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Thread: Dual LightSpeed and RPM Board

  1. #1

    Dual LightSpeed and RPM Board

    Hey AFS. I have been using your RPM board connected to the RPM signal outputs of my dual LightSpeed Plasma III setup to display RPM on AFS screens. The other day I decided to hookup the LIghtSpeed LCD and compare the RPM readings coming from the LightSpeed system to what was being displayed on the AFS screen. To my surprise the LightSpeed LCD was reading 100 RPM lower than the AFS. What gives?

    BTW- I have dual 4500 screens with the synthetic vision CPU and latest software.

    Thanks,

    Jason

  2. #2
    Jason, the Lightspeed LCD uses an averaged number. I think if you got a separate RPM indicating instrument (one of those portable ones you point at the prop), you'd find the AF-4500 is extremely accurate. This is also the case with Pmag/Emag's serial connection to a computer which outputs to their software program. The RPM is very averaged and never to be used in-flight as an indication of actual RPM.
    ---
    Trevor Conroy
    Technical Support
    Advanced Flight Systems
    Support@Advanced-Flight-Systems.com

  3. #3
    Klaus from LightSpeed provided this response:


    The pulse output is very correct so the numbers on your AFS should be the right ones.
    Note that the LCD reads very low voltages it is therefore susceptible to EMI and grounding errors of the CDI.
    It has nothing to do with averaging, the LCD rpm can be accurate to 1 rpm. You can try to swap the output connectors and see if the rpm from the other Plasma III is more accurate.
    It is adjustable internally.

  4. #4
    Double check it with a hand held RPM tach from a hobby store. We have been down this path before and so far we have always been proved to be correct.

    You could also put a voltmeter that has frequency measuring on the line from the lightspeed to verify that it is correct.
    Rob Hickman
    Advanced Flight Systems Inc.

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