Products > Test Equipment
XJW01 Auto LCR meter review ($120 bench top LCR meter)
nctnico:
When looking for an LCR meter on Ebay I came across a cheap LCR meter for less than $120 including delivery. I couldn't help myself and bought it...
Specs
R 0.0002 Ohm — 9.999 MOhm
C 0.1 pF — 10000uF or more
L 0.01 microH — 1000 H
D,Q 0.001 — 9999
For capacitors and inductors it also shows Q, D (dissipation factor?), ESR and DC resistance. It can be switched between three test frequencies: 100Hz, 1kHz and 7.8kHz. It comes with cables to make a 4-wire connection to the 'component under test'. The mains cable looks like it is for Australia.
First impression
After the unpacking the box (which came from Belgium???) I found a sloppy casing which wasn't even closed. The inside was filled with plastic wrappings from apples and pears. At the back it says 110V. A kit with screws and feet to close the casing is also included. A manual is missing though. A quick look at the inside reveals one of the leads of the transformer is damaged and the person who assembled the unit used lots of hotmelt glue. For a prototype it would be OK but not for a production unit. The casing is too floppy to close nicely.
Does it work?
One wonders... Over here we have 230V so I used a variac to get 110V. It started but the readings where not very stable and every time I pressed a button it crashes. One thing I noted was that the beeper sounded for longer or shorter periods before the crash. Maybe it loaded the power supply too much so I removed the beeper. This made things slightly better but still not perfect. After some measurements on the inside it appeared the power supply voltage was too low. Next to the connector to the transformer the silkscreen says 9V (AC). I only measured 6V (AC). So I cranked the variac up to 130V. This made the display brighter, stopped the device from crashing when pressing a button and caused the readings to become stable.
I measured some inductors, capacitors and a few resistors. The values shown seem right. My Agilent DMM says the resistor is 5956 Ohm where the LCR meter measured 5954 Ohm. Because there is no manual it takes some time to figure out what the buttons do. There are 3 buttons called C, R and L but those don't switch between the measurement modes :palm: . The X button switches between the measurement modes (the default is AUTO in which it detects what kind of component is connected). The R and L buttons switches between display modes (to show imaginary resistance for example). The C button enters a self calibration mode. The Q button switches between an angle and a percentage (of what?). Furthermore the display shows the range and test frequency. The F button changes the test frequence and there is an M button which enters some kind of frequency adjusment menu.
Overall
When I saw it was 110V I ordered a small transformer and I'm definitely going to put it in. For the money the unit does what it should do. One interesting aspect is that most of the components are through-hole. I even spotted some CD4052 devices inside. On the other hand there are several SMD diodes on the component side and solder side. That seems a bit weird to me because it makes production more difficult then necessary.
Photos:
Carrington:
Interesting!
But no more specification? Basic accuracy, for example.
Edit:
Ok, 0.3%.
http://easy-taobao.com/taobao/view/id/18077625596
http://easy-taobao.com/taobao/view/id/22601240432
Within a "economic" range, I like these two: AT825 and U822C.
nctnico:
One of the reasons I bought it was for the 4-wire connections so it can measure low resistance values accurately. I think I also want to modify it to be able to apply a DC bias.
quantumvolt:
Any more experiences with this meter? I will buy one soon. Strange there is not more interest in it here - it is a real half bridge with phase detection (the Greek 'Theta' in the display):
Not at all like all those PCBw/328+1602 and handheld devices from eBay. It uses the same I/V or Autobalancing Bridge principle as Agilent and the other bench top LCR meters ...
The first post in http://www.crystalradio.cn/thread-231933-1-1.html - started by the 'constructor' "xjw01" - has a .rar-file with documentation, schematic and code. The thread - started in 2011 - is still alive in April 2014 - with thousands of posts on some 370 pages.
Nice project to study. I might even learn some Chinese ...
Vgkid:
I'm curious why they chose the 7.8khz frequency, It is not to far off from the usual 10K frequency.
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