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rpm of a dc motor — Parallax Forums

rpm of a dc motor

mazur50mazur50 Posts: 2
edited 2007-04-20 16:43 in BASIC Stamp
What product would i use to Datalog the voltage and amperage and rpm of a dc motor. and for the rpm i want to count the com segments to get rpm.

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2007-04-19 16:39
    How big is the motor and what full load amps do you expect? Is it going to be reversing?

    Voltage and current are both relatively easy using an a/d converter.

    Unless the comm segments are real easy to get at, its probably going to be easier to put some kind of optical interrupter on the shaft and use the COUNT or PULSIN functions to watch the disk go by.

    Cheers,

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    Tom Sisk

    http://www.siskconsult.com
    ·
  • mazur50mazur50 Posts: 2
    edited 2007-04-20 16:10
    it is a small slotcar motor and max amps would me in the area of 8 amps.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2007-04-20 16:43
    mazur50,

    8 Amps! ...that's one heck of a slot car. Do you have access to a Scope where you could scope the power supply, or voltage across the motor? Most likely, the motor will have 3 or 5 armature coils which will
    also reflect the number of contacts. By measuring the frequency injected onto the DC supply by the brushes/contacts, you can calculate the rpm, by dividing that frequency by the number of armature coils.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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