dazz
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Post by dazz on Dec 22, 2017 10:57:30 GMT -5
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Post by antigua on Dec 22, 2017 18:29:33 GMT -5
I think you're right, the appear the same as DS53 in all respects guitarnuts2.proboards.com/thread/7848/donlis-ds53-analysis-review . I've since installed that set in a Strat, I'm very happy with them. If sets in the 5k range, you could say these 6k sets are "hot vintage", similar to my ears to Fender Fat 50's, Lollar Blackface and the like. All the words used to describe those sets would fit here. I think the dramatic chamfer on the Donlis DS53 / FLEOR looks really cool, definitely distinctive. The other nice thing is that this set is spaced 52mm end to end, for all three, which is essentially Fender standard, so you won't have trouble swapping cover colors. Some Chinese Strat sets, like the Donlis DS51 have 50/51/52 pole spacing, and so it's much more of a task to find alternate different covers for them. |
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dazz
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Post by dazz on Dec 23, 2017 4:41:56 GMT -5
Thanks antigua.
I'll post some pics once they arrive
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dazz
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Post by dazz on Dec 23, 2017 8:17:47 GMT -5
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Post by JohnH on Dec 23, 2017 13:52:37 GMT -5
Wow! at that price, there's no point in not buying one! It looks like its a 'module', needing some building-out if you want to make it a more serviceable piece of kit, in a case. As for accuracy, a few tests on a handful of known parts will provide some confidence. I have a $50 multimeter that does LRC readings and measures 1% resistors and 5% capacitors to be inside their spec, and also pickup inductance where I have them of known values. This unit looks to be potentially better than that with lower ranges available. |
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Post by antigua on Dec 23, 2017 14:24:38 GMT -5
The important thing is that it have a low test frequency, because if the freq is too high, eddy currents will screw up the measurements. The famous Extech meter has 120Hz and 1kHz options, and there's really no use in using the 1kHz option, other than to see how far it diverges from the lower 120Hz measure. I don't see any spec as to the test frequency, that kind of bothers me. It seems to be described as a "transistor test" rather than an LCR meter, so the focus of the device is no on inductor testing. That being said, if this represented a way for guitarists to find inductance as easily as they find resistance, that would be a boon to this field, so I'll over one and see how it compares the the Extech's values. It will probably take a month to arrive, but considering it priced slightly above free... |
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dazz
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Post by dazz on Dec 23, 2017 14:28:45 GMT -5
Wow! at that price, there's no point in not buying one! It looks like its a 'module', needing some building-out if you want to make it a more serviceable piece of kit, in a case. As for accuracy, a few tests on a handful of known parts will provide some confidence. I have a $50 multimeter that does LRC readings and measures 1% resistors and 5% capacitors to be inside their spec, and also pickup inductance where I have them of known values. This unit looks to be potentially better than that with lower ranges available. Yeah, apparently these things have been quite popular for a while: www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/I wonder if this LCR-T4 will identify the pickups as resistors or inductors? We'll see. Also wondering if it can be used or "tricked" to display the pickup's capacitance and then calculate the theoretical peak resonance frequency? |
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dazz
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Post by dazz on Dec 23, 2017 14:35:15 GMT -5
The important thing is that it have a low test frequency, because if the freq is too high, eddy currents will screw up the measurements. The famous Extech meter has 120Hz and 1kHz options, and there's really no use in using the 1kHz option, other than to see how far it diverges from the lower 120Hz measure. I don't see any spec as to the test frequency, that kind of bothers me. It seems to be described as a "transistor test" rather than an LCR meter, so the focus of the device is no on inductor testing. That being said, if this represented a way for guitarists to find inductance as easily as they find resistance, that would be a boon to this field, so I'll over one and see how it compares the the Extech's values. It will probably take a month to arrive, but considering it priced slightly above free... If it helps, here's a link to the manual of the original design: github.com/svn2github/transistortester/blob/master/Doku/trunk/pdftex/english/ttester.pdf |
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Post by antigua on Dec 23, 2017 14:53:33 GMT -5
Wow! at that price, there's no point in not buying one! It looks like its a 'module', needing some building-out if you want to make it a more serviceable piece of kit, in a case. As for accuracy, a few tests on a handful of known parts will provide some confidence. I have a $50 multimeter that does LRC readings and measures 1% resistors and 5% capacitors to be inside their spec, and also pickup inductance where I have them of known values. This unit looks to be potentially better than that with lower ranges available. Yeah, apparently these things have been quite popular for a while: www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/I wonder if this LCR-T4 will identify the pickups as resistors or inductors? We'll see. Also wondering if it can be used or "tricked" to display the pickup's capacitance and then calculate the theoretical peak resonance frequency? That would be awesome, but the other side of that is that when you are assuming a fixed capacitance that includes a guitar cable, you can guesstimate the resonant peak just by looking at the inductance. For example: - High inductance; Seymour Duncan JB, 8H =2.0kHz given 470pF cable + 102pF intrinsic capacitance. - Low inductance; Seymour Duncan Jazz, an inductance of 4.1 = 3.2kHz , given 470pF cable + 102pF intrinsic capacitance. So for the PAF foot print, that represents something of a low to high extreme. You can guess reasonably closely where pickup's treble response will land by where along the spectrum the inductance is between 8H = 2kHz, and 4H = 3.2kHz. You might want a different set of reference points for Teles and Strats: - High inductance; Seymour Duncan SSL-5, 6.2H =2.2kHz peak with an assumed 470pF+140pF capacitance. - Mid inductance; Fender Texas Special bridge, 3.2H = 3.4kHz given a similar capacitance. - Low point of inductance; Fender CS 69, 2.1H = 4.1kHz with an almost identical capacitance to the SSL-5. So if you pull a Strat pickup and see an L of 2.5H, that's 400mH more than the CS '69 with a 4.1kHz peak, but 700mH below the Texas Special with a 3.4kHz peak, so you know off the top of your head that the peak is going to be in the very high 3kHz range. I've come to think in these terms just from having looked at dozens of measurements over the past couple years. |
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Post by antigua on Dec 23, 2017 15:03:01 GMT -5
One thing I forgot to mention is that only pickups with steel parts suffer this frequency sensitivity. Even if the test freq is 1kHz, it would still work fine for most Fender pickups, which are nothing but AlNiCo, copper wire and flatwork. If it turns out this thing is only of benefit to Fender guys, that's not the worst thing in the world. TBH, the Telecaster community has been the most receptive to technical analysis, by far.
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dazz
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Post by dazz on Dec 24, 2017 2:20:40 GMT -5
Another thing to give us hope: this thing runs an open source firmware that can be flashed using some inexpensive equipment, and there's a large community of knowledgeable guys at eevblog that may be willing to help us tweak it if it doesn't already do what we need out of the box ETA: I'm registering there to ask the relevant questions: www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/4300/ |
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dazz
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Post by dazz on Dec 24, 2017 4:07:30 GMT -5
Here's the chapter of the manual on inductance measurement. 8MHz? ouch
5.4
Measurement of inductance
The measurement of inductance values will be done as separate part with all found resistors with
less than 2100Ω. The methode of measurement is based on the growing of current by formula
L
Il = Imax · (1 − exp −t ) after switching on the current. The time constant τ = R is proportional
τ
to the inductance L, but reverse proportional to the resistor R. The current can only measured
indirectly with the potential drop of a resistor.
Unfortunately the time constant will be reduced additionally by the relative high resistance 680Ω,
for that the measurement of little inductance values is additionally made difficult with the 8MHz
clock. To get the time constant, the voltage at the 680Ω resistor will be monitored by the analog
comparator. If the voltage drop at the 680Ω resistor is higher than the voltage of the internal
reference, this event will be notified to the 16-bit counter, which is started at the same time of
switching current on. The counter will save the state of this event. If the counter will overrun, this
will be counted by the program. After the event, the counter will be stopped by the program and the total time will be build with the saved counter stage and the overflow counter. The positive side
of the coil will be switched from VCC to GND and hold in this stage until monitoring of the voltages
of both pins shows, that no current is detected. The figure 5.62 shown a simplified diagram of the
measurement situation.
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Post by antigua on Dec 24, 2017 4:50:34 GMT -5
Here's the chapter of the manual on inductance measurement. 8MHz? ouch 5.4
Measurement of inductance
The measurement of inductance values will be done as separate part with all found resistors with less than 2100Ω. The methode of measurement is based on the growing of current by formula L Il = Imax · (1 − exp −t ) after switching on the current. The time constant τ = R is proportional τ to the inductance L, but reverse proportional to the resistor R. The current can only measured indirectly with the potential drop of a resistor. Unfortunately the time constant will be reduced additionally by the relative high resistance 680Ω, for that the measurement of little inductance values is additionally made difficult with the 8MHz
clock. To get the time constant, the voltage at the 680Ω resistor will be monitored by the analog comparator. If the voltage drop at the 680Ω resistor is higher than the voltage of the internal reference, this event will be notified to the 16-bit counter, which is started at the same time of switching current on. The counter will save the state of this event. If the counter will overrun, this will be counted by the program. After the event, the counter will be stopped by the program and the total time will be build with the saved counter stage and the overflow counter. The positive side of the coil will be switched from VCC to GND and hold in this stage until monitoring of the voltages of both pins shows, that no current is detected. The figure 5.62 shown a simplified diagram of the measurement situation. I don't think the actual test frequency would be 8MHz, as that would exceed the resonant peak of many inductors. |
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dazz
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Post by dazz on Dec 24, 2017 5:00:57 GMT -5
Here's the chapter of the manual on inductance measurement. 8MHz? ouch 5.4
Measurement of inductance
The measurement of inductance values will be done as separate part with all found resistors with less than 2100Ω. The methode of measurement is based on the growing of current by formula L Il = Imax · (1 − exp −t ) after switching on the current. The time constant τ = R is proportional τ to the inductance L, but reverse proportional to the resistor R. The current can only measured indirectly with the potential drop of a resistor. Unfortunately the time constant will be reduced additionally by the relative high resistance 680Ω, for that the measurement of little inductance values is additionally made difficult with the 8MHz
clock. To get the time constant, the voltage at the 680Ω resistor will be monitored by the analog comparator. If the voltage drop at the 680Ω resistor is higher than the voltage of the internal reference, this event will be notified to the 16-bit counter, which is started at the same time of switching current on. The counter will save the state of this event. If the counter will overrun, this will be counted by the program. After the event, the counter will be stopped by the program and the total time will be build with the saved counter stage and the overflow counter. The positive side of the coil will be switched from VCC to GND and hold in this stage until monitoring of the voltages of both pins shows, that no current is detected. The figure 5.62 shown a simplified diagram of the measurement situation. I don't think the actual test frequency would be 8MHz, as that would exceed the resonant peak of many inductors. No idea what I'm doing TBH, LOL Here's what seems to be the source code for inductance measurement www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/ReadInductance.c?revision=712&view=markup#l29Comment on line 106 reads "//start counter 1MHz or 8MHz" Also, according to the manual resistance must be lower than 2100 ohms to measure inductance, so we may be out of luck? |
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dazz
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Post by dazz on Dec 24, 2017 5:11:44 GMT -5
Oh, look what's there in page 47 of the manual...
3.10
Measurement of coils
The normal measurement of the inductance is based on the measurement of the time constant of the
current grow. The detection limit is about 0.01mH, if the resistance of the coil is below 24Ω. For
bigger resistance values the resolution is only 0.1mH. If the resistance is above 2.1kΩ, this technique
can never be used to detect coils. The measurement results of this normal measurement is shown in
the second line (resistance and inductance). With the samplingADC method a resonant frequency
of coils can be detected with greater inductance values. If this effect is noticeable, the frequency and
the quality factor Q of the coil is shown additionally in line 3.
The method of resonant frequency measurement can also be used for the determination of the
inductance value, if a sufficient big capacitor mith know capacity value is connected parallel to a little
inductance (<2mH). With a parallel connected capacitor the normal measurement of inductance
can no more operate well. If the resonant frequency let assume a parallel connected capacitor, the
inductance of the normal measurement is not shown and the resistance value is shown in line 1. For
this resonant circuit the quality factor Q is also computed and shown behind the frequency value in
line 3. You can identify this type of measurement with the inductance value at the first position of
line 2, followed by the text ” if ” and the value of the assumed parallel capacity. The value of this
3 10 − 30nF (L)).
parallel capacitor can currently only be set with the calibration function (1
For displays with only two lines, the content for the third line is shown time-delayed in line 2.
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Post by ms on Dec 24, 2017 7:55:08 GMT -5
Better check it against an Extrech. Pickup coils are low Q inductors (high resistance) with a considerable amount of capacitance. I did not find anything in the manual that says it is accurate in these conditions, but it might be.
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dazz
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Post by dazz on Dec 24, 2017 8:14:16 GMT -5
Better check it against an Extrech. Pickup coils are low Q inductors (high resistance) with a considerable amount of capacitance. I did not find anything in the manual that says it is accurate in these conditions, but it might be. Yeah, one of the guys at eevblog just confirmed it won't even try to measure H for high resistance (over 2KR) inductors sorry everyone |
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Post by antigua on Dec 24, 2017 15:01:54 GMT -5
I ordered one, I think it's a good purchase even if it doesn't work as hoped. I'll compare it to the Extech measures if it works at all.
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dazz
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Post by dazz on Dec 24, 2017 15:50:31 GMT -5
I ordered one, I think it's a good purchase even if it doesn't work as hoped. I'll compare it to the Extech measures if it works at all. Thanks so much antigua. Excuse my ignorance, I guess it's silly to even ask this, but what if we tried with a resistor in parallel to get it to fall below 2K ohms? would there be a way to calculate the inductance of the coil (pickup) on it's own? Another thing I'm thinking of, what if we "cheated" and changed the threshold value of 2100 ohms to something much higher, compiled and flashed the firmware? |
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Post by antigua on Dec 24, 2017 16:54:25 GMT -5
I ordered one, I think it's a good purchase even if it doesn't work as hoped. I'll compare it to the Extech measures if it works at all. Thanks so much antigua. Excuse my ignorance, I guess it's silly to even ask this, but what if we tried with a resistor in parallel to get it to fall below 2K ohms? would there be a way to calculate the inductance of the coil (pickup) on it's own? Another thing I'm thinking of, what if we "cheated" and changed the threshold value of 2100 ohms to something much higher, compiled and flashed the firmware? I don't know much about how it works, but I'd assume the limitations are not arbitrary. I'd guess that with a series resistance greater than 2k, the Q factor will drop below a point that the instrument relies upon in order to calculate the inductance. Guitar pickup coils are high inductance / high loss (eddy currents and series resistance) inductors by the standards of most inductors used in electronics applications, which is why you usually have to shell out for an expensive LCR meter. There's a discussion about it here music-electronics-forum.com/t39550/ , with a familiar name in the conversation. |
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Post by Deleted on Dec 25, 2017 3:01:55 GMT -5
The other nice thing is that this set is spaced 52mm end to end, for all three, which is essentially Fender standard, so you won't have trouble swapping cover colors. Some Chinese Strat sets, like the Donlis DS51 have 50/51/52 pole spacing, and so it's much more of a task to find alternate different covers for them. From what I gather, even in the most american-est/fender-est strat with 43mm nut and 56mm bridge, still a 52mm neck pup will be off at least for high/low E. I think the correct spacing for the standard spec'd strat would be smth like 54-51-50, given the bridge's angle. For asian spec'd strats it should be smth like 52-50-48, giving some rough estimations. |
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Post by ms on Dec 25, 2017 5:25:30 GMT -5
Thanks so much antigua. Excuse my ignorance, I guess it's silly to even ask this, but what if we tried with a resistor in parallel to get it to fall below 2K ohms? would there be a way to calculate the inductance of the coil (pickup) on it's own? Another thing I'm thinking of, what if we "cheated" and changed the threshold value of 2100 ohms to something much higher, compiled and flashed the firmware? I don't know much about how it works, but I'd assume the limitations are not arbitrary. I'd guess that with a series resistance greater than 2k, the Q factor will drop below a point that the instrument relies upon in order to calculate the inductance. Guitar pickup coils are high inductance / high loss (eddy currents and series resistance) inductors by the standards of most inductors used in electronics applications, which is why you usually have to shell out for an expensive LCR meter. There's a discussion about it here music-electronics-forum.com/t39550/ , with a familiar name in the conversation. That might trigger it to make a measurement, but it would have no way of getting the correct answer. |
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Post by antigua on Dec 25, 2017 13:15:24 GMT -5
The other nice thing is that this set is spaced 52mm end to end, for all three, which is essentially Fender standard, so you won't have trouble swapping cover colors. Some Chinese Strat sets, like the Donlis DS51 have 50/51/52 pole spacing, and so it's much more of a task to find alternate different covers for them. From what I gather, even in the most american-est/fender-est strat with 43mm nut and 56mm bridge, still a 52mm neck pup will be off at least for high/low E. I think the correct spacing for the standard spec'd strat would be smth like 54-51-50, given the bridge's angle. For asian spec'd strats it should be smth like 52-50-48, giving some rough estimations. That might be true, but in this context I'm just referring to the ease of replacing the plastic covers with a color other than the color they come with stock. 90% of the time I don't have to worry about cover color because it's so easy to replace, but you buy a set with this particular spacing and suddenly you're in a jam. |
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dazz
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Post by dazz on Dec 25, 2017 18:15:39 GMT -5
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Post by Deleted on Dec 26, 2017 2:51:06 GMT -5
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Post by antigua on Dec 26, 2017 4:28:08 GMT -5
I appreciate your looking into this. Making pickup analysis cheap and affordable is a game changer. In addition the the test frequency issue, another important aspect of the Extech is that you can select series/parallel resistance mode, and it seems to be important that it be in "series resistance" mode in order to give back a good result. The inductor / pickup has a high series resistance due to the thousands of turns of fine wire. I'm not sure what inductors out there would have a "parallel" resistance, I'm at a loss there. |
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Post by antigua on Dec 26, 2017 4:47:58 GMT -5
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Post by ms on Dec 26, 2017 6:24:53 GMT -5
I appreciate your looking into this. Making pickup analysis cheap and affordable is a game changer. In addition the the test frequency issue, another important aspect of the Extech is that you can select series/parallel resistance mode, and it seems to be important that it be in "series resistance" mode in order to give back a good result. The inductor / pickup has a high series resistance due to the thousands of turns of fine wire. I'm not sure what inductors out there would have a "parallel" resistance, I'm at a loss there. The Extech allows you to select series/parallel because it can. The instrument measures the ratio of voltage to current, which gives two numbers, amplitude and phase, or real and imaginary if you like complex numbers expressed in rectangular form. The instrument interprets those two numbers based on information from the user. If you choose "inductor", then you get to specify additional information describing how the instrument interprets the loss it measures. |
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Post by reTrEaD on Dec 26, 2017 8:46:22 GMT -5
Have you ever used something with that sort of layout? Looks like it would be particularly clumsy. |
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dazz
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Post by dazz on Dec 26, 2017 12:17:48 GMT -5
40 bucks for shipping those tweezers to Europe though  I wonder how the chinese manage to sell $1 items free shipping worldwide and still make some profit, but I digress |
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