Tuesday, August 17, 2010

How does a Digital Weigh Scale work?

Imagine you pick an apple and try to guess it's weight. You would place it in your palm and toss it lightly to feel the weight. After 3 or 4 tosses you would say "200 grams". Your hand sensed the weight and sent a signal to your brain which after some calculations estimated the weight. Right? Similarly, when you place the same apple on a digital weigh scale, the load cell senses the weight and sends the signal to the indicator. The signal conditioner processes the load cell signal and displays weight.

Basically all weigh scales consist of-
  • a structure
  • one or more load cells
  • signal conditioner

Structure is the load bearing part. It transfers the weight to the load cell(s). In low capacity scales (table-top/bench/platform) the structure houses the load cell and electronic components. In higher capacity scales (floor/dormant/weigh bridge) the structure rests on load cells. The weight indicator

Load Cell is basically a transducer which converts force into electrical signal. Every digital weigh scale has one or more load cells. Table-top/Bench/Platform scales are single load cell weighing machines. Floor/Dormant scales have four load cells. Truck scales or Weigh bridges have 4 to 8 load cells depending on the rated capacity and length of the bridge. For all scales load cell is the part which determines the scales rated capacity. Of course the mechanical structure is designed to withstand loads well beyond the rated capacity. Load cells capacities range from 500g to 100T.

Signal Conditioner is the electronics part, it powers the load cell, receives signal from the load cell(s) and converts that signal to readable numbers. The numbers- digital output- can be made to display in desired unit of weight. Signal conditioners have extended features like RS232 or 4-20MA output which can be used for data acquisition or control other electrical equipment. An electronic weigh scale hooked up to a computer can automate many aspects of business operations like materials management or process control or billing automation.

Compare a mechanical scale to an electronic scale. Mechanical scale just shows the weight but an electronic scale does much more than that- it helps automate.


1 comment:

  1. hi, siddeshwar, this one is the best post i have seen on working of a Digital weighing scale. Thanks for sharing this article.