Extech tutorial

[Achiles]

I´ve read alot things about the use of extech and some of them makes me confused.
can somone please post some kind of extech tutotial ?
Some kind of "Pickup datasheet log" or "Pickup autopsy datalog" would be nice.

[salvarsan]

Press ON
Toggle parallel mode by pressing PAL/SER until display says "PAL"
Select inductance mode by pressing L/C/R until display says "H" in lower right corner
Select AC resistance mode by pressing Q/D/R until display shows an omega in upper right corner
Toggle test frequency between 120 Hz and 1000 Hz as desired (test at both frequencies).
Connect leads to a coil.

The Extech 380193 User Manual is attached.

[David King]

I think Belwar posted a lot of Extech readings in some posts a few years back. Mr Candy I think may also have posted something along those lines last year as well.

[Achiles]

Tanx David,Salvarsan should i read C/R after L to?
Lets say we are measuring a HB umbalanced coil,
is it a good idea to measure both coils individually?
I just start to playing and that is the way i´m doing it.

[Mike Sulzer]

Tanx David,Salvarsan should i read C/R after L to?
Lets say we are measuring a HB umbalanced coil,
is it a good idea to measure both coils individually?
I just start to playing and that is the way i´m doing it.

You cannot measure the capacitance of a pickup coil because the inductance dominates. The inductance of humbucker coil is best measured at 120 Hz rather than 1000 Hz because of eddy current losses that make errors in the measurement at the higher frequency frequency. At 1000 Hz, the pickup circuit is an inductor with a series resistor, the coil resistance, with a series resistor and inductor in parallel. The last part is a reasonably accurate representation of the effect of the eddy currents. The Extech can handle either a series loss, as used with the pickup coil at 120 HZ, or a parallel loss, but it cannot handle a circuit with both. At 120 Hz, the parallel loss is small, and so you can get a good reading of the inductance in the series mode.

[FunkyKikuchiyo]

There was a spreadsheet online of a whole mess of data collected on pickups that is really handy to reference when you have an LCR meter handy. The original data wasn't collected with an Extech, but it isn't far off. I really like it because the pickups they measure are common ones and make for good comparisons. I'd link it, but all I'm finding are dead links, sorry...

[ScottA]

You cannot measure the capacitance of a pickup coil because the inductance dominates. The inductance of humbucker coil is best measured at 120 Hz rather than 1000 Hz because of eddy current losses that make errors in the measurement at the higher frequency frequency. At 1000 Hz, the pickup circuit is an inductor with a series resistor, the coil resistance, with a series resistor and inductor in parallel. The last part is a reasonably accurate representation of the effect of the eddy currents. The Extech can handle either a series loss, as used with the pickup coil at 120 HZ, or a parallel loss, but it cannot handle a circuit with both. At 120 Hz, the parallel loss is small, and so you can get a good reading of the inductance in the series mode.

In practice, I generally see pretty good agreement between the inductance at 120 and 1000 Hz in the series mode with the Extech, at least below about 10 H.

For example, the stuff I've been looking at the last couple of days represents an inductance range of about 4-8 H. For 1 measurement each of 25 different configurations, forcing the fit through the origin, I get:

H_1000Hz = 1.0003 x H_120Hz

with an R² of 0.9999.

Although the configurations in this particular dataset would be less influenced by eddy current effects and also have relatively high resonant frequencies. Looking at a larger range of data, I would say that as eddy current effects increase, the 1000 Hz measurement starts to diverge a bit, but still is usually within 5% or so.

[jmaf]

Achiles, I found the Extech manual here, will get it to you soon - but it's not really useful, Salvarsan and others have provided more info than it's in it.

Not wanting to hijack Achiles' thread, (I think he may have similar questions?), if anyone could please help out:

1) When reading a capacitor, the R that appears on the secondary reading is different than if you test the capacitor via the main R function. Why? (Same frequency.)

2) About question 1, when measuring R for a capacitor, is that the ESR?

3) The Q factor should be reactance divided by DCR, correct? The higher the Q, the more reactance to resistance ratio, right? Good pickups have high reactance, low DC resistance?

4) Raising the frequency from 120 to 1K seems to multiply Q, but not by 8.3, what ratio is Q increasing when we increase the frequency 8.3 times from 120 to 1k?

5) If I take a function and test something unexpected with it, are the readings valid? Testing inductance in a guitar cable for example? Capacitance in a coil? Or will the inductive reactance in a iron core coil for example ruin the capacitance reading in all cases like Mike Sulzer explained? If I read some inductance on a resistor, is that reading correct?

Thanks in advance for any pointers.

[Mike Sulzer]

Scott, your measurements show how good the Extech meter is. Measuring inductance when the inductive reactance is low (low frequency, therefore low Q) is not so easy. One reason often given for using the higher frequency is to avoid just such inaccuracy. But it is not necessary to do that.

In practice, I generally see pretty good agreement between the inductance at 120 and 1000 Hz in the series mode with the Extech, at least below about 10 H.

For example, the stuff I've been looking at the last couple of days represents an inductance range of about 4-8 H. For 1 measurement each of 25 different configurations, forcing the fit through the origin, I get:

H_1000Hz = 1.0003 x H_120Hz

with an R² of 0.9999.

Although the configurations in this particular dataset would be less influenced by eddy current effects and also have relatively high resonant frequencies. Looking at a larger range of data, I would say that as eddy current effects increase, the 1000 Hz measurement starts to diverge a bit, but still is usually within 5% or so.

[Mike Sulzer]

1, 2. Yes, if you have resistance in series with the "ideal" capacitance, you cannot measure that at dc since the impedance of the capacitor is infininte. So the effects of ESR are frequency dependent.

3. The Qs of pickups vary, depending on the required sound. It will not sound good if you make it too high.

4. Depending on the pickup core design, the effects of eddy currents will vary. These effects are frequency dependent and affect the Q reading.

5. Usually the inductive reactance of a resistor is so low compared to the resistive that even the Extech cannot read it with good accuracy. Knowing when to trust that kind of measurement is not so easy.

Achiles, I found the Extech manual here, will get it to you soon - but it's not really useful, Salvarsan and others have provided more info than it's in it.

Not wanting to hijack Achiles' thread, (I think he may have similar questions?), if anyone could please help out:

1) When reading a capacitor, the R that appears on the secondary reading is different than if you test the capacitor via the main R function. Why? (Same frequency.)

2) About question 1, when measuring R for a capacitor, is that the ESR?

3) The Q factor should be reactance divided by DCR, correct? The higher the Q, the more reactance to resistance ratio, right? Good pickups have high reactance, low DC resistance?

4) Raising the frequency from 120 to 1K seems to multiply Q, but not by 8.3, what ratio is Q increasing when we increase the frequency 8.3 times from 120 to 1k?

5) If I take a function and test something unexpected with it, are the readings valid? Testing inductance in a guitar cable for example? Capacitance in a coil? Or will the inductive reactance in a iron core coil for example ruin the capacitance reading in all cases like Mike Sulzer explained? If I read some inductance on a resistor, is that reading correct?

Thanks in advance for any pointers.

[salvarsan]

Tanx David,Salvarsan should i read C/R after L to?
Lets say we are measuring a HB umbalanced coil,
is it a good idea to measure both coils individually?
I just start to playing and that is the way i´m doing it.

If it's unbalanced, YES, measure both individually. Good quality control that way.

The 1kHz vs. 120 Hz AC resistance difference tells you about the eddy current contributions. They let you know more about how consistent your pickup building is.

[Mike Sulzer]

Let's look at a coil that is a bit different from the usual pickup coil as an example of how to use the Extech and understand the results.

The coil in question is intended as an individual string pickup. It uses a humbucker slug as a core and a bobin intended for use swith an EP-13 ferrite core. It is necessary to ream it out slightly for use with the slug. I wind 2,000 turns of #43 wire onto it. With no core, at 120 Hz in series mode, I measure 17.02 mH with a resistance of 322.6 ohms, although this varies with time as the temperature changes. This is a Q of about .04, which is quite low, and so it would not be surprising if this is not too accurate. At 1 KHz I measure 16.69 MH with a Q of about .33. The inductance measurement has changed by about 2%, and since there are no eddy currents, this is probably the result of the low Q at 120 Hz. But even so, this is a pretty small error!

When the core is inserted, the inductance rises to 70.15 MH, 120 Hz, series mode, about four times greater. (The relative increase in a normal pickup coil is somewhat less since the cores do not entirely fill the available space.) I measured 320.2 ohms at this time; my multimeter gave 320.6, closer that I have any right to expect, but a good indication that at 120 Hz, the dominant loss in the coil is the series resistance. At 1000 Hz, the inductance drops by 6.5% and the resistance rises to 365.6 ohms. Why? Well, the short answer is eddy currents, but how does this happen?

The Extech can be thought of as measuring an amplitude and a phase. Or you can think of it as the projections onto the x and y axes, the real and imaginary parts. The interpretation of this measurement is a function of the meter settings, and the assumption is that you have a reactance, either an L or a C with a resistor in either series or parallel. You cannot analyze both at once. The eddy current load goes in parallel with the inductance, and so this is in conflict with the series resistance of the coil. Also the parallel load is not a pure resistance, but has an inductance in series. So the effect of the eddy currents is to reduce the magnitude of the measured impedance and reduce the angle, that is, move it in the directino of the real axis. This will certainly reduce the measured inductance, and probably increase the measured resistance. This rells you something about the eddy current loss. But it does not allow you to compute the value of the parallel impedance. That would require additional measurements.

[Joe Gwinn]

...Also the parallel load is not a pure resistance, but has an inductance in series. So the effect of the eddy currents is to reduce the magnitude of the measured impedance and reduce the angle, that is, move it in the directino of the real axis. This will certainly reduce the measured inductance, and probably increase the measured resistance. This rells you something about the eddy current loss. But it does not allow you to compute the value of the parallel impedance. That would require additional measurements.

The Extech makes one measurement, of complex impedance, and then mathematically fits that impedance to the circuit implied by the selected SER or PAR circuits, so one can deduce one from the other.

The reason to use 1000 Hz is simply that it's in the audio range, and is the standard test frequency for audio. The KHz range is important even if the fundamental is 100 Hz, because what matters are the harmonics in the kilohertz range.

[Mike Sulzer]

The reason to use 1000 Hz is simply that it's in the audio range, and is the standard test frequency for audio. The KHz range is important even if the fundamental is 100 Hz, because what matters are the harmonics in the kilohertz range.

No, that is not the reason, not even close. You are completely ignoring the context within which the measurement occurs.

For example, consider the measurement of a resistor. The context here is that although all resistors have inductance and capacitance as well as resistance, a measurement made at dc is all you need in most cases for audio. Sometimes you need more, but usually your multimeter tells you all you need to know.

The context of pickup coil measurement is much more complicated. It can only be determined by making measurements over the whole useful frequency range of such devices and constructing a model containing the essential components. The result of this model is the knowledge that the Extech measurement at 120 Hz yields the inductance of the coil and its series resistance to good accuracy. The measurement at 1000 Hz adds some information about the degree of eddy current loss, determined by how much it deviates from the 120 Hz measurement.

It appears that you do not agree with this. You can give some beef to this disagreement by making measurements
and analyzing the results in order to show that your understanding, whatever it might be, is correct. However, I am confident that if you put in the work and think about it correctly, you will come to agree with my understanding.

[RedHouse]

Aw geez, here we go again!

[Joe Gwinn]

You asked why people measure audio components at 1 KHz, and I answered. You replied that they should not do this, that things are far more complex, et al. You are no doubt correct, but those bad people don't care. They need and want a simple measurement. And they outnumber you.

[Mike Sulzer]

When I go back and reread the post in question, the only question I see is a rhetorical one: why is the measured inductance value different at 1KHz from 120 Hz? I explained this with eddy currents, the explanation you found some time ago. What's this about being outnumbered by bad people who want to measure at 1 KHz because it is a standard? That sounds like something out of some B movie pychological thriller. Standard or not, it is 120 Hz on the Extech that gives the inductance of the pickup coil with good accuracy. All those bad peole who want a simple measurement need only push the frequency button and use 120 Hz, and then use the 1 KHz measurement as an indicator of the size of the effect of eddy currents.

Extech intended the 120 Hz setting for large electrolytic capacitors, but an unintended consequence of including that frequency is to provide a simple, accurate way of measuring the inductance of a pickup coil. Way back four or five yers ago when I first read your posts about eddy currents, I suggested avoiding those effects when measuring coil inductance by using the lowest frequency possible in the measurement. You objected rather strongly, apparently thinking I meant something like 1 Hz. No, 120 Hz is good.

The inductance is a frequency independent quantity, and so it makes sense to measure it at a frequency at which other components in the pickup model circuit to not have a significaant effect (except for the series resistance, which the Extech can handle simultaneously). Parallel loss is important at 1 KHz for pickup coils that use a significant amount of conducting material. When energy storage is the issue, defining a frequency dependent effective inductance can make sense. With pickups, it is the frequency response that is important, and so for that we need a good model of the circuit. A key component is the coil inductance.

You asked why people measure audio components at 1 KHz, and I answered. You replied that they should not do this, that things are far more complex, et al. You are no doubt correct, but those bad people don't care. They need and want a simple measurement. And they outnumber you.

[SkinnyWire]

I just finished measurements for a 14.4k pickup from a large builder that was supposedly stock in a high dollar custom shop guitar. Here are the results, posted for those interested and maybe to foster further discussion:

Equipment:
Raytek MiniTemp MT6 IR Thermometer
ER Mu115 DVM
Extech 380193 LCR Meter
Syscomp CGR-101 Oscilloscope/Network Analyzer

Measurements:
Ambient Temperature = 75.5°F
DC Resistance = 14.46 kΩ

Inductance and AC Resistance from LCR Meter:
L Series 120 Hz = 8.62 H
RAC Series 120 Hz = 14.66 kΩ
L Series 1 kHz = 8.37 H
RAC Series 1 kHz = 23.66 kΩ
L Parallel 120 Hz = 50.32 H
RAC Parallel 120 Hz = 17.59 kΩ
L Parallel 1 kHz = 10.06 H
RAC Parallel 1 kHz = 141.0 kΩ

Syscomp CGR-101 Oscilloscope/Network Analyzer:
Resonant Frequency via Driver Coil and Lissajous Figure

f0 = 4.17 kHz

Circuit Components for Inductance Calculation
Added Capacitance = 1003 pF
Series Resistor = 98.3 kΩ
Resonant Frequency

f0 = 1.56 kHz

Calculated Inductance

L= 1/C (1/(2πf_0 ))^2= 1/(1.003 x 〖10〗^(-9) ) (1/2π1560)^2

= 10.38 H

Stray Capacitance

C= 1/L (1/(2πf_0 ))^2= 1/10.38 (1/2π4170)^2

= 140 pF

I believe the stray capacitance calculation is reasonable, considering the capacitance per foot of the hookup cable. The calculated inductance is pretty close to the Extech in Parallel/1kHz mode.

[Joe Gwinn]

Measuring audio components at 1 KHz has been the de facto standard since the 1930s.

[Rosewood]

Can someone explain D and Q on the extech as far as pickups go? Maybe on the 3rd grade or monkey level.

[Achiles]

R from L/C/R and R from Q/D/R , what is the diference?

[Joe Gwinn]

D and Q are the inverse of one another: D=1/Q.

[Joe Gwinn]

There is one underlying measurement, that of in-phase and quadrature impedance.

If one measures a resistor, the impedance is all in-phase. The quadrature impedance in infinite or nearly so.

If one measures an ideal capacitor or inductor, the impedance is all quadrature, the difference being if the resulting current leads or lags the driving voltage. The in-phase impedance is infinite or nearly so.

If one measures a practical component, such as a pickup, there is a mixture of resistance and inductance, and there will be significant in-phase and quadrature impedance components.

We usually express this as an inductance and a series AC resistance. But one may express the same thing as a inductance with a Q or D. Nothing real has changed; it's an alternative way to express the same thing.

[Stratz]

Hi all, I bought an Extech 380193 in early 2010 and recently the LCD display starting acting up so I sent it out for repair.
When I got it back I noticed that it now has an anti glare type matte finish on the screen which it did not have before.
It's very annoying and makes the screen difficult to read.

Does anybody else have a Extech 380193 with this type of finish on the LCD screen?

Thanks
Rob

[dai h.]

is it a finish or perhaps transparent vinyl (which you can remove)?

[Stratz]

is it a finish or perhaps transparent vinyl (which you can remove)?

Well, I tried to pick at a corner to see if it was a protective covering but it doesn't appear to be removable.

I'll see if I can post a picture later today.

Anybody else with a 380193 model care to comment?
Thanks.
Rob

[Mike Sulzer]

Well, I tried to pick at a corner to see if it was a protective covering but it doesn't appear to be removable.

I'll see if I can post a picture later today.

Anybody else with a 380193 model care to comment?
Thanks.
Rob

Yes. This is the worst display I have ever seen on any professionally designed instrument. To begin with, the secondary information is too small, requiring extreme focal correction for old eyes. With that stupid blurry stuff over it, I have to get within a few inches in order to read it, even in bright light. Or I can remove all correction and use my natural extreme near sightedness. This is a fairly new instrument, and I nearly sent it back. Determining the mode of operation or the frequency is just way too difficult.

I tried lifting a corner, but stopped for fear of making it worse. I am tempted to just remove the plastic all together.

[Joe Gwinn]

Well, I tried to pick at a corner to see if it was a protective covering but it doesn't appear to be removable.

I'll see if I can post a picture later today.

Anybody else with a 380193 model care to comment?

Haven't had the problem as the LCD hasn't failed.

I would call Extech up and ask before starting to fiddle. They're in the Boston area.

[SonnyW]

Yes. This is the worst display I have ever seen on any professionally designed instrument. To begin with, the secondary information is too small, requiring extreme focal correction for old eyes. With that stupid blurry stuff over it, I have to get within a few inches in order to read it, even in bright light. Or I can remove all correction and use my natural extreme near sightedness. This is a fairly new instrument, and I nearly sent it back. Determining the mode of operation or the frequency is just way too difficult.

I tried lifting a corner, but stopped for fear of making it worse. I am tempted to just remove the plastic all together.

Mine is old and the display is fine, but just as a thought, has anyone considered trying the software that comes with most of these? Mine came with a CD and a cable. I have an old laptop that I keep at my bench, and usually an external display there as well and I seldom have to look at the display on the Extech. It is replicated on the PC display. It was pretty straightforward to set up. I did it to automatically record my test data into an excel spreadsheet, but I leave it running and use the PC display even when I am not recording data.

[ScottA]

The display on mine is OK, too.

I got mine used off of ebay (really cheap, too!).

Sonny, is there any way I could get that software? I would really like to automate my measurement collection. I measure every pickup for final QC and the hand translation gets old after awhile, as well as providing plenty of opportunities for error.

Thanks,

Scott

Mine is old and the display is fine, but just as a thought, has anyone considered trying the software that comes with most of these? Mine came with a CD and a cable. I have an old laptop that I keep at my bench, and usually an external display there as well and I seldom have to look at the display on the Extech. It is replicated on the PC display. It was pretty straightforward to set up. I did it to automatically record my test data into an excel spreadsheet, but I leave it running and use the PC display even when I am not recording data.

[Stratz]

Yes. This is the worst display I have ever seen on any professionally designed instrument. To begin with, the secondary information is too small, requiring extreme focal correction for old eyes. With that stupid blurry stuff over it, I have to get within a few inches in order to read it, even in bright light. Or I can remove all correction and use my natural extreme near sightedness. This is a fairly new instrument, and I nearly sent it back. Determining the mode of operation or the frequency is just way too difficult.

I tried lifting a corner, but stopped for fear of making it worse. I am tempted to just remove the plastic all together.

Thanks Mike. This matte finish cover must be something new as the old screen didn't have it.

Joe, I did contact Extech when I got it back. The tech said that they don't sell the meter with a non glare, matte finish screen. No surprise there.

Scott, you can download the software here at the bottom of the page. VER 1.3 (15.6MB) is the newest (perhaps the only version) as far as I can tell. You will need the optical cable (my meter came with it) and a PC with a serial port. I run it on Win XP-SP2 and it works good.

I don't like the new LCD cover it as much as the original but I can live with it.

Thanks to all for your help.
Rob

[SonnyW]

The display on mine is OK, too.

I got mine used off of ebay (really cheap, too!).

Sonny, is there any way I could get that software? I would really like to automate my measurement collection. I measure every pickup for final QC and the hand translation gets old after awhile, as well as providing plenty of opportunities for error.

Thanks,

Scott

That's what I use it for and it is great. You can export to a spreadsheet, set go-no go etc. The software is a runtime adaptation of LabView, I think I read somewhere. Mine came with a CD and a cable. You can download the software free from extech here:

Extech Instruments - Software Downloads

but you will need the special cable if yours didn't have it. It is an optical to serial RS232 cable. If you don't have the cable, you can order both the cable and the CD from TestExtra (which is where I got my meter from. Scroll down to the bottom. It's $19.99

Extech 380193 LCR Meter, extech 380193 passive component lcr meter

[Joe Gwinn]

That's what I use it for and it is great. You can export to a spreadsheet, set go-no go etc. The software is a runtime adaptation of LabView, I think I read somewhere. Mine came with a CD and a cable. You can download the software free from extech here:

Extech Instruments - Software Downloads

but you will need the special cable if yours didn't have it. It is an optical to serial RS232 cable. If you don't have the cable, you can order both the cable and the CD from TestExtra (which is where I got my meter from. Scroll down to the bottom. It's $19.99

Extech 380193 LCR Meter, extech 380193 passive component lcr meter

I think these optical RS232 cables are universal and standard.

You can also talk to a meter with a computer having a real serial port, and Hyperterm. The protocol isn't complex, and is all ascii. Start with a "?". Extech has it documented somewhere.

[SonnyW]

I think there optical RS232 cables are universal and standard.

You can also talk to a meter with a computer having a real serial port, and Hyperterm. The protocol isn't complex, and is all ascii. Start with a "?". Extech has it documented somewhere.

First Joe, let me say you have helped me more with understanding the Extech meter and its uses than anyone else has. I'm very grateful for that. But I have never seen another cable just like this one, and I have seen a lot of fiber cables in my former work. Of course, on the other hand, I don't get around much anymore. The meter has an optical interface that is not TOSlink or anything optical like I have seen before. It has three connections- looks like a transmit/ recieve/ key combination. It might be a universal thing though, in another meter interface world that I don't travel in. Anyway I did a little googling and came up with this cable for $10 that is the same as the one I have. I don't know how many of these he has.

IR2 Optical Interface RS-232C Cable - $10.00 : Bryan Kollar!, The Computer Guy

I'm sure that once you get connected to the meter, it would probably work fine with the hyperterminal interface, but on the other hand the software from Extech is free and already highly developed. One does need to press the button on the meter three times to record all the available data to the PC.

[the great waldo]

Hi All

Does anyone know if it's worth upgrading to an extech lcr200 from their normal model. The test frequencies go up to 100 khz ?

Cheers

Andrew