i 've been wondering how do the electronic weighing machines work...... like how do they measure the weight of an object..... may be its a mechanical process bt how do they display that weight on an LCD or 7 segments.... anyone has any idea???

 

Maybe a variable resistor which varies as more weight gets on the scale, then a microcontroller with a built-in ADC to control the LCD.

 

They use a load cell (or several) under the platform. For lab balances, a servo controller maintains the platform at a fixed position by regulating current through a coil that reacts against the field of a magnet.

 

i 've been wondering how do the electronic weighing machines work...... like how do they measure the weight of an object..... may be its a mechanical process bt how do they display that weight on an LCD or 7 segments.... anyone has any idea???

There are many ways of doing this, but one of the most accurate is with a load cell. This is a bar of linearly elastic material (such as a steel wire or rod) with a resistance wire tightly bound to it. As the rod stretches, the resistance wire does also, increasing its resistance. (In some heavy industrial applications, the resistance of the elastic bar itself is measured)

Eric

 

Hello,

Here is a little description of a load cell.
http://www.rdpe.com/ex/hiw-sglc.htm

This link comes from the EDUCYPEDIA page on displacement sensors.
http://www.educypedia.be/electronics/sensorsdis.htm

Greetings,
Bertus

 

I had a "digital" bath room scale. The weighing mechanism was the same old spring/level/gear system as in the rotating-dial "analog" scales, except the dial had radial stripes. This, with a photo-coupler, fed a quadrature decoder and up/down counter that drove the digital display. Yeah, real digital accuracy.

Ken