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Re: [mlathemods] Re: Digest Number 474

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  • Roy E. Burrage
    Try this one Brewster: http://www.allegromicro.com/ Be careful, though, to order plenty of spares so you don t have to hunt replacements in the future. I
    Message 1 of 3 , Aug 6, 2006
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      Try this one Brewster:

      http://www.allegromicro.com/

      Be careful, though, to order plenty of spares so you don't have to hunt
      replacements in the future. I designed a small board a few years ago to
      use one of their stepper motor drivers. This was a drop-in replacement
      for the old Philips SAA1027 chips used in several items of equipment we
      service. About 2 years after designing the board, and having many
      adapters in the field, they obsoleted the chips with no replacement and
      no warning so users could make a last time buy. Many manufacturers do
      this so it isn't uncommon. Just be aware if you have to build a special
      mount of some sort.

      Since you're going to use this in your scooter, you might want to be
      sure to check the temperatures you'll be exposing it to. If it's right
      there at the engine you might want to think about using a magnetic
      pickup of some sort. Check out the PK series at Minarik Electric:

      http://www.minarik.com/PDFs/250-0041.pdf

      We buy PK1s and PK3s from ElectroRep/Prep-Power at (704) 527-2530. I
      believe Red Lion Controls also has a model in their line. You can also
      take a look at the magnetic pickups that were used in some of the older
      automotive electronic ignition systems.

      The advantage of using a mag pickup in an add-on system is that you can
      use an existing bolt head, hole in a shaft or wheel, shaft key or keyway
      slot, a gear tooth, or any other anomaly on a shaft or wheel. You also
      don't have to worry about temperature. The potential problem is that at
      high speeds the output can be as high as 90 or 100 volts, but this can
      be taken care of with a resistor and a zener diode. They may be a bit
      more expensive by a couple of bucks, but they're more rugged and you
      don't have to add a magnet to be able to get the sensor out of the way
      of the mechanics. They can also be physically larger.


      REB



      imbrewster2 wrote:

      >Jeff
      >Are you sure about the web site? www.allegro.com is promoting HP
      >computer stuff.
      >
      >Brewster
      >
      >--- In mlathemods@yahoogroups.com, "Jeff Demand" <jdemand@...> wrote:
      >
      >
      >>Brewster,
      >>
      >> Try www.allegro.com Quite a range of choices, good data
      >>
      >>
      >sheets, and up
      >
      >
      >>to 6 free samples (at a time ;-) Really easy, I used one for a
      >>
      >>
      >spindle
      >
      >
      >>encoder... 1/8" radio shack magnet, a ls7414 schmitt trigger
      >>
      >>
      >(probably not
      >
      >
      >>really needed) and TurboCnc.
      >>
      >>Jeff
      >>


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