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Products => Test Equipment => Topic started by: BravoV on March 11, 2013, 01:36:20 am

Title: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 01:36:20 am
(http://www.elektor.com/Uploads/2013/2/110758-51.jpg)

Quick specifications*
L range: 0.1 nH - 100 H
C range: 0.1 pF - 100 mF
R range: 0.1 mOhm - 1 Gohm
Q or D range: 0 - 10,000
Phase ange range: -90 to +90 degrees
Rs, Xs range: 0.1 mOhm - 1 Gohm

(http://www.elektor.com/Uploads/2013/2/US201303001.jpg)

I'm not a subscriber, its just I'm curious only at other details on the spec like test frequency, accuracy and etc, thats all.

Appreciate if any of you that is subscribing this could share just a sneak peek or summary on this device's capability please, tia.

Linky -> HERE (http://www.elektor.com/magazines/2013/march/500-ppm-lcr-meter-(1).2415654.lynkx)
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: psycho0815 on March 11, 2013, 07:23:23 am
Here are some more specs:

it measures on 100/120Hz, 1kHz, 10KHz. the 100/120 depends on whether your mains is 50 or 60 Hz.
the Voltage it's measuring at is 0.4Vrms +/- 5%, so it should be ok for in-circuit stuff.

Accuracy is:
0.05% to 0.3% +/- 1 digit each depending on selected Range.
It also does 4-Wire Measurement.

That seems to be all the important stuff.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rerouter on March 11, 2013, 07:29:05 am
and the golden question, how much are they selling the kits / products for... if its under $200, then I'd probably be inclined to straight up order one....
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: firewalker on March 11, 2013, 08:24:59 am
It uses an C8051F061 mcu. I didn't read top to bottom the article yet though.

(http://i.imgur.com/YeTYcLn.png)

(http://i.imgur.com/41GCTEB.png)

Alexander.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 10:02:33 am
I read it, dont like it as it will be a closed firmware... and no real breakthrought in this meter.
I really prefer the GO rlc 2 meter totally open source and quite simplier components.
my 2 cts.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 10:07:12 am
Thanks for replies folks !  :-+

@kripton2035

Damn, I thought it was open soft & hardware, cause from the 1st glance I saw it is somehow using off the shelf components. Really, I was intrigued when seeing those 4 big bnc connectors for the 4 wires measurement, looks really serious stuff.

As Rerouter  mentioned, if the price is right, maybe its still worth considering, but if its way too high, those Cyrustek chip based LCR meters definitely are hard to beat.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 10:24:59 am
it is a 4-5 parts article, will continue till mid 2013 at best
we only have a glance at it I also was waiting for it to compare with all I already know ...;)
but I'm disapointed about it, it will come as a closed firwmare kit as elektor knows to do it for years.
but yes if it is an affordable price for the kit it can be a good deal
as I already said, I prefer the GO rlc2 meter totaly open source, and quite as precise ?
I'm building it right now, I made pcb boards for it and I'm soldering it right now ... nice puzzle all smd 0805 !
will keep you up to date with the progression.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 10:35:12 am
Huh ? Until mid 2013  ? :palm:

Btw, offtopic about GO rlc2, did you purchase it in kit or you're building it from scratch ?

Must be interesting to watch the owner of the most complete ESR circuits repository on earth  ;D building his own LCR meter, can't wait to see the result of your rlc2 !  :-+
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 11, 2013, 10:37:51 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 10:41:58 am
And I see a 0.01% 100R (and 1K, 10K, 100K) resistor in series with a 74HCT4052 mux  :-//
Pardon for being an enthusiast level, are you saying by using that mux defies the purpose of using those expensive resistors ? Again, CMIIW.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: firewalker on March 11, 2013, 11:14:02 am
I can;t remember any full open source project by Elektor.

Alexander.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 11, 2013, 11:16:59 am
And I see a 0.01% 100R (and 1K, 10K, 100K) resistor in series with a 74HCT4052 mux  :-//
Pardon for being an enthusiast level, are you saying by using that mux defies the purpose of using those expensive resistors ? Again, CMIIW.

Those chips are in the order of 50-100ohm on-resistance depending upon voltage, and it varies a lot with temp too IIRC.

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 11:17:35 am
I can;t remember any full open source project by Elektor.
Alexander.
:) projects that does not have any mcu inside ... there are still some !
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 11, 2013, 11:17:55 am
I can't remember any full open source project by Elektor.

That's probably one of the reasons why they turned down my uWatch project  :-//

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 11:19:57 am
And I see a 0.01% 100R (and 1K, 10K, 100K) resistor in series with a 74HCT4052 mux  :-//
Pardon for being an enthusiast level, are you saying by using that mux defies the purpose of using those expensive resistors ? Again, CMIIW.

Those chips are in the order of 50-100ohm on-resistance depending upon voltage, and it varies a lot with temp too IIRC.

Dave.
+1
in the go rlc2 there are "only" 1% resistors in series with the 4052
and as I understood it the software calculates the error
so yes why did elektor use 0.01% resistors in such a configuration ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 11:22:01 am
Btw, offtopic about GO rlc2, did you purchase it in kit or you're building it from scratch ?

Must be interesting to watch the owner of the most complete ESR circuits repository on earth  ;D building his own LCR meter, can't wait to see the result of your rlc2 !  :-+
I build from scratch, there is no kit available that I know of.
and my lcr repository is not bad at all too !
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 11:26:08 am
@kripton2035

Damn, I thought it was open soft & hardware, cause from the 1st glance I saw it is somehow using off the shelf components. Really, I was intrigued when seeing those 4 big bnc connectors for the 4 wires measurement, looks really serious stuff.

As Rerouter  mentioned, if the price is right, maybe its still worth considering, but if its way too high, those Cyrustek chip based LCR meters definitely are hard to beat.
another thought : elektor can also sell this as a complete build board
they often do so when there are a lot of smd components ... and this one is a really good candidate !
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: firewalker on March 11, 2013, 11:27:23 am
I can;t remember any full open source project by Elektor.
Alexander.
:) projects that does not have any mcu inside ... there are still some !

Just "open" hardware. Although I am not sure they give away cad, gerber etc files.

I stopped buying Elektor years ago when bought a kit and located a bug on the firmware. They refused to address the issue or give me access to the source code to fix it my self.

Alexander.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: notsob on March 11, 2013, 11:27:36 am
So as I read this, the elektor unit has closed code for the kit, I wouldn't bother and also 4 x $US7.90 for the article series plus prob $200 for the kit, so if you want to build, go with kripton, or save your $230 and put it towards something better.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 11, 2013, 11:35:36 am
So as I read this, the elektor unit has closed code for the kit, I wouldn't bother and also 4 x $US7.90 for the article series

I paid 10 "elektor credits" for the article, whatever that's worth (I have a bunch from when I got something published).

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: firewalker on March 11, 2013, 11:49:48 am
Huh ? Until mid 2013  ? :palm:

Btw, offtopic about GO rlc2, did you purchase it in kit or you're building it from scratch ?

Must be interesting to watch the owner of the most complete ESR circuits repository on earth  ;D building his own LCR meter, can't wait to see the result of your rlc2 !  :-+

Any link for the GO rlc?

Alexander.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 11:51:30 am
Any link for the GO rlc?
Alexander.
you asked for it ;) : http://kripton2035.free.fr/LCR%20meters/lcr-go-russian.html (http://kripton2035.free.fr/LCR%20meters/lcr-go-russian.html)
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: firewalker on March 11, 2013, 11:53:49 am
Thanks.

Alexander.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Marco on March 11, 2013, 12:36:13 pm
I can;t remember any full open source project by Elektor.

Huh ...  and there goes the chance of me ever subscribing. How are you supposed to learn anything if they don't thoroughly explain the firmware? It's over half the effort of the design.

PS. why the hell would you use a 8051 and use mains frequency of your reference in this day and age? Unless you need ultra-low power you can't beat 32 bit chips for convenience and cost isn't an issue any more and you can't run off batteries if you use mains as your clock source.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Nermash on March 11, 2013, 02:05:14 pm
It does not use mains frequency as reference, it generates its own square signal and filters it to sine...
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Noize on March 11, 2013, 02:14:14 pm
I bought 10 credits this morning for £1 to get the article for that esr meter.


So as I read this, the elektor unit has closed code for the kit, I wouldn't bother and also 4 x $US7.90 for the article series

I paid 10 "elektor credits" for the article, whatever that's worth (I have a bunch from when I got something published).

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: DmitryL on March 11, 2013, 02:26:27 pm
+1
in the go rlc2 there are "only" 1% resistors in series with the 4052
and as I understood it the software calculates the error
so yes why did elektor use 0.01% resistors in such a configuration ?

The more precise resistors in the differentional amplifiers, the better. I used 0.1% in my RLC2, and it didn't hurt :)
BTW, when you finnish the device, don't froget to make Open, Short and Load calibration with a set of known precise  _smd_ resistors, otherwise measurements won't be good enough.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 03:00:07 pm
Thanks to all for the insights of this circuit, glad I didn't buy the credit just to download this issue.

Looking at the test frequency, wonder why they dont make up to 100 KHz as well since this is started from the scratch.  :-//



and my lcr repository is not bad at all too !
My apology, I meant the world most complete diy lcr cicrcuits repository on earth.   :-+
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 11, 2013, 03:03:33 pm
Those chips are in the order of 50-100ohm on-resistance depending upon voltage, and it varies a lot with temp too IIRC.

The channel resistance of the 4052 has no effect on measurements - the design isn't that dumb.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 11, 2013, 03:08:04 pm
It does not use mains frequency as reference, it generates its own square signal and filters it to sine...

It is likely specified measuring at twice the local mains frequency to help reject mains pick up on the component and cables.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: tinhead on March 11, 2013, 03:20:01 pm
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.

they could use at least matched/selected MAX4052A, but yeah, Elektor.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 11, 2013, 04:00:22 pm
in the go rlc2 there are "only" 1% resistors in series with the 4052
and as I understood it the software calculates the error
so yes why did elektor use 0.01% resistors in such a configuration ?

You can't magic absolute accuracy out of no where. Those resistors are *the* reference in the instrument if they are not precise you would have to calibrate them by measuring external reference parts. You would probably want to use precision parts for them to get better thermal and age stability anyway.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 11, 2013, 04:38:57 pm
in the go rlc2 there are "only" 1% resistors in series with the 4052
and as I understood it the software calculates the error
so yes why did elektor use 0.01% resistors in such a configuration ?

You can't magic absolute accuracy out of no where. Those resistors are *the* reference in the instrument if they are not precise you would have to calibrate them by measuring external reference parts. You would probably want to use precision parts for them to get better thermal and age stability anyway.
the point here is that these very precise resistors are in serie with a 74hct4052 that is certainly not 0.01% precise, nor ppm/deg that precise too
so yes you need very precise resistors to make a very precise lcr meter, but why ruin the precision just after putting these resistors ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 11, 2013, 04:51:44 pm
in the go rlc2 there are "only" 1% resistors in series with the 4052
and as I understood it the software calculates the error
so yes why did elektor use 0.01% resistors in such a configuration ?

You can't magic absolute accuracy out of no where. Those resistors are *the* reference in the instrument if they are not precise you would have to calibrate them by measuring external reference parts. You would probably want to use precision parts for them to get better thermal and age stability anyway.
the point here is that these very precise resistors are in serie with a 74hct4052 that is certainly not 0.01% precise, nor ppm/deg that precise too
so yes you need very precise resistors to make a very precise lcr meter, but why ruin the precision just after putting these resistors ?

That part of the circuit is similar in the Elektor and your RLC-2 meter. The resistance of the 4052 has no effect on measurements and is irrelevant in both.

The whole circuit is similar except the RLC-2 uses a quadrature detector to measure phase and the Elektor seems to do it in software.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: enz on March 11, 2013, 04:59:08 pm
That part of the circuit is similar in the Elektor and your RLC-2 meter. The resistance of the 4052 has no effect on measurements and is irrelevant in both.

Correct, the On-Resistance of the 74HCT4052 is only in series with the input of the buffering OP-Amps. The measurement over the selected range-switch-resistor is done differentially.
It's all written in the article and clearly to see in the schematic.

Martin
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Amarbir[Lynx-India] on March 11, 2013, 05:54:12 pm
I can't remember any full open source project by Elektor.

That's probably one of the reasons why they turned down my uWatch project  :-//

Dave.

Dave  ,
 When You have silicon chip in your own country why do you need elektor ? .Other magazines beg borrow and steal articles from SC .A Person having a goldmine never understands the importance then a person who does not .I fancy that semtester they had few months back and now epe mag uk has it hee hee  .That was one awesome project .If you come to india stay with me  ;D
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: nctnico on March 11, 2013, 06:53:32 pm
And I see a 0.01% 100R (and 1K, 10K, 100K) resistor in series with a 74HCT4052 mux  :-//
Pardon for being an enthusiast level, are you saying by using that mux defies the purpose of using those expensive resistors ? Again, CMIIW.

Those chips are in the order of 50-100ohm on-resistance depending upon voltage, and it varies a lot with temp too IIRC.

Dave.
Well, it wouldn't be the first time Elektor published a circuit which doesn't work at all.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 07:29:21 pm
The channel resistance of the 4052 has no effect on measurements - the design isn't that dumb.
Scratched my head quite hard thinking what you said here, made some rough sketch, something looks or similar like this Rufus ? CMIIW

(https://www.eevblog.com/forum/testgear/500-ppm-lcr-meter-at-elektor-march-2013/?action=dlattach;attach=41082;image)
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: enz on March 11, 2013, 08:19:47 pm
The channel resistance of the 4052 has no effect on measurements - the design isn't that dumb.
Scratched my head quite hard thinking what you said here, made some rough sketch, something looks or similar like this Rufus ? CMIIW

(https://www.eevblog.com/forum/testgear/500-ppm-lcr-meter-at-elektor-march-2013/?action=dlattach;attach=41082;image)

I'm not Rufus  ;), but you got it right. That is essentially the concept used in the design.
The signal comming out of Pin13/X is buffered and the signal on the other side of the range resistors (going to the inverting input of the opamp) is buffered as well.
These buffered signals are than fed into an instrumentation amplifier.

Martin
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 11, 2013, 08:45:35 pm
I'm not Rufus  ;), but you got it right. That is essentially the concept used in the design.
The signal comming out of Pin13/X is buffered and the signal on the other side of the range resistors (going to the inverting input of the opamp) is buffered as well.
These buffered signals are than fed into an instrumentation amplifier.

Martin

Hey Martin, thanks for the confirmation ! As an EE wannabe, I learned a lot and got quite few tricks from his sleeve posts, and one of my fav from many members around here as well. ;)

And thanks again for the additional info on handling the output, really, I haven't give a thought on that part yet.  :-+
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 11, 2013, 09:37:53 pm
Scratched my head quite hard thinking what you said here, made some rough sketch, something looks or similar like this Rufus ?

I don't think you quite have it. They call it a U/I converter but it is easier to think of it as a simple op-amp buffer as below.

The op-amp forces point X to the same potential as the +ve input, the +ve input is earthed so point X is forced to be earth also. Point X is called a virtual earth. If you push current in or out of point X the op-amp will compensate and keep it at earth.

If you add resistance in the op-amp feedback path it works the same but the op-amp output voltage has to change (a lot) more. The current in the feedback path has to match the current pulled or pushed from the virtual earth. The voltage across a resistor in the feedback path will be proportional to that current.

As long as you measure the voltage across a stable part of the resistance (Rref) it doesn't matter if there is additional unstable resistance (Rswitch) in the path.


Oh, and if the meter has high input impedance it doesn't matter if there is a small unstable resistance in series with it. One half of the 4052 feeds the op-amp output to the required resistor, the other half feeds the voltage from the required resistor to the meter.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 11, 2013, 10:03:54 pm
When You have silicon chip in your own country why do you need elektor ? .Other magazines beg borrow and steal articles from SC .A Person having a goldmine never understands the importance then a person who does not .I fancy that semtester they had few months back and now epe mag uk has it hee hee  .That was one awesome project .If you come to india stay with me  ;D

I offered my uWacth project to Silicon Chip first as a world exclusive, they turned it down too.

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 12, 2013, 06:26:51 pm
Rufus, thanks a lot !  Another new entry again from you written in my notebook.  :-+

Btw, mind point out what is the flaw of my implementation please ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus on March 12, 2013, 06:46:47 pm
Btw, mind point out what is the flaw of my implementation please ?

Your circuit looks more like a switchable gain inverting amplifier. The leftmost resistor isn't there, and the op-amp +ve input needs to be ground.

I don't know if you have seen the elektor circuit, if not the RLC-2 one here http://kripton2035.free.fr/Resources/RLC-2_rev.1.2.pdf (http://kripton2035.free.fr/Resources/RLC-2_rev.1.2.pdf) is very similar.

Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 13, 2013, 09:58:47 am
No, I haven't seen the circuit and not interested anymore.  :P

Thanks, and any comment on that RLC-2  circuit ? I mean the design wise for such LCR measurement ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 13, 2013, 11:57:26 am
well my first comments are : it's a gigantic puzzle ...
there is no kit available, only a main board pcb, everyone makes his own pcb for the supply and the display.
this board is smd quite only so it's very small. sure it's not a project for beginner.
you must find the good components to fit on the board and there are many versions of each one.
after I make mine I will make a review of this adventure !
also people that made it are mainly russians so the comments about it are difficult to translate.
the proradio web site has more than 450 pages of forum about it... I didnt read all ;)
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 13, 2013, 03:20:58 pm
Yeah, honestly I'm a bit overwhelmed just by looking at the circuit, its has quite high component counts.  :-\

Since you're making your own pcb, are you using the existing one or you're redoing from the scratch ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on March 13, 2013, 04:28:32 pm
I've been making the main rlc smd board that is on my repository
then I plan to install it in a hameg 8000 empty module so there is already a power supply at the back
only have to make some capacitor-inductors filters.
I will only make a pcb for the lcd and buttons front plate. that one will be made at home.
the main rlc board fits fine in an hameg box.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on March 14, 2013, 01:07:14 am
Which program are you using to redraw the circuit for the pcb ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: EEVblog on March 14, 2013, 01:50:55 am
Yeah, honestly I'm a bit overwhelmed just by looking at the circuit, its has quite high component counts.  :-\

My "simple" uSupply USB has over 50 resistors on it!
Some designs just take what they take.

Dave.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV 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
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: daveatol 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
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: vivaT 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.

Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on May 03, 2013, 04:42:54 am
The Project is open source..
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: boneDragon 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Zad 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Vgkid on June 30, 2013, 11:45:30 pm
For the same money I would grab this:
http://www.ebay.com/itm/GENERAL-RADIO-GENRAD-1658-RLC-Digibridge-Component-Test-Good-Condition-/200881249225?pt=LH_DefaultDomain_0&hash=item2ec5749bc9 (http://www.ebay.com/itm/GENERAL-RADIO-GENRAD-1658-RLC-Digibridge-Component-Test-Good-Condition-/200881249225?pt=LH_DefaultDomain_0&hash=item2ec5749bc9)
I own one, and it's big brother.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: quantumvolt 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 (http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf).


(http://cache.ourdev.cn/bbs_upload782111/files_35/ourdev_600061HGRXP8.jpg)


Source http://mrl.upesh.edu.pk/facilities/lcr_meter.html (http://mrl.upesh.edu.pk/facilities/lcr_meter.html) (good read ...)
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kodi 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/ (http://radiokot.ru/konkurs/53/) . Simple, cheap, four wire. And uses LCD that costs beween $1 and $2. And fits in your pocket.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on November 25, 2013, 07:09:59 am
finished mine...measures as per specs.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kodi 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).
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV on November 26, 2013, 11:51:25 am
How much in total you have spent in building this ?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 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.


Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kodi 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on December 01, 2013, 04:59:40 am
Thanks. I meant lowest reliable measure = 100 nano Henry (nH) = 0.1 micro Henry (µH). I had a couple of 0.18uH 0805 ones amd meter is measuring .18~.19.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV 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.  :-//
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: mos6502 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rufus 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kodi 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.

Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: ElektroQuark on December 03, 2013, 09:51:21 am
Is the correct PCB available?
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: BravoV 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.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: Rubi 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
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kvresto on April 07, 2016, 01:18:37 am
Is anyone willing to share the micro firmware for the rest of us? Joining this Elektor crowd is a ridiculous cost. Poor old AU dollar :)

cheers
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on April 07, 2016, 10:50:21 am
..
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kvresto on April 08, 2016, 01:44:15 am
Thanks fqahmad66, this will be very useful.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kvresto on April 14, 2016, 06:35:40 am
Hi Everyone, as my question is related I thought I wont start another thread.

I want to ask a question on this subject (disclaimer: 1st time researching on this subject). Most (all) capacitor data sheets specify their values at a test frequency of 100Khz. Most LCR meters via posts on this site use just one frequency much lower the 100k, and I assume thats because it mostly makes the hardware required cheaper? Others use 2 or 3 different frequencies like the LCR meter from Elektor, and I’m assuming the different frequency selection is for the flexibility of testing a larger range of capacitors?

Can someone who has done this sort of thing explain some background theory on this, ie why use several frequencies, how does that affect the amplitude to the measured voltage across the capacitor, and range of components under test, and anything else of interest. I’ve simulated this on LTspice and examined the results, and am getting closer to a cct I can use for experimenting.

Thanks
kvresto
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: kripton2035 on April 14, 2016, 10:54:45 am
100khz is the frequency you find very often inside smps, so the frequency the capacitors are most often faced to.
but I think you're wrong, main datasheets give the esr at 120Hz for the capacitors
yes build a test instrument at 100KHz is more expensive to do so lots of instruments stops at 10khz
the elektor lcr meter is one of those.
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on April 14, 2016, 12:33:15 pm
Search for 'General Descriptions of Aluminum Electrolytic Capacitors' by Nichicon..ESR dose not change much from 10KHz to 100KHz.

..
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: borjsu on October 05, 2018, 04:51:27 pm
The LCR meter from elektor 2013 has been at least tested after 5 year in the basement. It was just to put he PCB together and download the latest firmware. Now begin my problems. First it is impossible to find the Set-up and Operating Instructions documents. Where can I find it? Next problem. The stand alone front panel is not show anything. When start-up the screen show the bootloader version and then it go back to the dark side.

Everything is ok when I connect the PC.

What to do? 
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: fqahmad66 on October 06, 2018, 03:33:40 am
Check starting with connector. Then PCB for shorts
Title: Re: 500 ppm LCR Meter at Elektor March 2013
Post by: borjsu on October 06, 2018, 06:50:03 am
Hello.
This was useful. I am now on board again and the display is working.
Thank's a lot for the documents.