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need an oscilloscope on a very low budget

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hello dear friends
I want to make a web site about cables and chargers for cell phones like apple,Samsung and etc.
As you know modern phones use switched-mode power supply chargers capable of power delivery or quick charge and other fast charge standards.
I wanted to review such chargers, specially their output quality ,parameters like ripple and noise that need an oscilloscope.
I live in Iran and everything is very pricey under heavy sanctions and I have about 60 dollars budget .so I can buy hantek PSO 2020.
Do you think this oscilloscope can measure ripple and high frequency noise well enough considering that switching frequency of modern chargers is very high?
Is the sampling rate enough? if I am right the true sampling rate of this model is 48ms not 96ms.maybe even lower.
What about the bandwith do you trust the hantek in that regard?
There is also hantek 6022BE with two channels and no ac coupling . don’t know if that is a better option.
I found some owon models for about 2 to 3 times the price and I could not afford them.
Do you think I must save more money and buy one of them? i mean owon rds 1021 or 1022.
My most important need is to verify if the chargers output good quality dc current for the phones. if you think that I have to measure other parameters other than ripple and noise please notify me.
Thank you all .

Note that m is an abbreviation for milli which is a thousandth (1/1000) whereas M is an abbreviation for Mega which is a million (1,000,000).

I would also build an electronic load, prefferably variable. Using phone as a load is not very scientific and may lead to various inaccuracies. Decent multimerer is a must for accurate voltage measurements. You may want to measure voltage at maximum load. That indicates cable quality (voltage drop). Crappy cables might drop a lot, which is also a sign that they are likely less mechanically robust and may break easily.

Now the noise measurement is more difficult. I recommend you to study the subject. You should use ground spring, not ground clip. It will depend what point you probe. Probably you want some nominal bypass capacitor directly at probing point. You might want to use common mode filter, because your measurements may get polluted by common mode noise. Is 20Mhz bandwidth enough? Borderline. 20mV per division is certainly not very sensitive. Is it on 10X or 1X? If it is 1X, then at 10X it will be 200mV per division, beware!

I would also test isolation voltage of the chargers. This would be destructive and requires special equipment. But knowing that cheap chargers regulary shocks and kills people, that is really relevant test.

Thank you.very helpful points .what about oscilloscope models i mentioned or any other suggestions?


--- Quote from: sx57 on December 05, 2022, 08:24:30 am ---Thank you.very helpful points .what about oscilloscope models i mentioned or any other suggestions?

--- End quote ---

Probably want to stay away from some models.
Look for the thread in the Test Equipment section with title "What brand name oscilloscope" or something like that there is a big discussion about scopes and that some are not very good.

Here it is:


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