Author Topic: 500 ppm LCR Meter at Elektor March 2013  (Read 40518 times)

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Online BravoV

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #50 on: March 14, 2013, 01:53:11 am »
My "simple" uSupply USB has over 50 resistors on it!
Some designs just take what they take.

Dave.
C'mon Dave, this is my lame ee wannabe grade standard.  :P

Offline daveatol

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #51 on: March 16, 2013, 04:55:16 am »
It uses 0.01% resistors.
Accuracy is only claimed over +/-2 degC range
And I see a 0.01% 100R (and 1K, 10K, 100K) resistor in series with a 74HCT4052 mux  :-//

Dave.
Hi Dave,

If you have a close look, you'll see that the 4052 (like the probes) uses a Kelvin connection. Therefore the resistance of the MUX is irrelevant.

-David
 

Online kripton2035

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #52 on: March 26, 2013, 10:18:43 pm »
to go back about the original post : the new elektor lcr meter
I was (partialy) wrong : the source of software and firmware will be published it seems
it will be sold fully assembled (I was right about this one...)
for $275 / EUR 200 so that's quite affordable for this precision.

Offline vivaT

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #53 on: April 25, 2013, 08:05:35 pm »
Actually its 254.04 EUR for just the main-board and lcd. Now add an overlay, kelvin clips, housing and time spent and were talking about approaching the full consideration for what this is. So, elektor, bit of a misspick with this design when so many high quality meters can smash that price.

 

Offline fqahmad66

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #54 on: May 03, 2013, 04:42:54 am »
The Project is open source..
 

Offline boneDragon

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #55 on: June 30, 2013, 05:24:38 pm »
Better IC for LCR meter - STM32F303, on STM32F3Discovery (wich costs only about 10..20$).
Contains 4 fast independent ADCs (no I/U switch -> parallel measurement), programmable dif.opamps (no external expensive PGA), 2 DACs.
So only external components are DAC buffer and current shunts selector.
All calculations (I/U multiplication/FFT) can be easily done real-time in firmware (M4 core is fast and contains DSP instructions).
I think a good solution would be to create simple shield for F3Discovery - 10 times cheaper than Elektor.
« Last Edit: June 30, 2013, 05:32:16 pm by boneDragon »
 

Offline Zad

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #56 on: June 30, 2013, 11:23:07 pm »
The best processor for any given project is...

...the one you already know inside out. The hardware, the firmware, the dev environment, the bugs etc. If the designer knows the 8051 then moving to an ARM core would have cost money and time. I wholeheartedly agree though that Elektor should move to open source their software. This can only benefit the product in the long term, as people debug it, add extra functions, improve accuracy (I'm preaching to the choir here).

I would have used an AD5933 anyway (demo board $59 from ADI) which has its own flexible DDS frequency source, current-to-voltage conversion, 12-bit ADC and even an internal temperature sensor. I say 'would have', I did. As ever though, without the motivation of commercial product deadlines, it died a fuzzy death somewhere after I laid out the first PCB.

Offline Vgkid

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If you own any North Hills Electronics gear, message me. L&N Fan
 

Offline quantumvolt

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #58 on: July 01, 2013, 08:24:08 pm »
If it is truly open and quality hardware can be bought, some people (including me) might find it worthwhile as a long time 'research' project. The principle is called "Auto Balancing Bridge" and is the principle primarily chosen by Agilent for low-mid frequencies. Search will give many readable links. A good starting point is "Agilent Impedance Measurements Handbook" http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf.





Source http://mrl.upesh.edu.pk/facilities/lcr_meter.html (good read ...)
 

Offline kodi

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #59 on: October 10, 2013, 05:01:44 pm »
If it's not measuring at 100kHz, then it's still too expensive for me. Actually If I already didn't have two RLC/ESR meters I would try this one: http://radiokot.ru/konkurs/53/ . Simple, cheap, four wire. And uses LCD that costs beween $1 and $2. And fits in your pocket.
 

Offline fqahmad66

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #60 on: November 25, 2013, 07:09:59 am »
finished mine...measures as per specs.
 

Offline kodi

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #61 on: November 26, 2013, 11:39:13 am »
Would you mind sharing the building and calibration experience? Does your build incorporates latest hardware changes (published in November edition of Elektor)?
There was a lot of discussion and bug squashing regarding this device (including comment from the author that there was printing error about specs at low end of inductor measurement).
 

Online BravoV

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #62 on: November 26, 2013, 11:51:25 am »
How much in total you have spent in building this ?

Offline fqahmad66

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #63 on: November 29, 2013, 09:51:58 am »
Hi,

First this is a Hobby project and is meant for fun of building & learning.
Made my own pcb. fab from seedstudio..now have 4 spares.

- using software version 3.0.
- no harware mode.

for initial testing made some crude probes..see picture. Sheild should be close to test point. Open and short circuit trims worked fine. Measured a 0.012 ohm 1% resistor (salvaged from sony laptop battery). With carefull zero trim it measures 0.012.
RF coils are specified at MHz frequencies...this meter is not for measuring RF coils..max test frequency is 10KHz. I measured one Toko 7mm coil with 0.27uH at 50MHz. The meter measured 0.22uH which is probably OK.

All my inventory 1% resistors and caps measured within tollerances.

Regarding cost..BOM is available at Elektor site..most of the parts are available from Mouser or Digikey...around 300USD

Minimum L range is 100nH.


« Last Edit: November 29, 2013, 10:08:52 am by fqahmad66 »
 

Offline kodi

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #64 on: November 30, 2013, 08:00:20 pm »
I know those probes... any chance you are going under the name " hadihf " on Elektor forums?

$300 for parts for main board only? Yeah I was doing budget calculation and got down to $350 for the whole thing with display board as well, but got some parts in my drawers... Now 300$ for built (but not calibrated) boards from Elektor looks almost like a bargain :)

Congratulations you had enough will to build this project from start to finish!

PS. And no, it will not work properly in 100nH range  - it was supposed to be 100mH, but there was a printing error.
 

Offline fqahmad66

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #65 on: December 01, 2013, 04:59:40 am »
Thanks. I meant lowest reliable measure = 100 nano Henry (nH) = 0.1 micro Henry (┬ÁH). I had a couple of 0.18uH 0805 ones amd meter is measuring .18~.19.
 

Online BravoV

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #66 on: December 01, 2013, 11:06:09 am »
Looking at the $300 figure, personally I lost my appetite, with Cyrustek based LCR meters out there that is priced < $150 with capabilities 100KHz test signal, 1 mOhm (mili Ohm), 1nH (nano Henry) and 10 fF (femto Farad) resolution + 2 sets of 4 wires measuring clips, and "fully calibrated" from factory, this Elektor lcr meter looks way too expensive, again, imo.

Of course unless you aim for the fun on the process of building and calibrating it, but thats another story I guess.  :-//

Offline mos6502

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #67 on: December 01, 2013, 07:42:38 pm »
Agreed. That price is a joke. You can buy a DE 5000 for 1/3rd the price. And that comes fully assembled, can do 100kHz, actually has buttons and a display ...

The whole point of a kit is to get the thing cheaper, not more expensive.
for(;;);
 

Offline Rufus

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #68 on: December 01, 2013, 07:57:39 pm »
The whole point of a kit is to get the thing cheaper, not more expensive.

For something mass produced in China kits will hardly ever be cheaper.
 

Offline kodi

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #69 on: December 03, 2013, 09:21:57 am »
Agreed. That price is a joke. You can buy a DE 5000 for 1/3rd the price. And that comes fully assembled, can do 100kHz, actually has buttons and a display ...

The whole point of a kit is to get the thing cheaper, not more expensive.

Actually if you look at specs, the Elektor kit should be much more accurate than DE 5000, so the price wise argument is moot. The kit has possibility to work as standalone unit (it has a daughter-board with "buttons and display"). You have to learn how this thing work to build it properly and calibrate it - and that was the whole idea.

There were minuses to this whole project - basically it was published before it fully matured, so to this day I know about 3 (three)  working devices that were built from scratch and calibrated. People were scared to build it. The parts for the kit are expensive, especially when you are purchasing them in quantities for single unit. Even with samples program it's hard to get below $250, so some people decided to go simpler route with ordering, for few percent more, the assembled boards. Which weren't working properly, because of some software issues. People got frustrated, because it wasn't working out of the box as advertised ("Luxury of precision within everyone's reach") additionally boards they purchased should be modified a little and the project in the end wasn't that spectacular marketing success.

But. If you want to learn how that kind of stuff work and understand how to make proper measurements - it's a great tool.

 

Offline ElektroQuark

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #70 on: December 03, 2013, 09:51:21 am »
Is the correct PCB available?

Online kripton2035

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #71 on: December 03, 2013, 10:32:12 am »
sorry but the first elektor lcr meter was soooo innovative compared to this 2013 one that the 2013 lcr meter is simply not interesting ...
the de 5000 is a good alternative for someone that wants to measure
and to discover the wonderful world of the inside of lcr meters the russian DIY "go" lcr meter is made of very simple and available components for an accuracy that is very nice. IMHO.

Offline fqahmad66

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #72 on: December 03, 2013, 11:13:20 am »
Is the correct PCB available?

Probably not...EC will not be scrapping already stocked 100+ pcbs...you will either have to make your own yor use a knife..

I would like to mention here that there is difference between PCBs available at EC and mine. The ref pin of INA128 is connected to AGND at a common point to R46 AGND.
« Last Edit: December 03, 2013, 11:46:09 am by fqahmad66 »
 

Online BravoV

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #73 on: December 03, 2013, 11:35:58 am »
But. If you want to learn how that kind of stuff work and understand how to make proper measurements - it's a great tool.

I strongly believe there are alternatives or even better choices out there that are much more cheaper, "IF" the purpose is just to learn.

Btw, just curious, how to calibrate it until it has "good enough" accuracy as its designed ?

And the most important aspect, is the calibration process realistic, if its done at an "enthusiast/hobbyist" grade lab ? Worry that it needs those precision references or supporting specialty instruments which I believe most of the cases are unreachable by 99% of the hobbyist/enthusiasts crowd out there.
« Last Edit: December 03, 2013, 11:38:23 am by BravoV »
 

Offline Rubi

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Re: 500 ppm LCR Meter at Elektor March 2013
« Reply #74 on: March 24, 2015, 08:15:05 am »
Hi

I just finished mine, I bought the pcb from elektor and sampeld the more expansive components, so I got away pretty cheap.
Unfortunately I am still searching for a matching lcd.

The build process was fun, except the silk screen on the Elektor pcbs is horrible, so I often had to compare against the schema.

The next step is to modifiy it a suggested from Elektor to get better accuracy.
Even without mod I tested it in the university lab against an Agilent U1773C an Hameg HM8118 and a Philips PM6303 .
I was impressed by this meter. When I am finished with the mod I will note the results and post them.

Usually Elektor circuits are expensive and half baken, this one looks like a positive exception.

Cheers
Michael
 


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