Load cell

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A single-point load cell

A load cell is typically an electronic device (transducer) that is used to convert a force into a differential electrical signal. This device normally consists of four strain gauges in a wheatstone bridge configuration, but are also available with one or two strain gauges. The electrical signal output is normally in the order of a few millivolts and requires amplification by an instrumentation amplifier before it can be used. The output of the transducer is plugged into an algorithm to calculate the force applied to the transducer.

Although strain gauge load cells are the most common, there are other types of load cells as well. Hydraulic (or hydrostatic) is probably the second most common, and these are utilized to eliminate some problems with strain gauge load cell devices. As an example, a hydraulic load cell is immune to transient voltages (lightning) so might be a more effective device in outdoor environments. Other types include piezo-electric load cells (useful for dynamic measurements of force), and vibrating wire load cells, which are useful in geomechanical applications due to low amounts of drift.

During operation, "load cell ringing" can occur. This vibration of the load cell occurs when the load cell is subjected to a relatively high force. An oscillating data pattern can be the result.