Load Cell Development
Actually,Weighing techniques predate recorded history. The first bonded resistance wire strain gage was developed in the 1940s, it was not until modern electronics caught up that the new technology became technically and economically feasible. but just 40 years ago, the fundamentals remained virtually unchanged.
The key discovery was made in 1939 by two researchers who were working without knowledge of each other, Arthur Ruge of the Massachusetts Institute of Technology and Edward E. Simmons at the California Institute of Technology. They found that a piece of tungsten filament, such as is commonly used in a light bulb, can be placed in a device known as a Wheatstone bridge and used to measure strain on a metal. The strain is proportional to the weight of the object causing the strain.
The Wheatstone bridge is, in essence, four resistors wired in a diamond shape. When electrical current is run across the diamond on the filament, there is no voltage output if the symmetry of the diamond is undisturbed. If on the other hand some force has disturbed the symmetry, the resistors produce a voltage flow proportional to the disturbance.
Housed in a casing, the strain gauge is today called a load cell. In the last decade, according to scale manufacturers, it has all but eliminated the market for most mechanical systems. Weighing with electricity helps scale makers to exploit the advantages of modern electronics. The result is smaller scales that read weights faster with greater accuracy. The manufacturers also cite maintenance savings with the reduction in the number of moving parts.
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