The Extech 380193 LCR meter has an optical+serial data cable so you might (in principle) collect the measurements on your workstation.
There are practical issues that show the 380193's 10+ year age.
1) It handles serial data requests only once per second, although the display updates 3 times/second.
2) Setting up the meter by serial line reliably takes 5 seconds.
3) If you send it a command too soon after setup, the Extech either stalls or is slow to stabilize.
4) You can request and get data before the meter has stabilized and must request 3 or 4 readings to identify outliers.
Comprehensively collecting R,L, and C at 120Hz and 1kHz is a 20-30 second chore, ---
3X as long as doing it by hand (assuming you don't log data).
An inductance data string for one of Steve Kersting's vanilla P90's looks like:
LRASA0854341605422996433363__________
and means
Serial Inductance = 8.543 H @1kHz
AC resistance = 16.05 kOhms,
Q factor = 3.336
To be fair, you could adequately characterize a pickup using only L and C measurements on the primary display with Resistance on the secondary.
I'm hoping Extech's newer version, the LC200, does a better job with the serial IO.
Three positives equal one negative?
Yeah. Right. Sure.
Correction: As Joe Gwinn noted, an LCR capacitance measurement on a guitar pickup is nonsense because the test frequency is not at resonance.
A meaningful characterization is DC Resistance, followed by inductance and AC resistance at 120 Hz and 1kHz.
I just pulled the trigger on the newer LCR200 and also expect its comm protocol document.
News at 11.
Three positives equal one negative?
Yeah. Right. Sure.
Extech graciously and quickly sent a protocol document for the LCR200 L/C/R meter.
Its data rate is 8x as fast as the 380193 that we know and love, and the data format is more compact.
That's 9600 baud, 8,N,1, 17 byte packets versus 1200 baud,7,E,1, 39 byte packets
It can also test at 10kHz and 100kHz although those measurements may be irrelevant for guitar pickups.
The laconic 57kB LCR200 RS-232 protocol document is appended below.
LCR-9184-RS232.pdf
Three positives equal one negative?
Yeah. Right. Sure.
But you have to do the dc resistance separately or hope that the 120 Hz measurement is close enough (which I expect it is in most cases for pickups). When you measure in the R position, the measurement is still made at one of the two frequencies. I accidentally verified this by measuring a woofer in a cabinet. You can hear it, and the measurement at either frequency is not the same as a true dc measurement made with a DVM.Originally Posted by salvarsan
Why do they have the "R" position? Beats me, maybe Joe knows.
I think the Extech gives you a resistance at a frequency, i.e, Rac.
A pickup at hand measures:
Rdc = 9.155 k, Temp = 77.9F,
Rac(120 Hz) = 9.303k
Rac(1kHz) = 15.64k
L(120Hz) = 8.933 H
L(1kHz) = 8.547 H
In round numbers, 150 ohms difference is about 90 feet of #42AWG, nearly 200 winds on a Strat pickup. They aren't close enough to fall within copper temperature coefficient effects, so yes, Rdc needs to be a separate measurement.
Joe Gwinn could probably tell us more about eddy current contributions from the data set.
Three positives equal one negative?
Yeah. Right. Sure.
So Rdc and Rac(120 Hz) are about 1.6% different. Are you confident that the two meters are mutually calibrated closely enough so that you believe it?
I searched on line but couldn't find a price for the LCR200 yet. Is it a lot more than the old 380193?
is this it?
https://www.google.com/search?q=exte...w=1333&bih=625
about $260
Quit being a nudge.
Yeah, they're good to 4 sig fig on the same resistor.
It's the essential difference between the 20,000 count LCR and a 50,000 count DMM.
Three positives equal one negative?
Yeah. Right. Sure.
It's enough more. $260 MSRP, lowest street price is $235.
Try Google Shopping for pricing, or find a vendor on the Extech site.
According to Extech the LCR200, while more capable (more test frequencies, improved accuracy, both AC and DC resistance), it's a "read-only" device -- you can't configure it over the serial line.
If you already own a 380193, the LCR200 is a minor improvement.
If you don't own an LCR meter, the LCR200 is the better choice.
Three positives equal one negative?
Yeah. Right. Sure.
Because they can. There are six ways to present the one measurement the meter makes, of complex impedance. Extech has no way to know what we care about, so they provide all six answers.
Exactly.
The eddy current load is proportional to Rac minus Rdc.A pickup at hand measures:
Rdc = 9.155 k, Temp = 77.9F,
Rac(120 Hz) = 9.303k
Rac(1kHz) = 15.64k
...
Joe Gwinn could probably tell us more about eddy current contributions from the data set.
Thanks, though I don't see anyone actually selling it for less than 260 so it may be a wait and see for me. It would certainly be fun to have.
My discussion with a local vendor:
"The best online price is $234. I want to buy locally. Can you match or beat $245 so the 6% tax doesn't bite too hard?"
They said: " $234. No tax."
I said: "Cash."
They said, "It's Monday. Pick it up Thursday."
Three positives equal one negative?
Yeah. Right. Sure.
Hmmm, I wonder what a group buy would do for the price? If the local place is paying "B Mark" (40% off "retail") then they have some room.
A 40% price break at 10 $260 units is $156.
Coordinating a group buy is not easy.
On reliable code for automating the 380193 data collection, I get sort of okay prototype code.[root@Adelie lcrmeter]# python RLtest03.py
Serial port 0 found. Init: 1200,7,E,1
Resistance test mode @ 120 Hz
Rac @120Hz: 9.287 K
Rac @120Hz: 9.289 K
Rac @120Hz: 9.287 K
Resistance test mode @ 1000 Hz
Rac @1000Hz: 15.609 K
Rac @1000Hz: 15.606 K
Rac @1000Hz: 15.609 K
Inductance test mode @ 120 Hz
L @120Hz: 8.928 H Q @120Hz: 0.7422
L @120Hz: 8.928 H Q @120Hz: 0.7422
L @120Hz: 8.929 H Q @120Hz: 0.7422
Inductance test mode @ 1000 Hz
L @1000Hz: 8.540 H Q @1000Hz: 3.343
L @1000Hz: 8.539 H Q @1000Hz: 3.339
L @1000Hz: 8.539 H Q @1000Hz: 3.339
Three positives equal one negative?
Yeah. Right. Sure.
I emailed my local distributor about matching the 234 price and they responded asking for a link to that price. And yes a group buy will be like pulling teeth around here.
Passive Component LCR Meter [LCR200] - $233.99 : Azhtech, Your Qualified Resource for Test Equipment
Test Equipment Depot (Melrose, MA) also sells on eBay:
http://www.ebay.com/itm/Extech-LCR20...#ht_1233wt_907
You can contact TestEquipmentDepot directly and request their eBay price.
Last edited by salvarsan; 08-14-2012 at 09:08 PM.
Three positives equal one negative?
Yeah. Right. Sure.
Just a quick note BK the Precision 879B LCR meter also does impedance,Theta, and ESR, Uses USB for connectivity and uses SCPI commands (mostly human readable) and is in the same price range as the LCR200.
Not that the LCR200 is a bad unit but if you want data logging and remote control it may be an option for you.
DON'T DO IT!!!!!
The 380193 is spec'd for a D factor <= 0.5 which allows it to give a halfway accurate inductance reading on pickups.
It just works, warts and all.
The LCR200 is spec'd at D <= 0.1, and will very likely give crap readings for our intended purposes.
In light of this, the LCR200 may be a case of "more features, less function".
B&K lost a lot of LCR meter market share to Extech until they made a meter that would handle the higher resistance of pickup-like coils.
Three positives equal one negative?
Yeah. Right. Sure.
Salvarsan,
I got the message loud and clear. Thanks for the head's up and taking one for the team as usual.
I have never been happy with anything I ever bought from B+K. So I no longer buy their stuff. There are better choices.
Hi Joe
What would you recommend
Cheers
Andrew
For a handheld LCR meter, the Extech 380193 if you need it now, because we know that the 380193 is suitable for our purpose.
One assumes that there are other suitable kinds of LCR meters being made, but we will need to identify and verify them. For this, the group can help by identifying makes and models that claim to measure the inductance of lossy coils (D exceeds 0.5 (equivalently, Q less than 2), at 1 KHz) so we can assess them and compare them.
The Extech 380193 was originally validated by comparison with a Maxwell-Wien Impedance Bridge in 2004. Such bridges were the mainstay of the national standards labs for about a century, until digital came along.
For other kinds of instruments, it varies.
Joe is too modest.
It was he who verified the Extech 380193's suitability for intended use.
Three positives equal one negative?
Yeah. Right. Sure.
Thank you for all of your hard work.
I don't see Extech 380193 claiming anything under a DF <0.5 Is it possible they had a hardware revision due to component availability and changed the device? Or maybe they are just looking to match the other makers accuracy?
The capacitance accuracy of the 380193 at @1K only states a DF <0.5 at 199.99μF everything else is stated at <.1
I always figured in a fixed frequency LCR reading of a pickup that it was a relative measurement anyway but my main source of income is at a medical electronics manufacture and our products are heavy in analog circuits so if you give me what you want bounds to test between I will validate any newer device I can borrow from friends.
I only have a few slightly over 100 sets of pickups in customers hands and they have mostly been p90/humbucker style so this is going to be a guess but I think at 1 kilohertz ~.45 is as high as I have seen on DF all were less than 4H at the same frequency. This was on an auction sourced HP 4262A with questionable calibration.
Is this a safe range of what you are looking for?
The HAMs seem to be doing DIY or small run VNA's like these days. I am surprised someone hasn't built one for plotting out pickups and tone stacks.
It's very easy to build an audio network analyser using a bridge circuit driven by your PC soundcard. The ones I'm familiar with drive the circuit with pseudo-random noise and perform a FFT of the output with averaging, but swept sine is used too.
You could get a "dynamic signal analyzer" from HP many years ago that worked like this. The speaker measuring device from Dayton is the same, it is basically a USB soundcard with a built-in bridge. I've been using the technique, minus the bridge, to test filters and tone controls for years.
The hard part is getting software to do it that's easy to set up, understandable and free. I use Spectrum Lab which is intended for ham radio applications, but can be configured to do almost anything. Better options are available, but they cost money.
"Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"
Some of us have Syscomp's CGR-101 USB scope.
It does network analysis, so I think a good add-on for it would extract data
from the Bode plot below resonance and calculate Inductance, perhaps
distributed capacitance at resonance, and whatever else we could think of.
While I used to think the software's having been written in Tcl/Tk was a
questionable choice, Tcl scripts execute very fast and are trivially
portable across different workstation platforms.
Three positives equal one negative?
Yeah. Right. Sure.
The manual that came with my Extech quotes D<0.5 for inductance. The manual is marked "380193 V1.6 10/03" on every page.
The most recent manual, marked "380193-EU-EN-V2.3-5/11", says the same thing. The D limit is in the first line of the relevant table.
The basic test is a 2-henry iron-core (laminated) inductor in series with a 10K resistor. One can measure the components individually, and see how close the instrument under test gets to the correct answer when presented with resistor and inductor in series.I always figured in a fixed frequency LCR reading of a pickup that it was a relative measurement anyway but my main source of income is at a medical electronics manufacture and our products are heavy in analog circuits so if you give me what you want bounds to test between I will validate any newer device I can borrow from friends.
The smaller the inductor and the larger the resistor, the more severe the test. My rough and ready test is a 2 H iron-core inductor in series with a 50 Kohm pot - how large a series resistance will the LCR meter tolerate without gross error?I only have a few slightly over 100 sets of pickups in customers hands and they have mostly been p90/humbucker style so this is going to be a guess but I think at 1 kilohertz ~0.45 is as high as I have seen on DF all were less than 4H at the same frequency. This was on an auction sourced HP 4262A with questionable calibration.
Is this a safe range of what you are looking for?
We have discussed such things too, but this approach is a bit complex for most pickup makers to find useful. It's really a research tool.The HAMs seem to be doing DIY or small run VNA's like these days. I am surprised someone hasn't built one for plotting out pickups and tone stacks.
OK I think we are just having a NASA style units conversion issue.
"(D exceeds 0.5 (equivalently, Q less than 2), at 1 KHz) "
D=.5 == Q=2 I thought you were saying we need Q to approch 1/2 or D needed to be larger than .5 e.g. D=.75 which is the same as Q = 1 1/3
The new BK unit claims to support D<.5 I have a friend who has one and I may have access to the new agelent units although they are at a much higher price point than the Extech units.
I poked around at work at all our work is ultrasonic so I don't see any of these small units.
Thanks again for sharing this information.
The precise statement from the specs is a bit confusing. The hope is to find instruments that will measure fairly lossy inductors with reasonable accuracy. The spec are usually for ~1% basic accuracy, but for pickups 5% is plenty, so if the instrument is well designed, it will work OK and give consistent results even if at the edge of its spec limit.
To summarize, we are looking for instruments that claim to work with the lowest values of Q (equivalently, the highest values of D).
It would be interesting to know, but B&K cuts far to many corners for my taste, so I'd try using the instrument for a while, to find the unexpected gotchas. Like really slow measurement speeds, a common problem.The new BK unit claims to support D<0.5 I have a friend who has one and I may have access to the new agilent units although they are at a much higher price point than the Extech units.
I have built and used a current to voltage converter for this purpose and discussed many of the results on this forum. My thinking now is that one needs no special purpose hardware for this at all: a good quality two channel sampler intended for music recording into your computer is all the hardware necessary when used with good software.
I will try to post some results in the next couple of weeks.
Don't forget that the meter reads AC resistance, not DC. I find this ability is highly useful and its the first thing I look at with pickups. I'd be curious though to know if AC resistance at 10khz has any use at all. 10khz is kind of above almost everything in the pickup world. I really love the Syscomp gear I got, it gives me a good picture of what the LCR meters don't see in the higher frequencies.....
http://www.SDpickups.com
Stephens Design Pickups
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