USB Oscilloscope Accuracy???

[rado_1]

Hello Everybody! 
I Watch EEVblog channel on YouTube for some years now, but im new here i this forum. First excuse me for my English it is not my native language and 2nd: electronics is just my hobby, im not engineer or geek im just a noob!  Anyway this is my question:

I have a Chinese bu***it oscilloscope "Instrustar".... ( I know  , my budget was limited  ) and for some time now i was wondering if this scope is accurate. I made a photo of the screen with the data from an Arduino on pin 4, this is the simple code i use:

Code: [Select]

void setup() {
  
  pinMode(4, OUTPUT);

}

void loop() {
  digitalWrite(4, HIGH);   
  delay(100);              
  digitalWrite(4, LOW);    
  delay(100);    
         
}

and this is the data from the scope:




If someone of you have good oscilloscope and Arduino can u pls make the same test and send me the result to compare it, a least to know if this junk does the job for simple projects.  If not to trash it and to buy an RIGOL.... 

Thx... 
 

[cncjerry]

I happened to have an arduino uno sitting here and I was playing around with my old Tektronix TDS744a which has been upgraded to a TDS784A and thought, what the hell, here you go.  The low res BMP doesn't do the display justice.  I was also using an active probe, P6205, which I don't have a lot of time on but it maps at least by frequency to your scope.  The variance in voltages could easily be due to the USB port as I was using a mac.

[Dave]

What exactly is wrong with the graph in the first image? Looks fine to me. 

[rado_1]

I happened to have an arduino uno sitting here and I was playing around with my old Tektronix TDS744a which has been upgraded to a TDS784A and thought, what the hell, here you go.  The low res BMP doesn't do the display justice.  I was also using an active probe, P6205, which I don't have a lot of time on but it maps at least by frequency to your scope.  The variance in voltages could easily be due to the USB port as I was using a mac.

Thank you my friend. So from what i see my 70$ scope does the job for now. 

[rado_1]

What exactly is wrong with the graph in the first image? Looks fine to me. 

I was just to compare my junk skope with some normal scope. 

[Rick Law]

Hello Everybody! 
...
If someone of you have good oscilloscope and Arduino can u pls make the same test and send me the result to compare it, a least to know if this junk does the job for simple projects.  If not to trash it and to buy an RIGOL.... 

Thx... 

Junk is something that cannot do any productive job for you.  Your scope shown the square wave well.  A lot of noise, yes; but that is a problem for any scope and it is just a matter of degree.

However good a scope and however expensive a scope, there will be something that expensive scope couldn't do (and other more expensive one might...)

If the scope is helping you, then for you, it is not junk.  If you need see something that the scope cannot show, it has a short coming - that still doesn't make it junk if it helps you.

I use a low price USB scope (Hantek 6022BE).  I would like a more capable scope, but I cannot cost-justify it.  Junk for some, but useful to me.