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Dynamometer plans/schematics

Discussion in 'Electronic Design' started by Ba`al, Jan 11, 2006.

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  1. Ba`al

    Ba`al Guest

    Hello all. It's been a long time for me being away from electronics so
    I need some assistance.

    I'm trying to build a low power, rear wheel inertial dynamometer.
    Power ratings are up to maybe 100HP. While I have some plans for the
    frame of the unit and the roller, I do not have any plans for sensors
    or cables. I also haven't found any software either.

    So the questions are.

    What will I need to use for a sensor on the drum?

    Using a simple laptop (p2 700) what software can I use to interface
    with the sensor?

    Having had no previous experience with rs232, how will I need to wire
    the cable going from the sensor to the laptop?

    Yes I know it's a tall order. Any help is appreciated. If you have any
    plans or sites that you know about that would be awesome too.

    Ba`al |
  2. Back on 7/16/04 I started a thread on homebrew dynamometer ideas that may be
    of some help. I have not yet completed the project, but the basic idea I had
    was to couple the driveshaft (or rollers) to a generator and apply a
    variable PWM load to a resistor bank (such as an electric furnace) to
    provide a measure of horsepower (or kW). You need to take into account the
    efficiency of the generator (or measure its temperature rise) for better
    accuracy. The torque is a little more difficult, but could be accomplished
    with digital scales. If this is an automotive application, you could put
    scales under the front wheels, and measure the difference in weight and the
    distance from the back wheels. You can also measure the RPM fairly
    accurately so you have a third value to make sure the data seems reasonable.

    There should be various sensors available that convert weight, RPM, and
    wattage to A/D friendly signals like 0-5 VDC. There are numerous data
    collection packages available for serial, parallel, USB, etc. Most software
    is essentially like a digital chart recorder for each value. You may need to
    process the data to get a readout of torque, power, and velocity based on
    the sensors you have, in units you want.

    Good luck!

    Paul E. Schoen, President
    P S Technology, Inc.
    Cockeysville, MD 21030-2824
  3. Rick

    Rick Guest

    60 tooth wheel and mag pickup would work. Frequency will be the same as the RPM.
    Can use a F to V if you need an analog signal.

    Probably have to write your own. Suggest you do some more reading on inertial dynamometer
    Try here:

    For a frequency input you might be able to use a sound card or a zero crossing detector
    (radio guys use them for RTTY decoding)
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