How to Use a Lock-In Amplifier for Johnson Noise Experiments

In summary, The conversation discusses the use of a Lock In Amplifier for a Johnson Noise experiment, and the question of whether a book or website exists that thoroughly explains its usage. The discussion also touches on the concepts of low pass filters and roll off in Lock-in amplifiers and when it may be preferable to use a lower order filter.
  • #1
JamesJames
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Is there a book or website that explains throughly how to use a Lock In Amplifier? I have never used one before and am using it in a Johnson Noise experiment with the "Art of Experimental Physics by Preston and Dietz" acting as the lab manual.
 
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  • #2
http://www.cpm.uncc.edu/programs/tn1000.pdf [Broken]
 
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  • #3
help

Dear all,

I understand the meaning of low pass filter and roll off in Lock-in amplifiers (I think at least). Pratically, the 24db/octave roll off should be better for a grater signal to noise ratio.

So. why there is the possibility to use lower order filters? When I should prefere a 6db/octave filter?

thank you all for help
 

1. What is a lock-in amplifier and how does it work?

A lock-in amplifier is an electronic instrument used to measure small signals buried in noise. It works by using a reference signal to demodulate the input signal, making it easier to distinguish the desired signal from the noise.

2. How do I set up a lock-in amplifier for Johnson noise experiments?

To set up a lock-in amplifier for Johnson noise experiments, you will need to connect the input signal (typically from a resistor) to the lock-in amplifier's input, and the reference signal (usually from a function generator) to the reference input. You will also need to set the correct input and reference frequencies, as well as the time constant and filter settings.

3. Can a lock-in amplifier be used for other types of noise measurements?

Yes, lock-in amplifiers are commonly used for various types of noise measurements, including shot noise, thermal noise, and 1/f noise. However, the setup and settings may vary depending on the type of noise being measured.

4. What are the advantages of using a lock-in amplifier for Johnson noise experiments?

The main advantage of using a lock-in amplifier for Johnson noise experiments is its ability to significantly reduce the effects of noise, allowing for more accurate and precise measurements. It is also a relatively simple and versatile instrument that can be used for various types of noise measurements.

5. Are there any limitations to using a lock-in amplifier for Johnson noise experiments?

While lock-in amplifiers are very effective at reducing noise, they are not able to completely eliminate it. This means that the accuracy of the measurements is still dependent on the quality of the reference signal and the noise level. Additionally, lock-in amplifiers may not be suitable for measuring extremely low frequency noise or signals with a high dynamic range.

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