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'[EE] Do it yourself LCR / Bridge Meter ?'
2011\03\07@222158 by Adam Field

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I was looking around for a DIY LCR meter, one that can measure not
only L and C, but hopefully ESR and phase too. Measurements up to
10kHz would be good, more would be great.

I found software called Visual Analyser which is a scope, function
generator and also an RLC meter.

http://www.sillanumsoft.org/ZRLC.htm

It looks pretty capable, and the hardware interface is very easy being
based on 2 op-amps.

I also found this from Circuit Cellar based on a dsPIC:

http://www.circuitcellar.com/microchip2007/winners/third.html

It has full schematics and source code, but alas, no PCB artwork. I
could draw up the PCB but I decided to ask the wisdom of the list if
they have any suggestions on an LCR meter (with ESR) available for
minimal ($100 USD) cost.

I already try to do measurements with my scope and function generator,
but it's a hassle and I find even my 10M ohm scope probes can change
the circuit enough that I have to account for it

2011\03\07@231010 by IVP

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Adam,

I'm making one of these. Have the board ready but not populated

http://home.clear.net.nz/pages/joecolquitt/SC_LC_meter_1_sm.gif

http://home.clear.net.nz/pages/joecolquitt/SC_LC_meter_2_sm.gif

The author acknowledges the prior work and versions by

Neil Hecht of http://www.aade.com

Phil Rice of http://www.marc.org.au

PCB and s/w from

http://www.siliconchip.com.au/cms/attachments/show.html?year=2008&month=May

Jo

2011\03\07@235754 by D. Daniel McGlothin

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> I found software called Visual Analyser which is a scope, function
> generator and also an RLC meter.
> http://www.sillanumsoft.org/ZRLC.htm

A similar circuit ($20 kit), from the cited prior work articles from QEX & QST is available at
http://wb6dhw.com/RLC_Meter.html .

No affiliation, except I have one awaiting a build.

Daniel

2011\03\08@090338 by Isaac Marino Bavaresco

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Em 8/3/2011 01:09, IVP escreveu:
{Quote hidden}

This design is "LC" only, not "RLC".

I built one based on this idea, it works very well. BUT not for
capacitors with inductive design (electrolytic, polyester, etc).
The circuit oscillates at very high frequencies (100s of kHz) and the
MCU measures the frequency and compares with a reference (C2 in this
circuit).

To get good precision, C2's value must be known with high precision, and
it must be very stable.

Besides, it gives you only the inductance or capacitance, nothing more.


Best regards,

Isaa

2011\03\08@141619 by Richard Prosser

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On 9 March 2011 03:03, Isaac Marino Bavaresco
<spam_OUTisaacbavarescoTakeThisOuTspamyahoo.com.br> wrote:
{Quote hidden}

There was a design in "Electronics World"  a few years back for a
capacitance & ESR meter. Part of an article about which capacitors
were most suitable for use in high quality audio amplifiers.  IIRC it
was supposed to be quite accurate and measure to low ESR levels. But I
don't think it covered inductance.

R

2011\03\08@160431 by IVP

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> This design is "LC" only, not "RLC".

The OP did ask for "hopefully" ESR and phase. There are quite
a few PIC-based ESR meters out on the web that could be added
to a PIC-based LC meter

The Circuit Cellar project looks good, but I've not downloaded
the details

> I built one based on this idea, it works very well. BUT not for
> capacitors with inductive design (electrolytic, polyester, etc)

That is covered in the text. One of the PCBs is an adaptor so
that SMT caps can be measured

Jo

2011\03\08@181443 by Isaac Marino Bavaresco

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Em 8/3/2011 18:04, IVP escreveu:
>  
>> This design is "LC" only, not "RLC".
> The OP did ask for "hopefully" ESR and phase. There are quite
> a few PIC-based ESR meters out on the web that could be added
> to a PIC-based LC meter
>
> The Circuit Cellar project looks good, but I've not downloaded
> the details


Good commercial LRC meters measure also D/Q of inductors and resistance
in the range of milli-ohms.


>> I built one based on this idea, it works very well. BUT not for
>> capacitors with inductive design (electrolytic, polyester, etc)
> That is covered in the text. One of the PCBs is an adaptor so
> that SMT caps can be measured
>
> Joe


The problem here is not between SMT/conventional, but the series
inductance of some capacitors interfering with the measurement.


Best regards,

Isaa

2011\03\09@034235 by Gál Zsolt

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Here is an alternative based on the previous mentioned LC meters:

http://www.hobbielektronika.hu/kapcsolasok/lcm3_alkatresz_mero_muszer_-_kit_lehetoseg.html

It measures series resistance of electrolitic capacitors and the
memory effect also. It is uses about 90kHz frequency for measureing
it. You can find the full documentation on that page. I offer google
translator for reading it.


-- ~~~~~~~~~~~~~~~~
http://galzsolt.zzl.or

2011\03\09@061839 by Isaac Marino Bavaresco

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Em 9/3/2011 05:42, Gál Zsolt escreveu:
> Here is an alternative based on the previous mentioned LC meters:
>
> http://www.hobbielektronika.hu/kapcsolasok/lcm3_alkatresz_mero_muszer_-_kit_lehetoseg.html
>
> It measures series resistance of electrolitic capacitors and the
> memory effect also. It is uses about 90kHz frequency for measureing
> it. You can find the full documentation on that page. I offer google
> translator for reading it.


At 90kHz, this meter will also not work correctly for most electrolytic
and polyester capacitors.

The commercial LCR meters I know use two test frequencies, 120Hz and 1kHz.


Isaac

2011\03\09@094301 by Gál Zsolt

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Which is that equipment where electrolitic capacitors are working on
120Hz and 1kHz?
If you have a normal DC power supply where the power line voltage goes
to a transformer and the output goes to a rectifier bridge. There
could be 100Hz or 120Hz. Does it matter the ESR in this type of power
supply? I think any little.
A most modern power supply has a DC/DC part where the operation
frequency are above 50kHz. In these application does matter the ESR,
because it makes heat by charge of the capacitor rapidly. So this
equipment is measureing near the operation frequency. I can imagine
the 1kHz in an audio amplifier, but that is another area.
I am using that equipment, which I offered you. It give more
information about electrolitic capacitor than a normal equipment. It
shows problematic capacitor well. It is helpful when I repair
something. Lot of people built this LC meter in my country and I can
read only positiv words about it.



2011/3/9 Isaac Marino Bavaresco <.....isaacbavarescoKILLspamspam@spam@yahoo.com.br>:
{Quote hidden}

>

2011\03\09@101255 by Isaac Marino Bavaresco

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Em 9/3/2011 11:43, Gál Zsolt escreveu:
> Which is that equipment where electrolitic capacitors are working on
> 120Hz and 1kHz?
> If you have a normal DC power supply where the power line voltage goes
> to a transformer and the output goes to a rectifier bridge. There
> could be 100Hz or 120Hz. Does it matter the ESR in this type of power
> supply? I think any little.
> A most modern power supply has a DC/DC part where the operation
> frequency are above 50kHz. In these application does matter the ESR,
> because it makes heat by charge of the capacitor rapidly. So this
> equipment is measureing near the operation frequency. I can imagine
> the 1kHz in an audio amplifier, but that is another area.
> I am using that equipment, which I offered you. It give more
> information about electrolitic capacitor than a normal equipment. It
> shows problematic capacitor well. It is helpful when I repair
> something. Lot of people built this LC meter in my country and I can
> read only positiv words about it.


I agree that electrolytic capacitors may work at higher frequencies, but
if you want to measure the value that is near to what is printed
on its body, you will need to measure using lower frequencies.


The professional RLC meters I have used all test at 120Hz and 1kHz, and
they give the capacitance and the ESR.

If you want to know the effective capacitance at a give frequency, then
it's is OK to test at that frequency.


Isaac



{Quote hidden}

>> -

2011\03\09@103325 by Michael Watterson

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On 09/03/2011 15:12, Isaac Marino Bavaresco wrote:
{Quote hidden}

The 120Hz (or usually 100Hz in Europe) and 1KHz is Historic from days of mains PSUs only and valve audio amps for up to 12kHz.

SMPSUs commonly use Electrolytics and  Audio amps can be flat to 22kHz, needing good decoupling from 1Hz to 100kHz
I think that 90KHz is thus a reasonable ESR test frequency. SMPSUs use 16kHz to 1MHz, often with much harmonics.

Electrolytics are about -20% to +50% tolerance and at 90kHz ought to be what it says on tin.

I have used the AADE (no ESR) and also have a similar PIC based L:/C only meter using Mica caps selected on test by expensive lab test gear as reference.

I fancy this design.

Of course a L/C that tests at 100kHz, 1MHz, 10Mhz and 100MHz would be nice. But I usually check ferrite and RF air cored coils at working frequency with a generator as performance at 40kHz has little reality to 10MHz or 300MHz with coils.

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