Wheatstone bridge offset-nulling circuit

In summary, the conversation is about creating a cantilever beam measurement system using two strain gauges. The system will need to be nulled before adding any weight, possibly by using a variable resistor. The resistance of the strain gauges will need to be measured to determine the necessary values for the fixed resistors.
  • #1
nitronick
1
0
Hi all, I’m making a simple cantilever beam measurement system using 2 strain gages (120Ω).

The two gages make up one leg of my Wheatstone bridge; the other leg will be made up using 120Ω resistors.

Because of tolerances etc I will need to null the system before I add any weight to the end of the beam.

So how is best to go about this, I’ve been looking about on Google but all I can find is to add a variable resistor into the circuit, but I’m not sure where and what value to use.

Any help will be much appreciated.
 
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  • #2
Probably about 2x the tolerance of your devices. You're mostly nulling-out the error, which is the difference in the response of the two sensors and any temperature related fluctuations. But an experiment might be the best way to figure it out...
 
  • #3
You could start by measuring the actual resistances of the strain gauges. If there is a difference of n% then the two fixed resistors could be picked to have the same ratio. Only a small value of variable resistor would be necessary then. But the numbers would depend on what your measurements tell you.
 

Related to Wheatstone bridge offset-nulling circuit

1. What is a Wheatstone bridge offset-nulling circuit?

A Wheatstone bridge offset-nulling circuit is a type of electronic circuit that is used to measure small changes in resistance. It consists of four resistors arranged in a diamond shape with a power source connected at the top and a voltmeter connected at the bottom. The circuit is designed to balance out any offset voltage, or unwanted voltage, in order to accurately measure the resistance of a sensor or a component.

2. How does a Wheatstone bridge offset-nulling circuit work?

A Wheatstone bridge offset-nulling circuit works by using a null detector to measure the difference in voltage between two points in the circuit. If the voltage difference is not zero, the circuit will adjust the resistance of one of the resistors until the voltage difference becomes zero. This process is known as nulling, and it ensures that the circuit is balanced and ready to accurately measure the resistance of a sensor or component.

3. What are the applications of a Wheatstone bridge offset-nulling circuit?

A Wheatstone bridge offset-nulling circuit is commonly used in electronic measurements, such as strain gauge measurements, thermistor measurements, and resistance measurements. It is also used in industrial and scientific instruments, such as pressure sensors, flow meters, and gas sensors. Additionally, the circuit can be used in precision instrumentation and control systems.

4. What are the advantages of using a Wheatstone bridge offset-nulling circuit?

One of the main advantages of a Wheatstone bridge offset-nulling circuit is its ability to accurately measure small changes in resistance. This makes it useful in applications where high sensitivity is required. Additionally, the circuit is relatively simple and inexpensive to construct, making it a popular choice for many electronic measurement systems.

5. Are there any limitations to using a Wheatstone bridge offset-nulling circuit?

Although a Wheatstone bridge offset-nulling circuit has many advantages, it also has some limitations. One limitation is that the circuit can only measure resistances that are within the range of the resistors used in the circuit. Additionally, the circuit may be affected by external factors such as temperature changes, which can alter the resistance of the components and affect the accuracy of the measurements. It is important to properly calibrate and maintain the circuit in order to ensure accurate measurements.

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