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