Strain gauge amplifiers

Strain gauge amplifiers often prove indispensable for the processing of signals from force meters. They generate the pulses from which the control unit can determine the exact measured value.

The output signals generated by load cells and other strain gauges normally represent the resistance as modified by the deformation of the wire or foil. This information is however difficult to interpret for the control unit and must therefore be translated into electric pulses. This task is performed by the strain gauge amplifier, which is also known as a weighing transmitter. Certain load cells are equipped with fully integrated strain gauge amplifiers that convert the measured resistance into current and voltage pulses. In most cases, the output signal of the strain gauge sensor is however converted by an external amplifier. This approach has the advantage that the control unit can be installed away from the sensor, as the amplified signals can travel a much longer distance. Read more...

Scope of strain gauge amplifiers

Depending on the type, strain gauge amplifiers come with several separate signal inputs to which the individual strain gauges are connected. The most common configuration is 4 to 6 inputs for 4 to 6 load cells. The amplifier generates the electric pulses that are then translated by an A/D converter and sent to the control unit. External amplifiers enable operators to adjust the output signal to the required format, which is one of their main advantages. Display modules and PCs can be controlled by means of measuring software through RS485 interfaces. The analogue output signal can be processed by a PLC unit. Some amplifiers provide signals suitable for field bus systems such as Profibus and ProfiNet.


Summary and conclusion

Strain gauge amplifiers do not only make the measurements from the strain gauge available to the control unit in a format that suits its logic, they also allow for the integration of strain gauges into bus systems. In addition, they can transmit signals over larger distances, so that the measurements can be processed by evaluation systems located away from the actual weighing or force measuring equipment.