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XJW01 Auto LCR meter review ($120 bench top LCR meter)
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dannyf:

--- Quote ---Nice project to study.
--- End quote ---

Nice project. A very innovative design.

- Cx@K3 produces the voltage across the DUT; Cy@K3 produces the current through the DUT.
- sine wave produced through pwm;
- the most interesting part is OP07 and V1/V2 as a phase detector: I have used similar designs in the ESR meter. It is a digitally controlled phase detector without resorting to analog switches - the typical implementation.
- I didn't look at the software but he must be doing some fairly sophisticated math there.
- He used a 8051. With a faster chip, he can simplify the design considerably and go much higher in frequency.
- the calibration procedure is a little bit too complicated. But the fact that it is implemented at all is a huge plus.

nctnico:
I'm starting to like this little critter more and more. The good old HP4274A I bought a couple of months ago could not match it's capability to measure low resistance (tens of milli-ohms). Too bad it only supports a few frequencies.
quantumvolt:
Remote 'comparison' of XJW01 with Hameg HM8118 (new, in calibration - https://www.rohde-schwarz.com/us/product/hm8118-productstartpage_63493-44101.html).

   ... --- ...

Since I saw the XJW01 meter on eBay, I knew I would buy one (https://www.eevblog.com/forum/testgear/xjw01-auto-lcr-meter-review-%28$120-bench-top-lcr-meter%29/msg429607/#msg429607).

In general I like it a bit untidy, sloppy, dodgy ..., and I thought that if it is all junk I can always follow the safety seeking herd and buy a DE-5000 (I will buy that one too  :-+).

I have now had it about a year or so. I have had a lot of fun. To make a long story short I have collected quite a few quality caps (+- 0.5% and a few better). I have built oscillators and Wien bridges using Vishay precision resistors and 2x Agilent 34970A (AC range, interchanged bridge legs with relays) and a precision frequency counter. And a lot of math and statistical estimation / regression. All to determine the 'real' value of capacitors - and hence the errors of my XJW01.

When I thought I knew the errors (for 'all' ranges, values and temperatures) of this box, I put in this ad https://www.eevblog.com/forum/buysellwanted/%28wtb%29-measurement-of-capacitors-%28from-calibrated-lcr-meter%29-%28paypal%29/.

I got an answer from a very nice member here that has a Hameg (Rohde&Schwarz) precision LCR bridge at work. So I sent him the test caps to England and got the results back in email. Thanks a lot for his kindness.

This comparison (3 weeks between measurements) of my XJW01 is anecdotal in the sense that it cannot in any way be generalized, but on a collection of high quality caps (180 pF to 33.3 nF - almost zero loss and almost zero temperature coefficient), my USD 99 (Best Offer) XJW01 meter was never more than 0.155 % off compared to the USD 1500+ Hameg lab instrument.

  :-DMM

Carrington:
Does anyone know where one can buy this other?
And how much it cost?



Source: http://www.crystalradio.cn/thread-373788-259-1.html

Thanks.
happydad:
Can someone explain how the design calculates ESR?  I assume that the actual V & I measurements give us impedance, which is not ESR.  What am I missing?
Thanks.
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