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Perfectly working 500ppm LCR meter?

Equipment, circuits, projects, procedures

Postby hadihf » Mon Aug 19, 2013 12:00 am

Hi everybody,

Since it is a considerable investment..i wonder how many of subject meter owners are having it working within specs? I agree there is no alternate to fun of building such a project even if initially it does not work perfectly.

Regards
F
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Postby ricks » Wed Aug 28, 2013 12:00 am

I built one by hand and I'd recommend it. It was a fun couple of days. solder,drill,file,test. As far as spec go, I lost my job where we had a Philips LCR meter, so have nothing to compare against other than R with the HP 3478A. I had a precision 100 ohm WW 1/10% R and it measured within spec. I have no 1% caps, on hand, but 2% seemed okay. Tried some big ecap 20mF, seemed to measure these okay.
I know the fellow said he had issues with low L, and he said he made a good fixture. I tried some leaded 100nH, it was way off but I have only those kelvin clips. A fixture is something that you really need. Just downloaded V3.0 so will give it a go and see how the trim problem fix goes.
I see that there is a mod as well, hopefully just a value change, no barnacles.
From the sounds of it, have to wait for the Nov edition for the mod info, oh boy, and I have a digital/green version
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Postby snoopy_94 » Wed Aug 28, 2013 12:00 am

Some measurements on a LCR-meter.
The mod will be on the October issue.

Jean-Jacques
Attachments
LCR-Meter.pdf
(42.06 KiB) Downloaded 128 times
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Postby hadihf » Wed Aug 28, 2013 12:00 am

Here are the mods from LCR3A.h...

// 3.0.0 Improved input offset, *** only if a resistor found on pin 9 of J16 ***
//Harware modifications on "AU2011 - Main Board Rev3" PCB:
//- R34 removed.
//- R46 becomes 10R.
//- Isolate pin 5 of U5 (INA128), and connect it to the R45, R46, R47 common point.
//- Put a 10 k resistor (size 0805 or 0603) between pins 9 and 11 of J16 (on the bottom side).
//
//New Menus for adjustement of "Lim_Dac8811_Index_V", used on Range 1 for DAC8811_Index_V, and
//"Lim_Dac8811_Index_I", used on Range 8 for DAC8811_Index_I; works also with non-modified unit.
//
//New message "BAD_OFFSET" added


Regards
F
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Postby ricks » Wed Aug 28, 2013 12:00 am

From the Elektor Editor: contrary to what Jean-Jaqcues states, the description of the LCR Meter hardware modifications will appear in the November 2013 edition of Elektor. The English-language October 2013 editions of Elektor are being finalized for printing at this time.

Jan

I loaded V3.0 and it fixes the short ckt trim issue I had in the previous version.
Thanks for the update
Rick
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Postby thijsbeckers » Wed Aug 28, 2013 12:00 am

Snoopy_94Some measurements on a LCR-meter.
The mod will be on the October issue.

Jean-Jacques


More accurately, they will be in the French October edition... We didn't get the translation done before deadline, so in the English (and German and Dutch) edition(s) it'll be in the November edition...
We apologize for that.
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Postby snoopy_94 » Thu Aug 29, 2013 12:00 am

hadihfHere are the mods from LCR3A.h...

// 3.0.0 Improved input offset, *** only if a resistor found on pin 9 of J16 ***
//Harware modifications on "AU2011 - Main Board Rev3" PCB:
//- R34 removed.
//- R46 becomes 10R.
//- Isolate pin 5 of U5 (INA128), and connect it to the R45, R46, R47 common point.
//- Put a 10 k resistor (size 0805 or 0603) between pins 9 and 11 of J16 (on the bottom side).
//
//New Menus for adjustement of "Lim_Dac8811_Index_V", used on Range 1 for DAC8811_Index_V, and
//"Lim_Dac8811_Index_I", used on Range 8 for DAC8811_Index_I; works also with non-modified unit.
//
//New message "BAD_OFFSET" added


Regards
F

Pending the publication of the material change, I recommend strongly to update the firmware to version 3.0.0 and use the AU2011 program in version 3.0.0.
In the program AU2011, "Preferences" menu, after checking "access to adjust. menus", it is possible to adjust the maximum value of the levels of the final amplification (value 5 by default on a non modified LCR-Meter).
For the 8 range which enables to solve the problem of TRIM OPEN-CIRCUIT, and for the 1 range to measure low resistances (and solve the TRIM SHORT-CIRCUIT problem).
The hardware modification allows to work with the full amplification in range 1.

Jean-Jacques
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Postby ricks » Fri Aug 30, 2013 12:00 am

Hi Jean-Jacques & others.
Took a look at the mod, interested to read the INA128 DS to get more info of what you did. Nice use of the DAC & the INA128 a ref pin.
Oop's maybe I should wait til November to read officially how to do the mod, na, I will do it shortly and hopefully be done with mod's.
Wonderful project, one of Elektor's best!! It is a real product, not some toy. Keep them coming.
Cheers
Rick
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