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• BACKGROUND
  • This web site assumes that you are familiar with the history and technology to replace the kilogram with an electronic balance, and with the NIST D.I.Y. LEGO® Watt Balance tabletop model of the Watt (Kibble) balance. If you need some background, try the links below.
  • Note that LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this site.
  • Note also that NIST, the US National Institute of Standards and Technology, does not sponsor, authorize or endorse this site.
  • Here are some of the links that I found useful in understanding the D.I.Y. LEGO® Watt Balance:

  ------------------best starting links-----------------

  Vimeo video: This is not a toy: a LEGO tabletop watt balance Introduction by NIST
  

  Youtube Video: How to Build Your NIST D.I.Y. Watt Balance Introduction by NIST
  

  Youtube video: The Watt Balance and Defining the Kilogram a discussion including Dr Bryan Kibble, the inventor of the balance.
  

  Pdf of journal article: A Lego Watt Balance - technical details of NIST design with parts list and software link
  

  Science Daily: Measuring Planck's constant, NIST's watt balance brings world closer to new kilogram - 2016 brief summary article
  

  --------------added information links-------------

  Youtube video MSL LEGO Kibble Balance by the Measurements Standards Laboratory of NZ.
  

  Youtube video from Practical Engineering: Redefining the Kilogram with the DIY Watt Balance wooden design for WB
  

  Youtube video from Practical Engineering: Building the Desktop Watt Balance and FAQ wooden design for WB
  

  Facebook page for LEGO Watt Balance
  

  Pdf of University of Oslo physics department student project LEGO Watt Balance attempt to build the NIST LWB
  

  Google Search for "lego watt balance" web links
  

  Youtube video: LEGO Watt Balance Build shows construction of LEGO structure.
  

  Google Group DIY Lego Watt Kibble Balance email discussion list for discussions with other LWB builders.

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• HACKS TO IMPROVE THE LEGO WATT BALANCE PERFORMANCE

  I am using the word HACK in the sense of "a clever modification or improvement". My goal was to start with the NIST 2015 LWB design that had a reported error of 1%, and modify it to reduce the error to 0.1%, while preserving the original NIST LEGO design as much as possible, and keeping the costs low and the technology within the range available to any amateur scientist. I will include my performance data, as well as sources and costs for parts, and recommendations for future improvements. Modifications include:

  • 1. How to find all the Legos needed for the LWB
  • 2. Constructing a base for the LWB
  • 3. Vibration damping for the LWB
  • 4. Eliminate tensions from moving wires by making coils stationary and allowing magnets to move
  • 5. replace plastic balance LEGO plastic pivot with polished carbide rods
  • 6. replace shadow sensor laser based height calibration with 0.001mm (1um) micrometer
  • 7. replace high friction balance arm LEGO pivots by single lower friction LEGO universal joint.
  • 8. add photodiode amplifier to match ADC range to photodiode output
  • 9. add heatsink for laser diode and photodiode to improve temperature stability
  • 10.add light shield for photodiode to reduce pickup from room lighting.
  • 11. calibrate mass weights with 0.1% accuracy @ 10 grams (~0.01 grams).
  • 12. add temperature gauge to determine if temp changes during measurements
  • 13. calibration check for NI 6001 using inexpensive current/voltage calibration device.
  • 14. replace 0.1% resistors for current sense and opamp gain resistors.
  • 15. add construction details of vibration isolation platform.
  • 16. add construction details of enclosure to shield from air motion. .
  • 17. add ampifier to match current sense resistor voltage to ADC voltage range.
  • 18. add LEGO structure modifications to increase rigidity.
  • 19. add suggestions for changes in NIST measurement software.
  • 20. add revised measurement steps with video.
  • TBD (each of above items should link to it's own web page)

    THIS WEB PAGE UNDER CONSTRUCTION - JUNE 2020

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• FEEDBACK
  Please any suggestions or corrections to this web page.
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• SOME OF MY OTHER INTERESTS
  • View My Real-Time Infrasound Monitor
    * click on image to enlarge display - this monitor is located in Waynesboro, VA
    * display shows last 24 hours, updates every 5 minutes, generated by AmaSeis seismic software
    * each horizontal line shows 1 hour of infrasound intensity, hours on left axis are in Universal time
    * most recent infrasound data is at bottom, oldest data is at top
    * microbarograph type sensor, filtered bandwidth is 0.05 Hz to 20 Hz, resolution is 0.001 Pascals
    * this display typically shows infrasound from freight trains, spikes from door opemings, and wind noise.
    * This Infiltec Model INFRA20 Infrasound Monitor is available from eBay or Amazon
    
    
    
    
    

  • View My Real-Time Seismograph
    * click on image to enlarge display - this seismometer is located in Waynesboro, VA
    * display shows last 24 hours, updates every 5 minutes, generated by AmaSeis seismic software
    * each horizontal line shows 1 hour of seismic data, hours on left axis are in Universal time
    * most recent seismic data is at bottom, oldest data is at top, scrolls upward hourly
    * sensor is a 4.5 Hz vertical geophone, filtered bandwidth is 0.04 Hz to 0.08 Hz
    * sensitivity ~ detects quakes ~M3+ @ 60miles(100km), ~M6+ @ 3k miles(5000km), ~M7+ @ 10k miles(17000km)
    * This Infiltec Model QM-4.5LV Seismometer is available from eBay or Amazon
    
    
    
    
    

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  This page copyright © 2020 by , all rights reserved. It was last updated on June 22, 2020.