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Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

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  • Tom Hubin
    Hello wyverndudejfg, It is possible to create an appropriate disc pattern for higher speeds. But you may have the same problem as I expect you will have using
    Message 1 of 12 , Aug 2, 2003
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      Hello wyverndudejfg,

      It is possible to create an appropriate disc pattern for higher speeds.
      But you may have the same problem as I expect you will have using
      multiples of the original.

      The strobe light on time should be brief so that the pattern appears to
      be still when you see it. But the flourescent lighting takes some time
      to turn on then turn off. I do not know how much time that is. The disc
      will rotate a bit while the light is on and blur the pattern thereby
      making it harder to be sure of the RPM.

      First, if anybody knows the duration of a flourescent light then I can
      estimate the blurring. Second, maybe there is a faster firing type of
      flourescent light or other simple 110vac illumination.

      Third, it might be worth using a fast strobe light. Perhaps an
      automotive timing light triggered by 60 or 120 Hz.

      A neon light synced to 60 Hz or 120 Hz line power might be short enough
      in duration for an unblurred pattern at high speed.

      Tom Hubin
      thubin@...

      *******************

      wyverndudejfg wrote:
      >
      > <I have had success with Joe Martin's paper strobe disc. >
      > Ha! there you go!
      >
      > The one on the Sherline website
      > http://www.sherline.com/rpmgage.pdf
      > is only indicated good up to 2,400 RPM, but noticing there's eight
      > divisions for 1,800, four would sync at 3,600, and two divisions
      > would sync at 7,200; and ...it should sync up at multiples too.
      > 2,400 (three divisions) should sync again at 4,800, 7,200, and
      > 9,600RPM
      > 1,800 (four divisions) will sync again at 3,600, 5,400, 7,200, and
      > 9,000RPM; which will cover my speed range with the 10,000RPM pulley
      > set.
      >
      > Actually, ANY single point on the pulley will sync up at 7,200 RPM,
      > which gives at least one reference RPM.
      >
      > Very cool!
      >
      > Using the multiples won't be as straightforward as the Sherline
      > strobe -no option for the higher speed range- but with a mark on the
      > potentiometer for the ballpark, the strobe lines will sync up at the
      > exact RPM, so this really should work quite well!
      >
      > Thanks! I plan to try this tomorrow :)
      >
      > --- In SherlineCNC@yahoogroups.com, Tom Hubin <thubin@e...> wrote:
      > > Hello wyverndudejfg,
      > >
      > > > I will use black photographers' tape (just 'cause I happen to have
      > > > some) and put a stripe across the diameter of the spindle pulley,
      > > > shine the flashlight on it, and get the readings for a two-bladed
      > > > propeller.
      > >
      > > If the tach is erratic then try taping a pair of 90 degree arcs
      > instead
      > > of a straight line of tape. That will give a 50% duty cycle to the
      > > sensed signal. Depending on circuit design that could be more
      > reliable.
      > >
      > > I guess I would tape the entire pulley then cut two diameters with a
      > > blade then peel of the two quadrants that I don't want to be
      > blacked out
      > > with tape.
      > >
      > > BTW, I have had success with Joe Martin's paper strobe disc. I turn
      > out
      > > my ceiling light and my clamp-on tungsten work light but leave on a
      > > nearby workbench flouescent light. The flourescent light strobes
      > well
      > > enough to determine spindle RPM. In the daylight you need to close
      > the
      > > window blinds too.
      > >
      > > This is inconvenient but serves when I need to make a note of what
      > I did
      > > so I can do it again or tell somebody else how I did it. It would
      > also
      > > be adequate to just run at a variety of speeds and mark the speed
      > knob.
      > >
      > > Tom Hubin
      > > thubin@e...
      >
      >
      > To unsubscribe from this group, send an email to:
      > SherlineCNC-unsubscribe@yahoogroups.com
      >
      >
      >
      > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    • Dave Hylands
      I ve uploaded a version here: Or http://tinyurl.com/ivqz That goes upto 7200
      Message 2 of 12 , Aug 2, 2003
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        I've uploaded a version here:

        <http://groups.yahoo.com/group/sherline/files/RPM-Gauge/RPM-Gauge-60Hz-7
        200.pdf>

        Or http://tinyurl.com/ivqz

        That goes upto 7200 RPM (which is as fast as this type of gage can go).

        --
        Dave Hylands
        Vancouver, BC, Canada
        http://www.DaveHylands.com/


        > -----Original Message-----
        > From: wyverndudejfg [mailto:wyverndudejfg@...]
        > Sent: Saturday, August 02, 2003 11:10 PM
        > To: SherlineCNC@yahoogroups.com
        > Subject: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(
        >
        >
        > <I have had success with Joe Martin's paper strobe disc. >
        > Ha! there you go!
        >
        > The one on the Sherline website
        > http://www.sherline.com/rpmgage.pdf
        > is only indicated good up to 2,400 RPM, but noticing there's eight
        > divisions for 1,800, four would sync at 3,600, and two divisions
        > would sync at 7,200; and ...it should sync up at multiples
        > too. 2,400 (three divisions) should sync again at 4,800, 7,200, and
        > 9,600RPM
        > 1,800 (four divisions) will sync again at 3,600, 5,400, 7,200, and
        > 9,000RPM; which will cover my speed range with the 10,000RPM pulley
        > set.
        >
        > Actually, ANY single point on the pulley will sync up at 7,200 RPM,
        > which gives at least one reference RPM.
        >
        > Very cool!
        >
        > Using the multiples won't be as straightforward as the Sherline
        > strobe -no option for the higher speed range- but with a mark on the
        > potentiometer for the ballpark, the strobe lines will sync up at the
        > exact RPM, so this really should work quite well!
        >
        > Thanks! I plan to try this tomorrow :)
        >
        >
        > --- In SherlineCNC@yahoogroups.com, Tom Hubin <thubin@e...> wrote:
        > > Hello wyverndudejfg,
        > >
        > > > I will use black photographers' tape (just 'cause I happen to have
        > > > some) and put a stripe across the diameter of the spindle pulley,
        > > > shine the flashlight on it, and get the readings for a two-bladed
        > > > propeller.
        > >
        > > If the tach is erratic then try taping a pair of 90 degree arcs
        > instead
        > > of a straight line of tape. That will give a 50% duty cycle to the
        > > sensed signal. Depending on circuit design that could be more
        > reliable.
        > >
        > > I guess I would tape the entire pulley then cut two
        > diameters with a
        > > blade then peel of the two quadrants that I don't want to be
        > blacked out
        > > with tape.
        > >
        > > BTW, I have had success with Joe Martin's paper strobe disc. I turn
        > out
        > > my ceiling light and my clamp-on tungsten work light but leave on a
        > > nearby workbench flouescent light. The flourescent light strobes
        > well
        > > enough to determine spindle RPM. In the daylight you need to close
        > the
        > > window blinds too.
        > >
        > > This is inconvenient but serves when I need to make a note of what
        > I did
        > > so I can do it again or tell somebody else how I did it. It would
        > also
        > > be adequate to just run at a variety of speeds and mark the speed
        > knob.
        > >
        > > Tom Hubin
        > > thubin@e...
        >
        >
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      • Ron Thompson
        I stand corrected. Thanks for your report to the group. Ron Thompson On the Beautiful Mississippi Gulf Coast USA http://www.plansandprojects.com Where did
        Message 3 of 12 , Aug 3, 2003
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          I stand corrected. Thanks for your report to the group.

          Ron Thompson
          On the Beautiful Mississippi Gulf Coast
          USA
           
           
          Where did everyone go? Oh, yeah. <http://groups.yahoo.com/group/castinghobby/>
          Y'all come, ya hear?
          *******
          ----- Original Message -----
          Sent: Sunday, August 03, 2003 12:14 AM
          Subject: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

          3rd digit is 10ths, so it can't read 999.  Not on the one I bought
          anyway.  Highest -as noted- is 99.9 (999RPM with a 167cm wheel
          circumference setting); which is way, way faster than anybody has any
          business riding any bicycle!
          Even if it was capable of being calibrated to a 16.7cm wheel (which
          it's not, it can only go down to 94cm) that would only adjust the
          display, and would do nothing to cure the problem of apparent switch
          bounce.  It's just -apparently- not intended to be able to read a
          signal that fast.  In the intended application, there is no reason
          why it should.
          It did give good results up to about 900RPM -which would be 90Km/hr
          or about 55MPH- plenty fast enough for a bicycle speedometer... or a
          R/C helicopter head rotor tach.

          I noticed that the one used on the R/C helicopter, oddly enough, has
          a FIVE digit (including 100ths) display!  This means his bicycle
          speedometer is capable of clocking speeds up to 999.99Km/hr!  For a
          bicycle?
          Apparently the five-digit part of the display is used for other
          things as well, the manufacturer had five digits, so they used them. 
          Note that his main display likewise has only three digits.






          --- In SherlineCNC@yahoogroups.com, "Ron Thompson" <thom1486@b...>
          wrote:
          > I stated that you use 167cm on the KPH range. This makes it read
          out in RPM X 10. So a 3 digit display reads out to 999 which is read
          as 9990 RPM.
          >
          > Ron Thompson
          > On the Beautiful Mississippi Gulf Coast
          > USA
          >
          > http://www.plansandprojects.com
          >
          > Where did everyone go? Oh, yeah.
          <http://groups.yahoo.com/group/castinghobby/>
          > Y'all come, ya hear?
          > *******
          >   ----- Original Message -----
          >   From: wyverndudejfg
          >   To: SherlineCNC@yahoogroups.com
          >   Sent: Saturday, August 02, 2003 6:19 PM
          >   Subject: [SherlineCNC] Bike Speedo Spindle tach: No go :(
          >
          >
          >   Today I bought a CatEye "Mity 3" Cyclocomputer -digital
          electronic
          >   bicycle speedometer, with magnetic pickup.
          >
          >   Unfortunately, it doesn't work.
          >
          >   Note: the web page article about the R/C helicopter was incorrect
          in
          >   specifying 1667mm as the wheel *diameter*, as indeed, it is the
          wheel
          >   *circumference* that you set to calibrate the speedometer.
          >   This particular model I bought is limited to a wheel
          circumference
          >   range of 94 to 220cm -but that does cover the 1667mm noted. 
          (must be
          >   entered as 167cm, but pretty close).
          >
          >   Set to 167cm, readings are erratic.  At full speed (I have the
          >   10,000RPM pulley set) it gives up and reads zero.  It uses a
          magnetic
          >   reed switch (not gonna be Hall effect at consumer-grade price
          >   levels!) and I believe the problem is caused by switch bounce.
          >
          >
          >
          >   Just the same, I find I am guilty of acting before thinking it
          all
          >   the way through...  (sure glad I kept my receipt!)
          >
          >   10,000RPM on a 167cm wheel would be 1,000Km/Hr.  Even 3,000RPM
          would
          >   be 300Km/Hr.  No wonder the speedo gets confused.  Even if it
          didn't,
          >   it only has a three digit display, so max RPM it could read would
          be
          >   999RPM.  (display would be 99.9Km)
          >
          >   I suppose this should have been obvious.  My math was good, I
          just
          >   didn't do quite enough of it.
          >
          >
          >
          >   I'm back to the R/C airplane optical tach idea. 
          >
          >   Al brought up a really good point about needing a constant light
          >   source, which any AC lighting is NOT prone to be.
          >
          >   But since the tach is designed to be handheld anyway -and do you
          >   really need a continuous speed readout?- I'm figuring on using a
          >   flashlight.
          >
          >   Although the Tower Hobbies optical tach tech notes indicate that
          it
          >   has to have the sun behind the propeller, I found my tach to be
          >   extremely forgiving, requiring no special lighting conditions of
          any
          >   kind.  I was usually working inside a garage, and always got
          reliable
          >   readings off of black and gray plastic, as well as blonde wood
          >   propellers.  Even with contrasting writing on them (the
          manufacturers
          >   name/logo).  I'm confident that it will work happily with a
          >   flashlight.
          >
          >   I will use black photographers' tape (just 'cause I happen to
          have
          >   some) and put a stripe across the diameter of the spindle pulley,
          >   shine the flashlight on it, and get the readings for a two-bladed
          >   propeller.
          >
          >   From that I will mark a scale on my speed control potentiometer
          and
          >   call it good.
          >
          >   A mounted version could be effected readily enough by using a DC
          >   power supply for the light -you'd want DC power for the normally
          >   battery-operated tach anyway... but I'm not planning to do all
          that.
          >
          >
          >   I'll let y'all know how it works out!  :)
          >
          >
          >
          >
          >
          >   To unsubscribe from this group, send an email to:
          >   SherlineCNC-unsubscribe@yahoogroups.com
          >
          >   
          >
          >   Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/


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        • Ron Thompson
          Hmmm... Ive notice the LED lights on big trucks have a much faster on and off time that a regular incandescent bulb. I wonder if one of the jumbo bright white
          Message 4 of 12 , Aug 3, 2003
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            Hmmm... Ive notice the LED lights on big trucks have a much faster on and off time that a regular incandescent bulb. I wonder if one of the jumbo bright white LEDs could be used with a diode and a resistor and plugged into the wall for a 60 Hz strobe?

            Ron Thompson
            On the Beautiful Mississippi Gulf Coast
            USA
             
             
            Where did everyone go? Oh, yeah. <http://groups.yahoo.com/group/castinghobby/>
            Y'all come, ya hear?
            *******
            ----- Original Message -----
            From: Tom Hubin
            Sent: Sunday, August 03, 2003 1:27 AM
            Subject: Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

            Hello wyverndudejfg,

            It is possible to create an appropriate disc pattern for higher speeds.
            But you may have the same problem as I expect you will have using
            multiples of the original.

            The strobe light on time should be brief so that the pattern appears to
            be still when you see it. But the flourescent lighting takes some time
            to turn on then turn off. I do not know how much time that is. The disc
            will rotate a bit while the light is on and blur the pattern thereby
            making it harder to be sure of the RPM.

            First, if anybody knows the duration of a flourescent light then I can
            estimate the blurring. Second, maybe there is a faster firing type of
            flourescent light or other simple 110vac illumination.

            Third, it might be worth using a fast strobe light. Perhaps an
            automotive timing light triggered by 60 or 120 Hz.

            A neon light synced to 60 Hz or 120 Hz line power might be short enough
            in duration for an unblurred pattern at high speed.

            Tom Hubin
            thubin@...

            *******************

            wyverndudejfg wrote:
            >
            > <I have had success with Joe Martin's paper strobe disc. >
            > Ha!  there you go!
            >
            > The one on the Sherline website
            > http://www.sherline.com/rpmgage.pdf
            > is only indicated good up to 2,400 RPM, but noticing there's eight
            > divisions for 1,800, four would sync at 3,600, and two divisions
            > would sync at 7,200; and ...it should sync up at multiples too.
            > 2,400 (three divisions) should sync again at 4,800, 7,200, and
            > 9,600RPM
            > 1,800 (four divisions) will sync again at 3,600, 5,400, 7,200, and
            > 9,000RPM; which will cover my speed range with the 10,000RPM pulley
            > set.
            >
            > Actually, ANY single point on the pulley will sync up at 7,200 RPM,
            > which gives at least one reference RPM.
            >
            > Very cool!
            >
            > Using the multiples won't be as straightforward as the Sherline
            > strobe -no option for the higher speed range- but with a mark on the
            > potentiometer for the ballpark, the strobe lines will sync up at the
            > exact RPM, so this really should work quite well!
            >
            > Thanks!  I plan to try this tomorrow  :)
            >
            > --- In SherlineCNC@yahoogroups.com, Tom Hubin <thubin@e...> wrote:
            > > Hello wyverndudejfg,
            > >
            > > > I will use black photographers' tape (just 'cause I happen to have
            > > > some) and put a stripe across the diameter of the spindle pulley,
            > > > shine the flashlight on it, and get the readings for a two-bladed
            > > > propeller.
            > >
            > > If the tach is erratic then try taping a pair of 90 degree arcs
            > instead
            > > of a straight line of tape. That will give a 50% duty cycle to the
            > > sensed signal. Depending on circuit design that could be more
            > reliable.
            > >
            > > I guess I would tape the entire pulley then cut two diameters with a
            > > blade then peel of the two quadrants that I don't want to be
            > blacked out
            > > with tape.
            > >
            > > BTW, I have had success with Joe Martin's paper strobe disc. I turn
            > out
            > > my ceiling light and my clamp-on tungsten work light but leave on a
            > > nearby workbench flouescent light. The flourescent light strobes
            > well
            > > enough to determine spindle RPM. In the daylight you need to close
            > the
            > > window blinds too.
            > >
            > > This is inconvenient but serves when I need to make a note of what
            > I did
            > > so I can do it again or tell somebody else how I did it. It would
            > also
            > > be adequate to just run at a variety of speeds and mark the speed
            > knob.
            > >
            > > Tom Hubin
            > > thubin@e...
            >
            >
            > To unsubscribe from this group, send an email to:
            > SherlineCNC-unsubscribe@yahoogroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


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          • Tom Hubin
            ... I mispoke when I said 60 Hz earlier. The disc is setup for 120 Hz. A flourescent lamp fires on the positive cycle and on the negative cycle. Joe Martin
            Message 5 of 12 , Aug 3, 2003
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              Ron Thompson wrote:
              >
              > Hmmm... Ive notice the LED lights on big trucks have a much faster on
              > and off time that a regular incandescent bulb. I wonder if one of the
              > jumbo bright white LEDs could be used with a diode and a resistor and
              > plugged into the wall for a 60 Hz strobe?
              >
              > Ron Thompson
              > On the Beautiful Mississippi Gulf Coast
              > USA

              I mispoke when I said 60 Hz earlier. The disc is setup for 120 Hz. A
              flourescent lamp fires on the positive cycle and on the negative cycle.
              Joe Martin makes reference to 60 Hz in is explanation of the disc. He is
              incorrect. It is designed to work with a 120 Hz light source.

              An led would work at 10 ma with a 1.5 v drop for red LED or a 3.5 v drop
              for a white or blue LED. The LED is fast but the AC power line is not.
              Stiil, it might work well enough.

              If you try to run from the 120vac power line then the piddling voltage
              drop across the diode can be ignored. But the diode is not made to
              withstand the 170vdc reverse bias of the ac line.

              You should be able to use a full wave rectifier to produce 120 Hz and to
              eliminate the reverse bias. Then a resistor of 120v * sqrt(2) / 10 ma =
              17 kohms. The peak power rating would be 120v * sqrt(2) * 10 ma = 1.7
              watts.

              The exact values are not important. Resistor value in the 10kohm to
              30kohm range should work with any color LED. Power rating of 2 watts or
              greater should be adequate.

              A watt or two heating a resistor can be hot to the touch so do not be
              surprised if the resistor is very warm if you leave it on for a while.

              Neon bulbs do not require a full wave rectifier since they are not
              diodes. You might try one of those ac circuit testers that uses a neon
              bulb with built in resistor to show that the ac outlet is hot. Not very
              bright but might be adequate in a darkened room for an occassional
              check.

              Remember the old turntables with stobe pattern on the turntable
              perimeter? That used a neon bulb to illuminate the strobe pattern so you
              could tweak the turntable speed for exactly 33.333333333333333 RPM.;)

              Tom Hubin
              thubin@...
            • Carol & Jerry Jankura
              Hi, Ron: The keys to making all of this work are: 1. The light level should actually go to zero at some time. The phosphors in fluorescent lamps are designed
              Message 6 of 12 , Aug 3, 2003
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                Hi, Ron:
                 
                The keys to making all of this work are:
                 
                1. The light level should actually go to zero at some time. The phosphors in fluorescent lamps are designed to have a decay time that keeps them emitting some light as the current level goes to zero and the arc turns off momentarily. If I remember correctly, I measured about a 25% ripple on a 40 watt cool white fluorescent lamp running a standard magnetic ballast.
                 
                2. The source should provide a short, high intensity spike of light.
                 
                I would expect that an LED driven by a pulsed DC source would make an excellent strobe. I'd use the 60 Hertz  AC output of a transformer to trigger a monostable multivibrator that actually drives the led through a power tansistor. Or, you can simply use a power transformer and a resistor to drive the LED. Put a standard diode across the LED in reverse polarity to keep the reverse half of the voltage cycle from exceeding the PIV (peak inverse voltage) of the LED.
                 
                -- Jerry
                 
                 -----Original Message-----
                From: Ron Thompson [mailto:thom1486@...]
                Sent: Sunday, August 03, 2003 8:59 AM
                To: SherlineCNC@yahoogroups.com
                Subject: Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

                Hmmm... Ive notice the LED lights on big trucks have a much faster on and off time that a regular incandescent bulb. I wonder if one of the jumbo bright white LEDs could be used with a diode and a resistor and plugged into the wall for a 60 Hz strobe?

                Ron Thompson
                On the Beautiful Mississippi Gulf Coast
                USA
                 
                 
                Where did everyone go? Oh, yeah. <http://groups.yahoo.com/group/castinghobby/>
                Y'all come, ya hear?
                *******
                ----- Original Message -----
                From: Tom Hubin
                Sent: Sunday, August 03, 2003 1:27 AM
                Subject: Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

                Hello wyverndudejfg,

                It is possible to create an appropriate disc pattern for higher speeds.
                But you may have the same problem as I expect you will have using
                multiples of the original.

                The strobe light on time should be brief so that the pattern appears to
                be still when you see it. But the flourescent lighting takes some time
                to turn on then turn off. I do not know how much time that is. The disc
                will rotate a bit while the light is on and blur the pattern thereby
                making it harder to be sure of the RPM.

                First, if anybody knows the duration of a flourescent light then I can
                estimate the blurring. Second, maybe there is a faster firing type of
                flourescent light or other simple 110vac illumination.

                Third, it might be worth using a fast strobe light. Perhaps an
                automotive timing light triggered by 60 or 120 Hz.

                A neon light synced to 60 Hz or 120 Hz line power might be short enough
                in duration for an unblurred pattern at high speed.

                Tom Hubin
                thubin@...

                *******************

                wyverndudejfg wrote:
                >
                > <I have had success with Joe Martin's paper strobe disc. >
                > Ha!  there you go!
                >
                > The one on the Sherline website
                > http://www.sherline.com/rpmgage.pdf
                > is only indicated good up to 2,400 RPM, but noticing there's eight
                > divisions for 1,800, four would sync at 3,600, and two divisions
                > would sync at 7,200; and ...it should sync up at multiples too.
                > 2,400 (three divisions) should sync again at 4,800, 7,200, and
                > 9,600RPM
                > 1,800 (four divisions) will sync again at 3,600, 5,400, 7,200, and
                > 9,000RPM; which will cover my speed range with the 10,000RPM pulley
                > set.
                >
                > Actually, ANY single point on the pulley will sync up at 7,200 RPM,
                > which gives at least one reference RPM.
                >
                > Very cool!
                >
                > Using the multiples won't be as straightforward as the Sherline
                > strobe -no option for the higher speed range- but with a mark on the
                > potentiometer for the ballpark, the strobe lines will sync up at the
                > exact RPM, so this really should work quite well!
                >
                > Thanks!  I plan to try this tomorrow  :)
                >
                > --- In SherlineCNC@yahoogroups.com, Tom Hubin <thubin@e...> wrote:
                > > Hello wyverndudejfg,
                > >
                > > > I will use black photographers' tape (just 'cause I happen to have
                > > > some) and put a stripe across the diameter of the spindle pulley,
                > > > shine the flashlight on it, and get the readings for a two-bladed
                > > > propeller.
                > >
                > > If the tach is erratic then try taping a pair of 90 degree arcs
                > instead
                > > of a straight line of tape. That will give a 50% duty cycle to the
                > > sensed signal. Depending on circuit design that could be more
                > reliable.
                > >
                > > I guess I would tape the entire pulley then cut two diameters with a
                > > blade then peel of the two quadrants that I don't want to be
                > blacked out
                > > with tape.
                > >
                > > BTW, I have had success with Joe Martin's paper strobe disc. I turn
                > out
                > > my ceiling light and my clamp-on tungsten work light but leave on a
                > > nearby workbench flouescent light. The flourescent light strobes
                > well
                > > enough to determine spindle RPM. In the daylight you need to close
                > the
                > > window blinds too.
                > >
                > > This is inconvenient but serves when I need to make a note of what
                > I did
                > > so I can do it again or tell somebody else how I did it. It would
                > also
                > > be adequate to just run at a variety of speeds and mark the speed
                > knob.
                > >
                > > Tom Hubin
                > > thubin@e...
                >
                >
                > To unsubscribe from this group, send an email to:
                > SherlineCNC-unsubscribe@yahoogroups.com
                >
                >
                >
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              • Ron Thompson
                Sounds right to me. Depends on what you have on hand. I was trying to keep it simple. Ron Thompson On the Beautiful Mississippi Gulf Coast USA
                Message 7 of 12 , Aug 3, 2003
                • 0 Attachment
                  Sounds right to me. Depends on what you have on hand. I was trying to keep it simple.

                  Ron Thompson
                  On the Beautiful Mississippi Gulf Coast
                  USA
                   
                   
                  Where did everyone go? Oh, yeah. <http://groups.yahoo.com/group/castinghobby/>
                  Y'all come, ya hear?
                  *******
                  ----- Original Message -----
                  Sent: Sunday, August 03, 2003 12:59 PM
                  Subject: RE: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

                  Hi, Ron:
                   
                  The keys to making all of this work are:
                   
                  1. The light level should actually go to zero at some time. The phosphors in fluorescent lamps are designed to have a decay time that keeps them emitting some light as the current level goes to zero and the arc turns off momentarily. If I remember correctly, I measured about a 25% ripple on a 40 watt cool white fluorescent lamp running a standard magnetic ballast.
                   
                  2. The source should provide a short, high intensity spike of light.
                   
                  I would expect that an LED driven by a pulsed DC source would make an excellent strobe. I'd use the 60 Hertz  AC output of a transformer to trigger a monostable multivibrator that actually drives the led through a power tansistor. Or, you can simply use a power transformer and a resistor to drive the LED. Put a standard diode across the LED in reverse polarity to keep the reverse half of the voltage cycle from exceeding the PIV (peak inverse voltage) of the LED.
                   
                  -- Jerry
                   
                   -----Original Message-----
                  From: Ron Thompson [mailto:thom1486@...]
                  Sent: Sunday, August 03, 2003 8:59 AM
                  To: SherlineCNC@yahoogroups.com
                  Subject: Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

                  Hmmm... Ive notice the LED lights on big trucks have a much faster on and off time that a regular incandescent bulb. I wonder if one of the jumbo bright white LEDs could be used with a diode and a resistor and plugged into the wall for a 60 Hz strobe?

                  Ron Thompson
                  On the Beautiful Mississippi Gulf Coast
                  USA
                   
                   
                  Where did everyone go? Oh, yeah. <http://groups.yahoo.com/group/castinghobby/>
                  Y'all come, ya hear?
                  *******
                  ----- Original Message -----
                  From: Tom Hubin
                  Sent: Sunday, August 03, 2003 1:27 AM
                  Subject: Re: [SherlineCNC] Re: Bike Speedo Spindle tach: No go :(

                  Hello wyverndudejfg,

                  It is possible to create an appropriate disc pattern for higher speeds.
                  But you may have the same problem as I expect you will have using
                  multiples of the original.

                  The strobe light on time should be brief so that the pattern appears to
                  be still when you see it. But the flourescent lighting takes some time
                  to turn on then turn off. I do not know how much time that is. The disc
                  will rotate a bit while the light is on and blur the pattern thereby
                  making it harder to be sure of the RPM.

                  First, if anybody knows the duration of a flourescent light then I can
                  estimate the blurring. Second, maybe there is a faster firing type of
                  flourescent light or other simple 110vac illumination.

                  Third, it might be worth using a fast strobe light. Perhaps an
                  automotive timing light triggered by 60 or 120 Hz.

                  A neon light synced to 60 Hz or 120 Hz line power might be short enough
                  in duration for an unblurred pattern at high speed.

                  Tom Hubin
                  thubin@...

                  *******************

                  wyverndudejfg wrote:
                  >
                  > <I have had success with Joe Martin's paper strobe disc. >
                  > Ha!  there you go!
                  >
                  > The one on the Sherline website
                  > http://www.sherline.com/rpmgage.pdf
                  > is only indicated good up to 2,400 RPM, but noticing there's eight
                  > divisions for 1,800, four would sync at 3,600, and two divisions
                  > would sync at 7,200; and ...it should sync up at multiples too.
                  > 2,400 (three divisions) should sync again at 4,800, 7,200, and
                  > 9,600RPM
                  > 1,800 (four divisions) will sync again at 3,600, 5,400, 7,200, and
                  > 9,000RPM; which will cover my speed range with the 10,000RPM pulley
                  > set.
                  >
                  > Actually, ANY single point on the pulley will sync up at 7,200 RPM,
                  > which gives at least one reference RPM.
                  >
                  > Very cool!
                  >
                  > Using the multiples won't be as straightforward as the Sherline
                  > strobe -no option for the higher speed range- but with a mark on the
                  > potentiometer for the ballpark, the strobe lines will sync up at the
                  > exact RPM, so this really should work quite well!
                  >
                  > Thanks!  I plan to try this tomorrow  :)
                  >
                  > --- In SherlineCNC@yahoogroups.com, Tom Hubin <thubin@e...> wrote:
                  > > Hello wyverndudejfg,
                  > >
                  > > > I will use black photographers' tape (just 'cause I happen to have
                  > > > some) and put a stripe across the diameter of the spindle pulley,
                  > > > shine the flashlight on it, and get the readings for a two-bladed
                  > > > propeller.
                  > >
                  > > If the tach is erratic then try taping a pair of 90 degree arcs
                  > instead
                  > > of a straight line of tape. That will give a 50% duty cycle to the
                  > > sensed signal. Depending on circuit design that could be more
                  > reliable.
                  > >
                  > > I guess I would tape the entire pulley then cut two diameters with a
                  > > blade then peel of the two quadrants that I don't want to be
                  > blacked out
                  > > with tape.
                  > >
                  > > BTW, I have had success with Joe Martin's paper strobe disc. I turn
                  > out
                  > > my ceiling light and my clamp-on tungsten work light but leave on a
                  > > nearby workbench flouescent light. The flourescent light strobes
                  > well
                  > > enough to determine spindle RPM. In the daylight you need to close
                  > the
                  > > window blinds too.
                  > >
                  > > This is inconvenient but serves when I need to make a note of what
                  > I did
                  > > so I can do it again or tell somebody else how I did it. It would
                  > also
                  > > be adequate to just run at a variety of speeds and mark the speed
                  > knob.
                  > >
                  > > Tom Hubin
                  > > thubin@e...
                  >
                  >
                  > To unsubscribe from this group, send an email to:
                  > SherlineCNC-unsubscribe@yahoogroups.com
                  >
                  >
                  >
                  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


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