| Products > Test Equipment |
| TH2830 vs TH2832 |
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| KungFuJosh:
--- Quote from: Martin72 on July 22, 2023, 10:03:53 pm ---Yepp, but with a little difference.. ;) --- End quote --- Oh, yeah, I didn't want them in series though. My tests apply to the ST2832 and the ST42. If my board was dependent on series results, then I couldn't test with tweezers. Why do you like the other way better? |
| nctnico:
--- Quote from: Martin72 on July 22, 2023, 09:34:10 pm ---If I may "steal" your idea, I would design it something like DMMCheck had done with the L/C option board.. --- End quote --- With such traces you can end up in tens of nH. That would already add more than 1% of uncertainty to the 1uH inductor on the DMM check board. Not to mention the stubs you get. IOW: IMHO the DMM check style board is very unsuitable for measuring small component values accurately. There is a very good reason LCR meters have these fancy adapters for measuring components. |
| Martin72:
Nico... ;) I wouldn´t start with nH, because like I said before in this value range every mm counts.. The LC-Optionboard: Values were measured out by a frequency of 10kHz, it was "wise" from them not to go higher. |
| KungFuJosh:
You're both missing the point. The actual value of the target isn't that important. What matters most is the value you get from the test device at the testing points. For example, if you send the loaded PCB out for calibration, the cal lab will certify the values they read at each test point. That calibration is your reference, not what values showed up on Mouser's shopping cart. The specific component value doesn't matter at all, as long as it can be calibration verified. Then you check against the calibration values to see if your meter is in spec. Is this inductor 1.0039345mH or 1.003955mH? If that difference matters to you, you need to get it calibrated anyway. For me, if it says 1.00mH, the rest of the digits aren't that interesting. For my needs, all the values were close enough to see where there are and are not issues with my LCR meter. I doubt I'd ever have the PCB calibrated, but I can refer to my saved cal data and see if my meters are still consistent in a year or 10. All that said, the values between the ST42 and the ST2832 were close enough. The ST42 tweezers were used directly on each test device. I suppose, if you actually care enough to get it calibrated, you can have a direct tweezer test and a separate test point test done for reference of both testing methods. I think you're both thinking too much like this is a functional circuit where the component value actually has an effect on something. |
| nctnico:
--- Quote from: KungFuJosh on July 22, 2023, 11:43:45 pm ---You're both missing the point. The actual value of the target isn't that important. What matters most is the value you get from the test device at the testing points. --- End quote --- That doesn't make sense because at the point where the board itself starts to influence the component value significantly (which is definitely the case for the low component values) you won't have a sensible measurement to begin with. Especially with the large antennas attached to the parts that will pickup whatever noise is in the air. If you want to make an LCR calibration standard on a board, then make a 4 layer board that has 4 BNCs that can plug into an LCR meter, use the outer layers as shield and run the signals from the BNCs on the inner layers seperately to pads to solder a part. IOW: the traces connect at the part only. This board can only hold 1 component. But even then you can only test parts that have a significantly higher value compared to the variations between the boards. Adding a shield can over the the component helps to improve the stability of the readings even further. BTW: you will need several of these boards including an open and a shorted one. |
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