Choosing an Oscilloscope

How to choose an oscilloscope [Things to consider]

Hay, hope you are doing fine. An oscilloscope is a very basic tool in every electronics professional’s lab. Your lab is incomplete with it. So pay close attention when you are choosing an oscilloscope.

There are so many reasons you should have your own oscilloscope if you want to play around electronics. Let me just take a very small example. You need an oscilloscope to see the out of an amplifier, to compare how much it has been amplified. You just can’t go performing this task without having your own scope in your lab.

I think you got my point here. As important this tool is, so as its selection. You must have your research done before investing any money on it.

In this post, I try to give you some guidance that you need in the selection of an oscilloscope for yourself.

Hopefully, you will enjoy this post.

Selection of the best oscilloscope

I think the selection is the most important thing to pay close attention to. I try to explain everything in a very simple possible language.

So, don’t worry. Just grab a piece of paper, a pencil, and a calculator. Answer all the questions I ask on the paper. By doing so you will have a rough model of your desire best beginner oscilloscope at the end.

Alright!

The selection of oscilloscope depends on a lot of things and parameters. Before jumping into parameters explanation and questions, which I have done in my other post, the first step is to answer the following questions.

Write all your answers on the paper.

  • For what situation you need a scope i.e. where you are to use it. For example on the bench, at a customer’s site, under the hood of your car.
  • How many signals do you want to measure at once? For example, how many measuring channels you will require in your scope.
  • A guess of frequencies you will measure with the scope. According to me, you should be very sure of your frequency range to be measured by the scope. This question is very important, please pay very close attention to it. The wrong answer can cause you wastage of money.
  • What are the amplitudes of your signals? In case you don’t know, leave it. It is ok.
  • Are the signals you are going to measure periodic or non-periodic?

I am supposing you took the above question seriously and wrote down your answers.

A bench scope is a little heavy and specific for more professional work at the lab. If you are going to use your scope in the field, or for car diagnosis, you need a portable one. Which is of course not too heavy, but is not as professional as the bench. The bench scope is relatively more expensive than the rest.

Coming towards the technical questions. At this point, some of you may get bored. But I am just trying to save you from wasting your money. This is my only intention here.

Alright!

How much bandwidth you will require?

This is the most important question. Please pay close attention here. Because if you mess with this one, you may lose a lot of money.

The answer to this is, multiply you highest frequency with 5.  For example, if your highest measuring frequency is 10MHz, then the ideal beginner oscilloscope for you is with bandwidth 50MHz.

The more bandwidth is not an issue. Like for the said highest frequency you can also use a scope with 100MHz bandwidth, but it is not a good idea. Because it will cost you more money and most importantly if you are not professional you will end in getting a high noise floor as well.

If you are thinking you are not sure of the future. like you want to buy high bandwidth because you are not sure of the signals you will deal in future. Then let me tell you oscilloscopes have bandwidth upgrade options for less cost. You can upgrade the bandwidth in future if need it.

For those who want to learn bandwidth in more detail, I explain it in my other post (you will find the link below, or you search it through search bar).

How much sample rate you will need?

Next to bandwidth, the second thing to consider in choosing an oscilloscope is the sample rate.

The answer to this question is The Nyquist criterion which states that the sampling rate must be at least twice the maximum frequency that you want to measure.

For example, if your maximum frequency is 10MHz then the ideal scope for you must have a sample rate of 20MS/s.

Again higher sample rate will end in costing more money.

Analysis of random signals, to capture the random and infrequent signals or glitches?

Are your projects will involve the investigation of glitches? By glitches, I mean the small random impulsive signals that cause the sudden failure of  a system.

If yes, then select the one with high waveform capture rate and high memory depth.

The high waveform capture, as the name indicates, captures a small signal with no time waste. And by high memory depth, it is saved for our analysis. So, the end story is, for more professional diagnosis, you need a scope with high memory depth as well as a high wave capture rate.

The high wave upgrade can be plus point here, but it is not available, still, things are pretty fine.

For those who want to learn memory depth in more detail, I explain it in my other post (you will find the link below, or you search it through search bar).

What resolution and accuracy you need?

By resolution in an oscilloscope, we mean the resolution of its ADC. With eight-bit resolution, you can detect at best a 0.4% signal change. For applications such as audio, noise, vibration, and monitoring sensors (temperature, current, pressure), an eight-bit oscilloscope is often not suitable, so you should consider 12 or 16-bit alternatives. (Source: Nutsvolts)

With a higher resolution oscilloscope, more accurate measurements are possible.

Above are the must answer questions. I hope you took them seriously.  Now, if you didn’t leave the post and still reading 😀

let’s go further.

For me, the following are the must in beginner oscilloscopes.

  • Come from a trusted brand, if you buying a non-branded thing possibility is, you are going to lose your money in the long term
  • Must be of a decent price, so a beginner can afford it. But this doesn’t mean there should be any compromise on its quality
  • It should fulfill all the tasks/requirements for which an oscilloscope is designed
  • It must have a decent bandwidth range, sample rate, memory depth, and wave update rate
  • It should feel good
  • It must be very easy to use, don’t need to use a guide

Final words

Choosing an oscilloscope may seem easy, but it is not. There are a lot of things you need to consider before investing any money in it.

For example, the price for oscilloscope is directly proportional to the value of bandwidth and sample rate. The high the mentioned parameter, higher the price.

So, care should be taken before buying an oscilloscope. You must have answered some questions like for what situation you need it, what is your measuring signals and few more explained in the above post.

Hopefully, I was some kind of help to you.

Thank you and have a good life.


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