Solving Interference Issues in Circuit Testing

In summary, the conversation discusses the issue of interference between circuits when running a large current through a material at intervals for heating and resistance measurements. The individual circuits are not an issue, but it is necessary to address the interference between them. The question is whether putting a power transistor on each series of connections would suffice, or if something more complicated is needed. The possibility of doing both actions simultaneously, measuring current and voltage while heating the material, is also raised. However, concerns are raised about potential differences in voltage drop and the use of relays with average switching speeds of a few milliseconds.
  • #1
scott_alexsk
336
0
Hello,

I am making a circuit which runs a large current through a material at intervals, heating it, which then temporarily stops to make a resistance measurement. Each individual circuit is not an issue in itself, nor the timing of it since I have a computer interface which can grab analog values and produce digitial 1s.

The issue I need to address is the interference of each circuit's operation with the other's. Do I need to just put a power transistor on each series of connections to the material I am testing for each part of the circuit, or do I need to do something more complicated?

So in other words can I just, let's say, turn on the circuit which measures resistance, by providing an appropriate input to that transistor(or FET) and turn off the section which provides the heating current by providing another input to the other controlling transistor, without the heating circuit significantly interfering with the measuring circuit or vice-versa?

Thanks,
-Scott
 
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  • #2
Can you just do both simultaneously? Can you measure current and voltage being applied to the material as you are heating it?
 
  • #3
Well wouldn't that the changing current from my heating circuit, cause the voltage drop to be different across the material, which would in turn provide a different value than expected for my four-wire kelvin circuit, which is simultaneously hocked up to the material. Perhaps I can use relays, what is the average switching speed on those guys?

Thanks,
-Scott
 
  • #4
scott_alexsk said:
Well wouldn't that the changing current from my heating circuit, cause the voltage drop to be different across the material, which would in turn provide a different value than expected for my four-wire kelvin circuit, which is simultaneously hocked up to the material. Perhaps I can use relays, what is the average switching speed on those guys?

Thanks,
-Scott

Small relays bounce for a few ms, typically.
 

What is interference and how does it affect circuit testing?

Interference in circuit testing refers to any unwanted signals or disturbances that can disrupt the proper functioning of a circuit. This can be caused by external factors such as electromagnetic waves, power supply fluctuations, or nearby electronic devices. Interference can affect the accuracy and reliability of circuit testing results, making it important to address and eliminate it.

What are some common types of interference encountered in circuit testing?

Some common types of interference encountered in circuit testing include crosstalk, ground loops, and electromagnetic interference (EMI). Crosstalk is when signals from one circuit interfere with signals in another circuit. Ground loops occur when there is a difference in ground potential between two points in a circuit, causing unwanted current flow. EMI is caused by external sources such as power lines, radio waves, and other electronic devices.

How can interference be minimized during circuit testing?

Interference can be minimized by using proper shielding and grounding techniques. This includes using shielded cables, isolating sensitive components, and ensuring proper grounding of all components. Additionally, keeping the circuit testing area free from other electronic devices and sources of EMI can also help reduce interference.

What are some troubleshooting methods for interference issues in circuit testing?

If interference is still present in circuit testing, there are several troubleshooting methods that can be used. This includes using a spectrum analyzer to identify the source of interference, using filters to eliminate unwanted signals, and adjusting the circuit layout to minimize crosstalk and ground loops. It may also be beneficial to test the circuit in different environments to see if the interference is location-specific.

How important is it to address interference issues in circuit testing?

Addressing interference issues in circuit testing is crucial for ensuring accurate and reliable results. Interference can lead to false readings, improper functioning of the circuit, and even damage to components. Therefore, it is important for scientists and engineers to identify and eliminate interference to ensure the proper functioning of circuits and the success of experiments and projects.

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