Micro Load Cell (Weight Sensor) with 50kg Capacity

A load cell is a force sensing module that consists of a well-built metal structure with small strain gauges installed in exact positions. Load cells are made to measure a single force and ignore any other forces that may be present. The load cell's electrical signal is relatively tiny and requires specialized amplification.Fortunately, the 1046 Phidget Bridge will handle all of the electrical output amplification and measurement. Load cells are designed to measure force in one direction. They will often measure force in other directions, but the sensor sensitivity will be different, since parts of the load cell operating under compression are now in tension, and vice versa

Working

Load cells with strain gauges translate the force imposed on them into electrical impulses. Strain gauges, which are essentially small, flexible circuit boards, are used to measure the resistance patterns. The strain gauges are bonded to a beam or structural part that deforms when weight is applied, causing the gauge to deform as well. The electrical resistance of the strain gauge changes in proportion to the load as it is deformed.

The changes to the circuit caused by force are much smaller than the changes caused by variation in temperature. Higher quality load cells cancel out the effects of temperature using two techniques. By matching the expansion rate of the strain gauge to the expansion rate of the metal it’s mounted on, the undue strain on the gauges can be avoided as the load cell warms up and cools down. The most important method of temperature compensation involves using multiple strain gauges, which all respond to the change in temperature with the same change in resistance. Some load cell designs use gauges that are never subjected to any force but only serve to counterbalance the temperature effects on the gauges that measure force. Most designs use 4 strain gauges, some in compression, some under tension, which maximizes the sensitivity of the load cell, and automatically cancels the effect of temperature.

Installation

Small jewellery scales and kitchen scales uses this Single Point Load Cell. It's mounted by fastening down the wire-attached end of the load cell and exerting force in the direction of the arrow on the other end. Because this load cell measures a shearing effect on the beam rather than bending, it doesn't matter where the force is delivered. When a small platform is mounted on the load cell, as in a small scale, the load cell produces precise measurements independent of the load's position on the platform.

Calibration

A simple formula is usually used to convert the measured mv/V output from the load cell to the measured force:

Measured Force = A * Measured mV/V + B (offset)

It’s important to decide what unit your measured force in - grams, kilograms, pounds, etc.

This load cell has a rated output of 1.0±0.15mv/v which corresponds to the sensor’s capacity of 50kg.

Since the Offset is quite variable between individual load cells, it’s necessary to calculate the offset for each sensor. Measure the output of the load cell with no force on it and note the mv/V output measured by the PhidgetBridge.

Offset = 0 - 50 * Measured Output