A load cell is referred to as a sensor device that is used to determine an applied physical force and then transform that force into an output that is directly proportional to the force. There are many kinds of load cells. They are hydraulic, pneumatic, capacitive, strain gauge etc. Strain gauge is the most commonly used type of load cell.
It produces an electrical voltage signal that is proportional to the applied force. But the output signal is very small in magnitude. Most of the load cell circuits are installed in a Wheatstone bridge configuration which is a simple circuit useful for measuring an unknown resistance. The strain gauge sensitivity is rated in mV/V denoting that the maximum output is a function of the excitation voltage. Learn about plug and play smart load cells here.
These electronic devices are built from parts designed to amplify the small output signal of the load cell signal conditioning in the presence of large common mode voltage signals. There are two types of amplifiers: operational and instrumentation. The former is call op amp which is the most crucial one. They are used in signal conditioning system for amplifying, filtering and performing some mathematical calculations.
Filtering means elimination of undesirable electrical noise that hinders the load cell output signal. The noise can be electromagnetic interference from the adjacent equipment or other parts, particularly if the load cell output signal is routed via a printed circuit board. The unwanted signals are the undesirable frequencies, so they enact like AC signals. There are many classes, categories and kinds of filters. But the common ones are:
- Low pass filter: Pass low frequencies, reject high frequencies
- High pass filter: Pass high frequencies, reject low frequencies
- Bandpass filter: Pass a narrowband of frequencies
- Band-rejection filter: Reject a narrowband of frequencies
Functions of sensors output signal
To conclude this article, we have listed the important functions of sensors output signals. They are as follows:
- It shields other parts of the overall system by having a control over the output current or voltage signals.
- It converts the sensors output signal into a voltage/current level that can be easily processed by other digital parts of the system.
- It also helps in attenuating or filtering off the ground noises or other electrical noises from the adjacent equipment.