DCR ,Turns

[Mike Sulzer]

How about you buy a few 1% resistors say 2.2k 4.7k and 10K and use them to check your meter calibration?

Send your customer the 1% resistors and see what he gets.

[Mike Sulzer]

If the customer has a expensive LCR meter, he may be measuring them at 120 hz or 1khz.

But that should read higher, not lower.

[mozz]

Yeah i got that backwards. I wound a pickup, measured it, let it cool, it went lower. Magnetized it, took my inductance reading then hit the botton for "R", it was different, then i realized i was on 1khz. 100hz or 120hz is closer to the DC resistance but still a little higher. Could be you are in Canada and it's cold, maybe he is leaving the pickups in his car overnight.

[nickb]

mozz - DC resistance is a quantity that is independent of frequency. If your instrument says otherwise then it's in error. I would not be surprised by a small variation as you change the measuring frequency and especially at higher frequencies due to the nature of imperfection of the technique used but it could vary either way. If the error is significant then the meter is bad.

What is the make and model of your meter?

[Mike Sulzer]

mozz - DC resistance is a quantity that is independent of frequency. If your instrument says otherwise then it's in error. I would not be surprised by a small variation as you change the measuring frequency and especially at higher frequencies due to the nature of imperfection of the technique used but it could vary either way. If the error is significant then the meter is bad.

What is the make and model of your meter?

Eddy current losses in a pickup can be signifiant at 1KHz, raising the apparent DC resistance if used for that purpose. DC resistance really should be measured with DC, but 120Hz is very close, as was said.

[jack briggs]

mozz - DC resistance is a quantity that is independent of frequency. If your instrument says otherwise then it's in error. I would not be surprised by a small variation as you change the measuring frequency and especially at higher frequencies due to the nature of imperfection of the technique used but it could vary either way. If the error is significant then the meter is bad.

What is the make and model of your meter?

the Extech 380193 would beg to differ...

[nickb]

the Extech 380193 would beg to differ...

The Extech is wrong. Period.

It uses a simple model of the device under test, which as Mike kindly pointed out, doesn't include things like eddy losses.

[mozz]

mozz - DC resistance is a quantity that is independent of frequency. If your instrument says otherwise then it's in error. I would not be surprised by a small variation as you change the measuring frequency and especially at higher frequencies due to the nature of imperfection of the technique used but it could vary either way. If the error is significant then the meter is bad.

What is the make and model of your meter?

At work right now but my LCR is a Stanford Research? It doesn't measure dc resistance, it has 4 frequencies to choose from. I was saying, I mistakenly tried to measure a pickup dc resistance and got a different figure than my benchtop meter, then I realized it was measuring at 120hz or 1khz. The OP said his pickups were measuring lower and thought maybe a lcr was involved, but it would read higher as was said. Pretty sure my lcr meter (and benchtop)is near cal but I have a few .1% resistors I can try.

[copperheadroads]

I have 1000's of the 1% metal film resistors & i tested a bunch of different values & my meters all test where they should & for any one who don't know Extech 380193 don't do DCR . I rarely use mine .

[Mike Sulzer]

The Extech is wrong. Period.

It uses a simple model of the device under test, which as Mike kindly pointed out, doesn't include things like eddy losses.

Right; it measures impedance at some frequency, and that is represented by two numbers, amplitude and phase, or real and imaginary, or expressed as two more useful quantities. For example, set the frequency to 120Hz, set it to measure inductance and series R, then you get very close to the dc resistance, as well as the L. It can only get right things that are well represented by two numbers since it does not make multiple frequency measurements and do the calculation necessary to derive information from those measurements. That is the purpose of other devices, such as the pickup measuring system that I discussed on this forum several years ago and more recently in more detail on the pickup measurement subforum on pro boards, where it is just one of several efforts underway.

[J M Fahey]

Just downloaded the Extech user manual and was shocked considering many people (and probably Mozz´s customer too) will consider it a general purpose resistance meter ... which it is not.

meaning it can probably measure a *resistor* well, if purely resistive either DC or any frequency should read the same by definition ... but it can NOT give a DCR value for any significantly inductive element, specially a Guitar Pickup.

Just thinking aloud: if customer is actually using al LCR meter sending him the 1% resistors is useless ... they will show the expected value.

Problem is, that does not make the meter any better to read a pickup DCR value.
Or to be more precise, it probably can ... but in a more complex way, while customer might be using it in a simplistic way, .... suitable for plain resistors only.

Suggest him he uses a *multimeter* instead, even a $2000 one if he wishes , but set to resistance scale.

Thinking aloud II : he most certainly listens with his eyes.
Pickup is gorgeous but then he read that SRV pickupa read 5700 ohms, while Jimi Hendrix´r are 5200 ... and he´s very angry because OF COURSE "he wants to sound like SRV, not like that old fart Jimi" or some other stupid nonsense like that.

[nosaj]

Just downloaded the Extech user manual and was shocked considering many people (and probably Mozz´s customer too) will consider it a general purpose resistance meter ... which it is not.

meaning it can probably measure a *resistor* well, if purely resistive either DC or any frequency should read the same by definition ... but it can NOT give a DCR value for any significantly inductive element, specially a Guitar Pickup.

Just thinking aloud: if customer is actually using al LCR meter sending him the 1% resistors is useless ... they will show the expected value.

Problem is, that does not make the meter any better to read a pickup DCR value.
Or to be more precise, it probably can ... but in a more complex way, while customer might be using it in a simplistic way, .... suitable for plain resistors only.

Suggest him he uses a *multimeter* instead, even a $2000 one if he wishes , but set to resistance scale.

Thinking aloud II : he most certainly listens with his eyes.
Pickup is gorgeous but then he read that SRV pickupa read 5700 ohms, while Jimi Hendrix´r are 5200 ... and he´s very angry because OF COURSE "he wants to sound like SRV, not like that old fart Jimi" or some other stupid nonsense like that.

But if you'd put any guitar(cheap or expensive) in either Jimi or SRV's hands they'd still sound like who they were. It's the fingers and soul they poured into the music.

nosaj

[Mike Sulzer]

meaning it can probably measure a *resistor* well, if purely resistive either DC or any frequency should read the same by definition ... but it can NOT give a DCR value for any significantly inductive element, specially a Guitar Pickup.

If you measure a pickup inductance at 120 Hz, you also can get a series resistance. If you set the meter to R, you get exactly the same resistance. So it can measure very close to the actual DC resistance on either the L or R setting. And it is expected to be just a bit high, not low.

[David Schwab]

One know it all customer I have has an $2000 meter at his work & his readings on my pickups are way lower than mine & about 600 ohm lower on a paf style pickup so he thinks my reading & meters are out of wack .

But it's your pickups. The readings are meaningless to anyone but you. Plus there is no standard for PAFs. Do your pickups sound good? That's what matters. People put pickups in guitars and play them, they don't sit there and measure them.

This is why I don't even publish DC resistance on my pickups.

[jrdamien]

But it's your pickups. The readings are meaningless to anyone but you. Plus there is no standard for PAFs. Do your pickups sound good? That's what matters. People put pickups in guitars and play them, they don't sit there and measure them.

This is why I don't even publish DC resistance on my pickups.

This. A thousand times, this.

Did the customer play the pickups or just measure the dc? You have to consider the absurdity of wanting to return something like a guitar pickup because the dc measurement is different from what's advertised without ever having played the pickup.

The whole "DC thing" has led people astray in understanding a pickup (and I used to be one of the lost). I always immediately tell customers that the DC is a simple way to ballpark output and little more. And I try to do it in such a way that doesn't lead to a very long conversation about why that is and why it doesn't matter and, ultimately, talk myself out of a customer.