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Thread: DCR ,Turns

  1. #1
    Woodgrinder/Pickupwinder copperheadroads's Avatar
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    DCR ,Multimeters ,Number of Turns & Customers opinions

    I have customers inquiring about my pickups reading lower than they should.
    & out of spec & so customer returns them & on my multi meter which i own about 5 all read where my pickups should . I don't own a expensive meter the few i own are between $30 to $150 but all my meters basically have the same readings makes me think my reading are correct .
    I explain how to measure pickups & correct temp
    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 .
    & I'm most of us uses Elektrisola wire 42 poly & PE & winding a paf style pickup with 5150 x2 should end up around 7.8k to 7.9k
    Not 7.2k or 5600 turns x2 should be 8.8k to 9k . I wonder what is going on here & why customers are getting the lower readings .
    Last edited by copperheadroads; 02-21-2017 at 04:36 PM.
    "UP here in the Canada we shoot things we don't understand"

  2. #2
    Senior Member Jim Darr's Avatar
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    Could be temperature variations/inconsistencies, meter calibration, or range settings.

    I really wish people would get away from DC Resistance as an indicator of tone. Sure it has its place and is directional, but people (builders and players) often don't really understand what DC resistance does and doesn't do.
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  3. #3
    ToneOholic! big_teee's Avatar
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    You need some new customers, not new pickups!
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  4. #4
    I'm a member? nickb's Avatar
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    How about you buy a few 1% resistors say 2.2k 4.7k and 10K and use them to check your meter calibration?
    Experience is something you get, just after you really needed it.

  5. #5
    Supporting Member mozz's Avatar
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    If the customer has a expensive LCR meter, he may be measuring them at 120 hz or 1khz.
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    Senior Member salvarsan's Avatar
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    Quote Originally Posted by nickb View Post
    How about you buy a few 1% resistors say 2.2k 4.7k and 10K and use them to check your meter calibration?
    Having reference components, even only one, is a good idea.

    If you don't mind setting fire to ... (cough!) paying $9 for a single resistor, Mouser stocks Vishay metal film resistors (pdf link) in the .01% tolerance range.
    4.57k @ 0.01% means 4570 +/- 0.457 ohms.
    As it turns out, this specification is deceptively close to being useful.

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    Quote Originally Posted by salvarsan View Post
    Having reference components, even only one, is a good idea.

    If you don't mind setting fire to ... (cough!) paying $9 for a single resistor, Mouser stocks Vishay metal film resistors (pdf link) in the .01% tolerance range.
    4.57k @ 0.01% means 4570 +/- 0.457 ohms.
    How about this at Electronics Goldmine?
    Electronic Goldmine - 3 Piece Precision Calibration Resistor / Set A
    Nosaj

  8. #8
    Senior Member salvarsan's Avatar
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    Quote Originally Posted by nosaj View Post
    How about this at Electronics Goldmine?
    Electronic Goldmine - 3 Piece Precision Calibration Resistor / Set A
    Nosaj
    Sure. I suspect that a resistor value near that of pickup coils would be best.
    That leaves a lot of wiggle room, I'm guessing 1,000-10,000 ohms.

    Nice resource with the Electronic Goldmine site.
    Thx.
    As it turns out, this specification is deceptively close to being useful.

  9. #9
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    .

    Are they measuring the pickups in the guitar or on the bench? I seem to get different readings after installing due to some circuit loading.

    What signals are in the area; the pickup could be grabbing something creating weak voltages to skew the results too. Guitars on my repair bench seem to pick up noise from the power line outside the house and hum a bit through the amp.

    .
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  10. #10
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    Quote Originally Posted by jvin248 View Post
    .

    Are they measuring the pickups in the guitar or on the bench? I seem to get different readings after installing due to some circuit loading.

    What signals are in the area; the pickup could be grabbing something creating weak voltages to skew the results too. Guitars on my repair bench seem to pick up noise from the power line outside the house and hum a bit through the amp.

    .
    Or buyers remorse.

    Nosaj

  11. #11
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    Quote Originally Posted by nosaj View Post
    Or buyers remorse.

    Nosaj

    ...How expensive are these particular pickups?

  12. #12
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    FWIW;

    I have a Wavetek and 2xFluke DMMs. Both the Wavetek and one of the Flukes are recently calibrated. I also have some really cheap Chinese DMMS. The readings are pretty close between all of them, except on AC voltage, where the cheapo ones are marginally out (but not a deal-breaker).

    The leads me to believe that even a cheap DMM should give fairly accurate readings.

    A secondary check for your meter resistance reading is to connect a low-voltage DC supply to your pickup and measure the current as well as the voltage drop across your pickup using a pair of DMMs. Then work out the resistance using Ohm's Law. This should agree with your meter's resistance reading and is sometimes more accurate.

  13. #13
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    Quote Originally Posted by copperheadroads View Post
    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 .
    I think mozz is right. Considering the cost, it's probably an LCR meter, which is probably measuring "AC resistance" (not sure how that's distinct from impedance). Ask the customer for the model number of the fancy meter he's using.
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    Quote Originally Posted by John Kolbeck View Post
    I think mozz is right. Considering the cost, it's probably an LCR meter, which is probably measuring "AC resistance" (not sure how that's distinct from impedance). Ask the customer for the model number of the fancy meter he's using.
    Even a $2000 meter can be uncalibrated. How expensive the meter is does not mean it will be correct on readings.Along with asking for the model ask when it was last calibrated. Heck in this day and age have them video them testing it. You might see something they're doing that may not be correct.

    nosaj
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  15. #15
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    Quote Originally Posted by John Kolbeck View Post
    I think mozz is right. Considering the cost, it's probably an LCR meter, which is probably measuring "AC resistance" (not sure how that's distinct from impedance). Ask the customer for the model number of the fancy meter he's using.
    If he was measuring impedance/AC resistance then his readings would be considerably higher rather than lower, depending on the test frequency.
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  16. #16
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    Quote Originally Posted by nickb View Post
    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.
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  17. #17
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    Quote Originally Posted by mozz View Post
    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.
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  18. #18
    Supporting Member mozz's Avatar
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    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.
    Last edited by mozz; 02-24-2017 at 12:49 AM.

  19. #19
    I'm a member? nickb's Avatar
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    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?
    Experience is something you get, just after you really needed it.

  20. #20
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    Quote Originally Posted by nickb View Post
    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.
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  21. #21
    Senior Member jack briggs's Avatar
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    Quote Originally Posted by nickb View Post
    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...

  22. #22
    I'm a member? nickb's Avatar
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    Quote Originally Posted by jack briggs View Post
    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.
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  23. #23
    Supporting Member mozz's Avatar
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    Quote Originally Posted by nickb View Post
    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.
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  24. #24
    Woodgrinder/Pickupwinder copperheadroads's Avatar
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    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 .
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  25. #25
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    Quote Originally Posted by nickb View Post
    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.
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  26. #26
    Old Timer J M Fahey's Avatar
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    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.
    Juan Manuel Fahey

  27. #27
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    Quote Originally Posted by J M Fahey View Post
    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
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  28. #28
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    Quote Originally Posted by J M Fahey View Post
    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.

  29. #29
    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by copperheadroads View Post
    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.
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  30. #30
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    Quote Originally Posted by David Schwab View Post
    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.
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  31. #31
    Old Timer J M Fahey's Avatar
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    I thought this thread was already dead and buried, but because it keeps resurfacing:

    1) measure your DCR with a standard universally trusted multimeter such as a Fluke model xxx (insert proper number here).
    It will measure DCR by passing a known and calibrated value of DC current through it, measuring DC voltage drop across a series resistor of known value, then displaying such DC voltage in a display but calibrated in Resistance values, scale unit: Ohm.
    I know you know this, I´m trying to get through to a particularly obnoxious customer.

    2) just in case recheck with a couple other multimeters, value should be within 5% or less.

    3) then ship pickup.
    If customer complains, tell him to get a Flke *** (same model as yours and should be a very popular one, so either he has or can borrow one)

    If his value is within 5% (it should, or one of the Flukes is dead/broken/whatever) then smile and tell him "hope you enjoy it, bye bye"

    If he says the <$100 Flukes agree with you but the $2000 meter does not, ask him: "is it a multimeter or a bridge or what the heck?" If he answers "bridge" tell him: "whatever his displays does not apply, you guarantee DCR , not ACR or R derived from an AC measurement, period"
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  32. #32
    Pickup Maker David Schwab's Avatar
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    Plus people make the mistake of holding the meter probes on the pickup wires by pinching them in their fingers! Now the resistance of their body is in parallel. I get a reading of ~ 5 MEGOHM touching both probes. It will give a slightly lower reading on the pickup. I always use the little spring clip probes.
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  33. #33
    Woodgrinder/Pickupwinder copperheadroads's Avatar
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    Quote Originally Posted by David Schwab View Post
    Plus people make the mistake of holding the meter probes on the pickup wires by pinching them in their fingers! Now the resistance of their body is in parallel. I get a reading of ~ 5 MEGOHM touching both probes. It will give a slightly lower reading on the pickup. I always use the little spring clip probes.
    True , I do have one cheaper more basic meter that you hands has no effect on resistance ,unlike most of my meters .
    Very strange is could be a low battery causing the glitch
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