How Digital Scales Work


Lots More Information

Author's Note: How Digital Scales Work

One of the joys of writing for HowStuffWorks.com springs from encountering the surprising delicacy, beauty and complexity to be found in everyday objects. The deft engineering and intricately milled parts that go into these items are, alone, enough to inspire any technophile. Look beyond the appurtenances and appliances to the heart of any device -- particularly one used for measurement -- and you find something even more wondrous: a physical law, ingeniously harnessed to an array of specific and useful tools.

Nowhere is this truer than in scales. In this article alone, I encountered Hooke's law for springs; Pascal's law for fluid pressure; Boyle's law, Charles' law and Gay-Lussac's law describing the behavior of gases; and Ohm's law for electrical resistance -- and that's to say nothing of the various unnamed laws governing stress and strain.

So the next time you encounter some politician who wants to cut science education in the name of balancing the budget, it might be worth reflecting that our most enduring fiscal facilitators, scales, are made possible by a centuries-old march of scientific discovery.

Related Articles

Sources

  • American Weigh Scales, Inc. "Weighing Scale Terminology." 2011. http://www.awscales.com/support/terminology
  • Busch Electronics. "Understanding Melt Pressure Sensor Accuracy." http://www.buschelectronics.com/Pressure_Sensor_Accuracy.html
  • Camarda, Jennifer. Sales specialist, Sartorius Lab Products & Services. Personal correspondence. Feb. 5, 2013.
  • Cappella, B. and G. Dietler. "Force-distance Curves by Atomic Force Microscopy." Surface Science Reports. Vol. 34. Page 1. 1999. http://www.see.ed.ac.uk/~vkoutsos/Force-distance%20curves%20by%20atomic%20force%20microscopy.pdf
  • Cox, Fred. Vice president of sales, Cardinal Scale Manufacturing Co. Personal correspondence. Feb. 5, 2013.
  • Craig, James I. "Electrical Resistance Strain Gage Circuits." Resistance Strain Gage Circuits. http://soliton.ae.gatech.edu/people/jcraig/classes/ae3145/Lab2/strain-gages.pdf
  • Crowley, Ann. Product manager, Rice Lake Weighing Systems. Personal correspondence. Feb. 4, 2013.
  • Cumpson, Peter J., Charles A. Clifford and John Hedley. "Quantitative Analytical Atomic Force Microscopy: A Cantilever Reference Device for Easy and Accurate AFM Spring-Constant Calibration." Measurement Science and Technology. Vol. 15. 2004.
  • Eilersen Industrial Sensors. "Different Types of Load Cells and their Uses." 2010. http://www.eilersen.com/Different_Types_of_Load_Cells_and_their_Uses.html
  • Encyclopaedia Britannica. "Cupronickel (Constantan)."
  • Encyclopaedia Britannica. "Ancient Egypt."
  • Fairbanks Scales. "'Type S' Pit-Type Truck Scale." Brochure. http://www.fairbanks.com/documents/literature/100208.pdf
  • Mashaney, Derrick. Director, product development, Fairbanks Scales Inc. Personal interview and correspondence. Feb. 4, 2013.
  • National Institute of Standards and Technology. "Specifications, Tolerances and Other Technical Requirements for Weighing and Measuring Devices as adopted by the 96th National Conference on Weights and Measures 2011 (Handbook 44)." 2012 Edition. http://www.nist.gov/pml/wmd/pubs/upload/2012-hb44-final.pdf
  • National Instruments. "Strain Gauge Measurement – a Tutorial." Application Note 078. August 1998. http://www.ing.unp.edu.ar/electronica/asignaturas/ee016/anexo/r-an078.pdf
  • Omega Engineering. "Introduction to Load Cells." http://www.omega.com/prodinfo/loadcells.html
  • Petruso, Karl. "Early Weights and Weighing in Egypt and the Indus Valley." Museum of Fine Arts Bulletin (Museum of Fine Arts, Boston). Vol. 79. Page 44. 1981.
  • Plint, George. "System Accuracy." Phoenix Tribology. 2005. http://www.phoenix-tribology.com/cat/at2/index/system%20accuracy.pdf
  • Pratt, William F. "Strain Gage Measurement System – Fundamentals." http://www.suu.edu/faculty/pratt/spring04/engr2050/StainGageMeasurementSys.pdf
  • Sartorius AG. "The Fundamentals of Weighing Technology Terms, Methods of Measurement, Errors in Weighing." Brochure.
  • Sartorius Weighing Technology GmbH. "Correct Use and Handling of Analytical and Microbalances." Brochure.
  • Stefanescu, Dan Mihai. "Handbook of Force Transducers." Springer. 2011.
  • Takhirov, Shakhzod M., Dick Parsons and Don Clyde. "The 4 Million Pound Southwark-Emery Universal Testing Machine." Earthquake Engineering Research Center, University of California, Berkeley. August 2004. http://nees.berkeley.edu/Facilities/pdf/4MlbsUTM/4Mlb_Southwark_Emery_UTM.pdf

More to Explore