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New 2ch pocket DSO+SG - Zeeweii DSO2512G
Dry:
Found a solution for the DC measurement balance issue. There is a possibility of manual calibration DC offset and gain by opening Meas in Menu, then shortly pressing CH1CH2 button (the green 2 appears) and then hold V to enter the offset calibration mode or hold mV to enter gain calibration mode. The calibration is made by pressing vertical arrows for the channel 1 (in both modes) and horizontal arrows for channel 2. NB: offset calibration is set for each vertical scale value separately, but the gain value is one for all diapasons on each channel. So to make the calibration rapidly and correctly you need to start with offset for each diapason (the appropriate vertical scale should be chosen before entering the calibration mode, it cannot be changed when calibrating), then chose the vertical scale value where the DC values are median and use it to set the gain. I managed to set the DC measurement accuracy pretty within 1% (see photos, CH2, the true value is 8,25 V). Before the max spread (at 20 V / div) was up to 15%!
REWEREWE:
--- Quote from: Dry on December 14, 2023, 11:59:43 pm ---... I managed to set the DC measurement accuracy pretty within 1% (see photos, CH2, the true value is 8,25 V). Before the max spread (at 20 V / div) was up to 15%!
--- End quote ---
Thanks for the detailed description of calibration. I would like to draw your attention to the fact that if we calibrate different vertical ranges of the scale using the same voltage, we will get a fairly large error for voltages typical for each scale.
Dry:
--- Quote from: REWEREWE on December 17, 2023, 11:09:48 am ---
--- Quote from: Dry on December 14, 2023, 11:59:43 pm ---... I managed to set the DC measurement accuracy pretty within 1% (see photos, CH2, the true value is 8,25 V). Before the max spread (at 20 V / div) was up to 15%!
--- End quote ---
Thanks for the detailed description of calibration. I would like to draw your attention to the fact that if we calibrate different vertical ranges of the scale using the same voltage, we will get a fairly large error for voltages typical for each scale.
--- End quote ---
May be not, because the gain is the same for the whole set of scale ranges, you can adjust on each range only the 0 (DC offset). In fact I used the same voltage to calibrate my device (and combined probes gain x1-x10 and device sensitivity x1-x10), but after that I have no sign. error with real voltages.
PS: The DC measurements are much more accurate in two channel mode, I have no idea why.
chemary:
I have noticed that some measurements change when switching from normal mode to single mode, is like if it adds an offset. It's happening for certain signals on AC and DC mode. If I keep switching from normal to single at some point it gets fixed. I have restarted multiple times and keeps happening. To reproduce I only have to power-up the unit, click auto and then single. Maybe somebody can explain what is happening looking at the screenshots.
The hardware version is V9.15 and the firmware v1.3.0C
[Update] while testing to write this post, with the same signal (well is a joule thief output and has slightly changed) I can no longer reproduce the problem, but I used an other signal (joule thief input "attachment sample3.jpg") and it happens again, I also checked with a better oscilloscope and the normal mode values are correct.
[Update2] It happens even with the integrated FG, to reproduce I set 1Khz sinusoidal, I click "auto" then I decrease vertical scale with "V" and press "single" and that's it I get incorrect measurements.
Dry:
I tried to reproduce the issue when measuring in AUTO and in SINGLE mode, and got the same strange results - regardless of number of waves on the screen and trigger position. But since I changed the waveform (in built-in generator), the measurements became correct, and stay correct after on-off procedure and with all waveforms. But! I noticed that the incorrect values are displayed when I move the waveform up and down (only in SINGLE mode indeed), however when switching between AUTO and SINGLE no more issue is observing.
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