PM
          Subject: [beam] Re: 555 for a voltage sensor in a SE


          Looks cool!  Are the diodes marked "PD" standard photodiodes or something
          else?  Any specific part number?  Also, I'm assuming that a larger cap
          (e.g., 6800uF) would cause a longer charge time but also a longer discharge
          time?

          Thanks again!

          Johnny
            ----- Original Message -----
            From: Wilf Rigter
            To: 'J Flores'
            Sent: Wednesday, March 12, 2003 12:04 PM
            Subject: RE: 555 for a voltage sensor in a SE


            oops, try this for that 555 article.

            http://groups.yahoo.com/group/beam/message/24457
              -----Original Message-----
              From: J Flores [mailto:jflores6@...]
              Sent: Wednesday, March 12, 2003 7:28 AM
              To: Wilf.Rigter@...
              Subject: 555 for a voltage sensor in a SE


              I read a "letter to the editors" in the current issue of Nuts and Volts
          that described the use of a 555 chip as part of a voltage sensing circuit in
          a battery charger.  It was set up with a voltage divider across the input
          and trigger pins (3 and 6?) such that when the power available from the
          battery dropped to a preset threshold, the 555 triggered a solid state relay
          to turn on the charger.

              I'm wondering if a similar (albeit reverse) set-up could be used as the
          voltage sense trigger on an SE?  In other words, wire the 555 such that
          power is switched to the motor when the 555 trigger senses that the
          capacitor is sufficiently charged.  Does this make sense?  Has anyone tried
          this before?

              Thanks!

              Johnny Flores
              University of Texas at San Antonio



          ---
          Outgoing mail is certified Virus Free.
          Checked by AVG anti-virus system (http://www.grisoft.com).
          Version: 6.0.459 / Virus Database: 258 - Release Date: 2/25/2003


          To unsubscribe from this group, send an email to:
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          To unsubscribe from this group, send an email to:
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