| Products > Test Equipment |
| TH2830 vs TH2832 |
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| 2N3055:
--- Quote from: KungFuJosh on July 09, 2023, 06:15:57 pm ---That's all great theory, but we've already shown in practice that the meters we're discussing here can in fact accurately measure 100KΩ at 100kHz and 200kHz. Those charts also point out that what I said is accurate. Using the correct test subjects at the correct test frequency was skipped. They only used a limited range of cap values that can be read in a broader frequency range. Most likely to reduce labor costs, or because whatever standard Tonghui was pretending to do didn't require anything beyond that. This gives a generalized result, without getting into more detailed specifics. Attached here is the chart from the Sourcetronic manual for the 283X models. --- End quote --- There is nothing funny about that chart. As C or L start to approach a limit of zero or infinite ohm at the edges of chart, internal noise of instrument and accuracy of components (drift etc) start to be as large as measured component value.. And accuracy will drop off gradually, as it is shown.. To simplify it, it is about accurate measuring amplitude and phase of low micro(nano)volts and low micro(nano)amps.. Instruments cannot have unlimited dynamic range.. Middle of the chart is a sweet spot, Goldilocks area, hence best accuracy.. To the extremes, it worsens gradually.. |
| KungFuJosh:
Of course. Now let's look at collected data: --- Quote from: luudee ---200 KHz: 100.35 KOhm 100 KHz: 100.33 KOhm 10 KHz: 100.36 KOhm --- End quote --- --- Quote from: KungFuJosh ---The buggy ST2832 firmware failed at a lot more than just high freq. ST2832 100KΩ: 100Hz = 49.5052 1kHz = 67.6866 10kHz = 78.2236 100kHz = 98.1972 200kHz = 91.5881 ST2832 100K DCR = 100.057 ST2832 10kΩ @1kHz fail = 6.78268 Same hardware, 100KΩ, switched back to TH2830 firmware: 100Hz = 100.013 1kHz = 100.013 10kHz = 100.005 100kHz = 99.8795 --- End quote --- Assuming the worse option from the chart above (0.35) at 200kHz, that gives us a +/- range of 99,650Ω to 100,350Ω. luudee's 200kHz reading stated 100.35 kΩ, which is as expected. So theory and practice agree. However, it being higher in all 3 ranges implies the resistor itself is high, and the meter accuracy is better than expected (though still within expected range). The readings are goofy with the buggy firmware. |
| Martin72:
--- Quote from: 2N3055 on July 09, 2023, 05:02:57 pm ---This nomogram is just nicely plotted that... --- End quote --- ...It´s too good to be true.. ;D |
| luudee:
@Josh, the only thing that is buggy/not working/bad accuracy, is when you flash 2832 FW in to 2830 HW. Perhaps the CPLD is slightly different for the units ? When you stick with the original FW, you DO get proper readings, correct ? BTW, the accuracy chart is exactly the same as in the Tonghui User manual. Cheers, luudee |
| KungFuJosh:
--- Quote from: luudee on July 10, 2023, 02:45:54 am --- @Josh, the only thing that is buggy/not working/bad accuracy, is when you flash 2832 FW in to 2830 HW. Perhaps the CPLD is slightly different for the units ? When you stick with the original FW, you DO get proper readings, correct ? BTW, the accuracy chart is exactly the same as in the Tonghui User manual. Cheers, luudee --- End quote --- The ST2830 firmware also has similar issues to the ST2832. Both Sourcetronic firmwares are older than the Tonghui versions. The ST2830 firmware has less bugs compared to the 2832. The hardware is identical between the units and likely the brands too. I'm sure all the user manual stuff is essentially the same besides the logos. Actually, if @Martin72 could get pictures of the inside of his ST2830, that would be awesome...but I don't know if he can, since it's a work meter. I wonder if they have different silkscreens on the Sourcetronic versions or not. It's only 3 screws. 😉 |
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