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Encoder as tach?

Discussion in 'Electronic Basics' started by BR, Oct 15, 2003.

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  1. BR

    BR Guest

    Hello. I'd like to limit the speed of this motor by using the encoder output
    and converting frequency to voltage.

    I was told it was 2500ppr 5V TTL quadrature output. Tried 5V to "ENC. PWR"
    and ground to "COMMON" and "SHLD". None of the other connections showed a
    usable TTL output. Example; "ORANGE" showed a square wave well below 1V. How
    do you hook up these things. I have no docs on this unit nor do I know
    anything about encoders. The brushed DC motor runs fine however.

    Your help appreciated.


  2. John Fields

    John Fields Guest

    Try pulling up the orange lead to +5V through a 10k resistor. There
    should also be another wire which you'll need to pull up, and if you
    look at the outputs when they're pulled up, with the motor running,
    you'll see two square waves 90° apart in phase. You could probably use
    1k pullups if you had to.
  3. happyhobit

    happyhobit Guest

    You are measuring between the ‘A’ or ‘B’ outputs and +5 volts correct.

    TTL output is 0 volts or high impedance. Measuring to ground don’t work.


  4. I expect the outputs are "open collector" - you will need to supply a
    pull-up resistor (5K1 or so) to +5 to see a useful output.
  5. BR

    BR Guest

    Thanks. 10K works fine.

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