JohnBee

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Posts posted by JohnBee


  1. We've been deliberating what projects to implement in our homeschool classes to make good use of the our Discovery 2 kit. And I began to wonder if there were any walk-through type exercises that our children could follow and learn on electrical circuits using diligent products? 

    PS. our children range from ages 7 - 17 

     


  2. Okay thanks for that, I think I have a better understanding now. That said, what would be the proper way to position the resistor in my circuit? 
    Would I place the resistor in series on the positive side of the circuit, or across both sides(+ and -)?

    With that being said, and just to be sure I'm understanding, connecting C1 to ground would be the wrong approach to take in this particular case?

     


  3. On 3/20/2017 at 3:16 AM, attila said:

    Just to be sure I'm understanding this correctly, is this approach based on using two channels?
    That is to say, one channel measuring each side of the resistor?
    And then using a math-channel to calculate the difference i.e. the voltage drop across the resistor?


  4. On 2/24/2016 at 0:23 PM, attila said:

     

     

    Hello,

    Thank you for your opinion.

    Currently you can use the custom Math channel to calculate the current value on a given resistor and adjusts the additive test circuit offset error, like:
    M1 = C1 / 0.0471 - 0.0012 (for ~47mOhm resistor and 1.2mA error)

    Hi attila,

    I too would like to know how to do this, and so I wanted to ask if you could provide screenshots on how to do this?

    Sincerely,
    JohnB


  5. Actually I was trying to use the 1 and 2 + /- off the BNC module. which was messing-up my readings. - Lesson learned.
     
    PS. it might be helpful to add a note in the BNC module to highlight the pin-out changes. Not sure if it's indicated in the overview etc. but I missed this, and it cost me alot of time and effort in trying to get things setup properly. 


  6. NC = No Connectivity?

    As it turns out, this was my issue all along. As I was trying to use the leads(ether Waveform Gen(1,2) and the Oscilloscope(P,N) to calibrate with.
    To which I'd add, I did not see the pin-out assignment changes in the BNC documentation :/

    That said, I'm happy to report that the unit is now calibrated and the waves and behavior looks much better than it did before.  
    Too bad it took this long to figure out the problem though. 


  7. Okay so I had another go at it and found the same error;

     

    Check the connections!!
    The measured voltage on Oscilloscope Channel 1 is between: 2.244575 V and 2.245164 V
    But it should be around: 5 V

    It might be that the Arbitrary Waveform Generator 1 Offset is not calibrated correctly.

     

    That said, are the break-out leads on the BNC modules working in the same way as they would be directly from the unit? 


  8. 7 hours ago, attila said:

    Hello,

    The calibration should work with the BNC adapter too, just make sure to have on Scope DC coupling and 1X probe, and 0 Ohm for AWG.

    On Analog Discovery (1&2) the Scope input compensation can be adjusted using the 4 trimmers on the board. Using the wire kit the process looks like this:
    Using square waveform of 2-5kHz, 2V amplitude, select auto synchronization, and in scope have 20-100us/div, 500mV/div range, trigger on Wavegen 1.

    1. Connect the W1 to Scope 1+ and 2+, connect 1- and 2- to ground.
    Adjust 2nd (1+) and 3rd (2+) trimmers to have a good square wave.
    C1 right and C2 overcompensated:

    2. Connect the W1 to 1+, 1-, 2+ and 2-, and reduce ranges.
    Adjust 1st (1-) and 4th (2-) trimmers to have straight line.
    C1 right and C2 overcompensated:

    On the BNC adapter the 1- and 2- are tied to ground. 
    The probe 10X compensation can be adjusted with the probe trimmer based on a 1-2kHz square wave.

    Awesome info yet again!
    I'll give it a try just as soon as I get in today. - Fingers crossed 


  9. Thanks for the response. 

    As it turns out, I discovered that my BNC adapter was the culprit. I removed it and everything came to life (as intended). Though I'm still not sure what is causing the anomalies at the moment. Though the moment I remove the module, everything displays as it should(voltage, waveforms etc). And so I guess this is good news in that I don't have to send in my unit for repair. 


  10. It appears as though my unit cannot be calibrated (error) on voltage. 
    I tried calibrating it several times to try and get it to display wave-forms properly, but the calibration fails on the second portion of the scope as a result of the offset being to far out of spec. 

    Given the rash or issues I've been having with this unit since we received it, I'm beginning to think it's malfunctioning and should be returned for further inspection.
    Needless to say, I can't help but feel as though we've gone in the wrong direction with this purchasing instead of getting a physical scope. :/


  11. Another update, and in an attempt to identify the issue(user or otherwise) I downgraded the software increimentally down to 3.1.5 and found that the Logger does show activity on the Meter side with DC, though the readings appear significantly skewed. 

    That said, and with this in mind, is it possible that my device is not working properly?
    I've had my doubts about the unit since it arrived as it appears to have been erratic in function. Sometimes working, sometimes not without changing settings etc. 

    Which leads me to ask if there's a diagnostic tool I could run on the Discovery 2 itself to test it?


  12. 8 hours ago, attila said:

    Hello,

    For simple AC and DC measurements you can apply to the Logger tool which uses the Scope inputs.

    Just wanted to update to say that I can't seem to get any readings from the Logger tool with Waveform 2015 r3.3.5
    ie, 
    Connecting probe to ch 1, attaching to 5v DC source returns nothing 
    Connecting probe to ch 1 and 2, with 5v source, returns nothing also 

    I tried with different  probes just to be sure. Though the results are the same


     


  13. 6 hours ago, attila said:

    Hello,

    For simple AC and DC measurements you can apply to the Logger tool which uses the Scope inputs.

    Hi attila, and thanks for the response. 

    For the Logger inputs, are we to use one probe(channel) for the input?
    That said, on the measurement side, I'm not seeing simple AC; simple DC, AC RMS and true RMS per channel. Is there a setting or adjustment to view simple AC also?


  14. I noticed the wave shape with our Discovery is slightly deformed(on the edges) and wondered if there was a way to trim or calibrate this with the unit itself?

    I tried with different leads(rated for 150Mhz) and compared to another scope, and found the signal distortion was consistent.at lower frequencies(>1Khz). 

     

    JohnB


  15. Hello I'm happy to report that we've received our Discovery 2 education package and are looking forward to using it in our upcoming labs. 
    That said, I'm a little confused as to how to use the device based on my limited experience with Analog Oscilloscopes. ie, I connected the device (power supply) and USB cable to the PC and the software detects the device and press select. - the loading bar loads, and presents me with a menu. 

    In the next step, I attempt to measure a 5hz signal coming from a LM358 circuit running on 30v. 
    After loading the scope, I attached a probe /lead to the CH1 and attach the probe clip and ground to the output connectors of the circuit but saw nothing. There is no activity line whatsoever. 

    Can anyone help identify why I'm not getting a waveform (reading) with my current setup?

    PS. I Have CH1 selected in the interface and the Discovery 2 device is showing a flashing green LED on it. 

    Thanks for your help with this. 

    Sincerely,
    John