The Wheatstone measuring bridge (also known as a Wheatstone bridge) is an electrical bridge circuit used for highly accurate measurements of resistance and minute changes in resistance. It is used in particular in applications where quantities such as force, strain, pressure, or weight can be measured as minute changes in resistance.
Among the most important areas of application are Strain Gauges (SG), force transducers, load cells, and pressure sensors.
How the Wheatstone Bridge Works
The Wheatstone bridge consists of four resistors connected to form two voltage dividers. Between the two arms of the bridge is the so-called Bridge voltage or Differential voltage measured.
When the system is balanced, the following applies:
- The ratio of the resistances of the two branches is identical.
- There is no potential difference between the midpoints of the bridge.
- The measured voltage difference is 0 volts.
If one of the resistors changes, a voltage difference is created that is proportional to the change in resistance.
This change can then be analyzed in detail.
Setting Up a Wheatstone Bridge
A classic Wheatstone bridge consists of:
- Four resistors
- A supply voltage
- A measurement circuit for detecting the differential voltage
The resistors form two opposing bridge arms:
Plain Text
+ Power Supply
|
R1 R2
|——|
| |
R3 R4
|
– Power supply
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The differential voltage is measured between the two middle nodes.
Wheatstone bridge with strain gauges (SG)
The Wheatstone bridge is used particularly often in conjunction with strain gauges.
A strain gauge changes its electrical resistance when it:
- is stretched,
- is compressed, or
- is subjected to mechanical forces.
Since these changes in resistance are usually very small, the Wheatstone bridge allows for their highly precise measurement.
Typical applications are
- Force Measurement
- Weight Measurement
- Pressure Measurement
- Material Testing
- Structural Monitoring
- Test Bench Technology
Bridge Circuits in Measurement Technology
Depending on the number of active sensor elements, different bridge configurations are used:
Quarter Bridge
- An active DMS
- Simple Setup
- Cost-effective
Half-bridge
- Two active DMSs
- Higher sensitivity
- Improved temperature compensation
Full bridge
- Four active DMSs
- Maximum Sensitivity
- Highest Measurement Accuracy
- Excellent temperature stability
The full-bridge circuit is frequently used in industrial force transducers and load cells.
Advantages of the Wheatstone Bridge
The bridge circuit offers numerous advantages:
- High measuring accuracy
- Detection of the slightest changes in resistance
- Good immunity to interference
- High sensitivity
- Temperature compensation is possible
- Ideal for DMS applications
- A proven measurement principle in industry and research
That is why the Wheatstone bridge remains one of the most important measurement methods in sensor and testing technology to this day.
Wheatstone Bridges in Delphin Measurement Systems
The measurement data acquisition solutions from Delphin Technology support the acquisition of a wide variety of sensor signals, including strain gauge-based transducers for force, pressure, and strain measurements. The systems are designed for precise measurement tasks in laboratories, test benches, and industrial applications, and enable the reliable acquisition and evaluation of even the smallest changes in measurement signals.
The Expert Logger 100 can supply power to Wheatstone bridge circuits. The resulting bridge voltage—or differential voltage—is measured and evaluated relative to the supply voltage. This allows even very small changes in resistance to be determined precisely, such as those that occur in strain gauges or force sensors.
Typical Applications
Wheatstone bridges are used in:
- Strain Gauges (SG)
- Force sensors
- Load Cells
- Pressure transducers
- Material Testing Machines
- Test benches
- Mechanical engineering
- Automotive Engineering
- Research and development
- Structural and Condition Monitoring
Why is the Wheatstone bridge important?
Many physical quantities can only be measured through minute changes in resistance. The Wheatstone bridge enables these small changes to be reliably converted into precise, measurable voltage signals.
As such, it forms the basis for numerous modern sensors and measurement methods and has become an indispensable part of industrial measurement technology, test bench technology, and sensor technology.