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Thread: Spin Doctor type gauss meters?

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    Quote Originally Posted by SirPrimalform View Post
    I sent you a PM, but it hasn't shown up in my "sent" folder, so let me know if you didn't get it.
    I've got it (even twice). It's funny that you can send a message but cannot see it once it's sent. For me it's a bug. Let's hope that with 7 messages you can do a lot more now .

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    I think there may be a spot in the user settings where you have to turn on "save copy of sent messages" ?

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    Quote Originally Posted by g1 View Post
    I think there may be a spot in the user settings where you have to turn on "save copy of sent messages" ?
    Exactly, the PM/reply doesn't show in the "Sent Items" folder by default. One has to check the general settings below the message window before sending off.

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    Quote Originally Posted by MarkusBass View Post
    At the moment I have 2 prototypes but only one of them is for sale. But if there is a bigger interest I can make some more.
    It looks like this:
    Attachment 52136
    I still plan to redesign the front sticker to look more professional.

    Measurement of a Celestion speaker in Marshall JCM900:
    Attachment 52137
    Just a general remark (without knowing your meter): As flux density (B) may vary strongly with position and typical Hall elements are very small, the exact position of the sensor within the probe tip is critical. For this reason I prefer small and flat probe heads with specified sensor depth and location.

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    Quote Originally Posted by g1 View Post
    I think there may be a spot in the user settings where you have to turn on "save copy of sent messages" ?
    You are right: there is an option "Save a copy of sent messages in my Sent Items folder by default" in the User Profile. I thought that it is set to true by default but maybe it's not.

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    Last edited by MarkusBass; 01-25-2019 at 10:13 PM.

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    Quote Originally Posted by Helmholtz View Post
    Just a general remark (without knowing your meter): As flux density (B) may vary strongly with position and typical Hall elements are very small, the exact position of the sensor within the probe tip is critical. For this reason I prefer small and flat probe heads with specified sensor depth and location.
    In the final version of the meter there will be a fiducial on the top layer of the PC board. In the prototype I plan to mark it with a nail lacquer . Do you suggest that the tip of the meter should be thinner? I still can change it.
    Currently it looks like this:
    Click image for larger version. 

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    You can see that I can solder both the SMD or through-hole Hall sensor and there is a fiducial marking the exact position of the sensor.

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    Do you suggest that the tip of the meter should be thinner?
    A difference of 0.5mm in distance between Hall element and the magnet pole surface can change the result by 10%.

    The probe tip of my AlphaLab magnetometer measures 4mm (width) by 1.3mm (thickness).

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    Quote Originally Posted by Helmholtz View Post
    A difference of 0.5mm in distance between Hall element and the magnet pole surface can change the result by 10%.
    The probe tip of my AlphaLab magnetometer measures 4mm (width) by 1.3mm (thickness).
    I'm not sure what you mean by 1.3mm thickness of the probe tip. In my meter the Hall sensor is assembled on the bottom layer of the board and when doing the measurement it touches directly the magnet. There is no PC board in between. The thickness of the PC board is 1.75mm but since the magnet touches directly the sensor it is not important. I've seen some magnetometers with very narrow probe but I'm afraid that they are prone to break. So there should be a balance between the width of the probe and the risk to break it. I decided to make it wider just to avoid breaking it.

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    In my meter the Hall sensor is assembled on the bottom layer of the board and when doing the measurement it touches directly the magnet.
    So the probe has a defined measuring orientation (not intended for probe reversal) and it's only the depth of the hall chip inside the sensor housing that determines the minimum measuring distance.

    I decided to make it wider just to avoid breaking it.
    As long as the probe width allows flat placement on staggered strat PU poles, it's probably fine with most PU applications.

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    Quote Originally Posted by Helmholtz View Post
    So the probe has a defined measuring orientation (not intended for probe reversal) and it's only the depth of the hall chip inside the sensor housing that determines the minimum measuring distance.
    Of course. The meter displays the orientation of the magnet that is measured (letters N/S) so there is only one way to make the measurement. You cannot reverse the probe and expect that correct polarity of the magnet is displayed.
    Quote Originally Posted by Helmholtz View Post
    As long as the probe width allows flat placement on staggered strat PU poles, it's probably fine with most PU applications.
    Good point. I'll think about it. Thanks for pointing this out.

    Mark

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    Quote Originally Posted by Helmholtz View Post
    As long as the probe width allows flat placement on staggered strat PU poles, it's probably fine with most PU applications.
    Will this shape be better?
    Click image for larger version. 

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    This is bottom layer as seen from the bottom.

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    Quote Originally Posted by MarkusBass View Post
    Will this shape be better?
    Click image for larger version. 

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    This is bottom layer as seen from the bottom.
    Looks better to me. What are actual dimensions?

    The SpinDoctor has a tip width of 5.4mm measured at the sleeve and I got used to it. But for most applications a width of up to 0.5 inch (12.7mm) should be OK.

    Other opinions?

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    Quote Originally Posted by Helmholtz View Post
    Looks better to me. What are actual dimensions?
    The tip is 5 mm wide.The lower part is 14 mm wide but this shouldn't be critical.

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    Guass meter question

    Hi Markus
    The Elepro meter that I put together has 2 hall effect sensors on opposite sides of the circuit board. It works fine for most measuring purposes (a little thick for under string measurement, but I dont do that anyway as the strings affect the readings) I used epoxy around the sensor to protect it but the face of the sensor is open Click image for larger version. 

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    I Have attached a photo of one side. Let me know when or if you are selling some meters and i'll have one.
    Cheers
    Andrew

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    Yes, I'll be selling them. But at the moment I have just 1 prototype that I can sell (the other one will be used for tests) and I ordered several PC boards yesterday. I think I'll get them in a week. So in let's say 2 weeks I'll have some more meters.

    Mark

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    Hi Mark

    Thanks, there`s no rush.

    Andrew

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    Yesterday I visited friends in Milan (IT) who make their own pickups and guitars and I tested my meter with one of their pickups (with alnico magnets). I was a little afraid that the magnets are to strong for my meter. The maximum value that can be measured is 1640 Gs and their magnets are 1129 Gs. It was close but there is still some headroom . Are there pickups with even stronger magnets?

    Click image for larger version. 

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    Quote Originally Posted by MarkusBass View Post
    Yesterday I visited friends in Milan (IT) who make their own pickups and guitars and I tested my meter with one of their pickups (with alnico magnets). I was a little afraid that the magnets are to strong for my meter. The maximum value that can be measured is 1640 Gs and their magnets are 1129 Gs. It was close but there is still some headroom . Are there pickups with even stronger magnets?

    Click image for larger version. 

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    Hi Mark

    If the sensors only go to 1640 g maybe you can use the same ones that elepro used
    https://music-electronics-forum.com/...ro+gauss+meter

    Features:
    Range +/- 5375 gauss (with AD22151 sensor) or +/- 1650 Gauss (with A1302 sensor)
    Normal, peak-hold and average mode
    1024 sample per reading in normal mode, 64 in hold peak and 131k in average mode
    On board tactile push buttons to reduce cost and wiring
    Two sensor (double face) probe with storable calibration (sensivity value from 0.250 to 6.000 mV/gauss) and polarity for each one
    Auto zero set at start-up and at sensor change... + zero set button
    Lcd backlight button


    Check the link above. I hope it helps
    Cheers
    Andrew

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  19. #54
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    Here's the link to the elepro attachment that lists the various sensors.
    https://music-electronics-forum.com/...4&d=1513847570
    T

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    Quote Originally Posted by MarkusBass View Post
    Yesterday I visited friends in Milan (IT) who make their own pickups and guitars and I tested my meter with one of their pickups (with alnico magnets). I was a little afraid that the magnets are to strong for my meter. The maximum value that can be measured is 1640 Gs and their magnets are 1129 Gs. It was close but there is still some headroom . Are there pickups with even stronger magnets?

    Click image for larger version. 

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    To me the range up to 1640G would be fine. My spin doctor has a range of 1700G and it works with all PU measurements. I chose the lower range version, as it provides better resolution at lower fields.
    The range would be to low for direct measurements at stronger ceramic and neo magnet pole faces. But what matters to the strings is the field strength at the top of the PU poles.

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    I agree with Helmholtz that there is no need to change the sensor. It would mean loosing precision of the measurements. However, if there is a demand to do it, I can easily change the range of the meter either to 3280, or 6560, or even to 13120 simply by changing the Hall sensor (to a different type than AD22151) and changing one constant in the program. But changing the sensor to AD22151 would require a redesign of the PC board and most probably big changes in the program (which I want to avoid).

    Mark

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    Here's some readings of bar magnets.
    https://music-electronics-forum.com/...gauss+readings
    Your limits should be fine, unless you get into measuring some NEOs.
    Some A5 rod magnets will measure way over 1000, at full charge.
    If you do a search on gauss readings, there are lots of other threads out there on the subject.
    GL,
    T

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    Thanks,

    It looks like there may be problems with A9 magnet. But in this case I may change the Hall sensor and get the range up to 3280 (with slightly lower precision).
    The pickups that I tested until now were in a range of 500-700 Gs.

    Mark

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    This is the latest version of the meter (next to the prototype). I still have to buy the OLED display and program the meter (with the latest version of the software). It will take about two weeks to do.

    Click image for larger version. 

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    Quote Originally Posted by MarkusBass View Post
    This is the latest version of the meter (next to the prototype). I still have to buy the OLED display and program the meter (with the latest version of the software). It will take about two weeks to do.

    Click image for larger version. 

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    Looking good especially with new narrower tip.
    I have a Spin Doctor ER which will measure powerful N52 neo's no problem, but an accurate reading up to say 3000G would be fine for pickup work.
    Please let me know when you are in production after prototyping as I would like a backup for my Spin Doctor.
    Thanks!

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    I have the normal one and was about to buy the ER version then I found out he stop making them. Its really unfortunate. Any other similar gauss meters out there?

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    Does ER means "extended range"? The meter I designed can measure values up to 1690 Gs. I was wrong thinking that it can be easily modified by replacing the Hall sensor. The only sensor that I found out for the extended range is AD22151, which is in a different package than I used. So I would need to redesign the PC board. Have you got the schematic of your meter? I'm curious how the gain if the Hall sensor was switched. With MOSFET transistors or in some other way?

    PS1: the value 1690 Gs seems to cover most of the pickup types I have seen (the highest value I measured was 1100 Gs). What type of pickups require extended range? Or you want to measure neodymium magnets?

    PS2: is neodymium N52 used for guitar pickups?

    Mark

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    Hey Mark,

    yea ER means extended range. http://gravitastech.weebly.com/spin-doctor-er.html

    I was looking to get the ER version because I mixed up a bunch on neodymium magnets and I need to know their gauss value.

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    Thanks for the info. So the ER version had a fixed range 25000 Gs. It's suitable for neodymium magnets but for pickups you loose accuracy. This can be done but requires a redesign of the PC board.

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    If you just need to select/compare strong neos, you can do this with the lower range meter at a fixed distance (using a spacer) from the pole face. The flux density (B) drops rapidly with distance.

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    Quote Originally Posted by MarkusBass View Post
    Thanks for the info. So the ER version had a fixed range 25000 Gs. It's suitable for neodymium magnets but for pickups you loose accuracy. This can be done but requires a redesign of the PC board.
    The v. 1.1 looks pretty good. I only need to measure alnico bars, so no need for extended range for me. Let me know when you're open for business.

    Yours very truly,

    Pepe
    Milano, Italy

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    Pepe aka Lt. Kojak
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    Quote Originally Posted by LtKojak View Post
    The v. 1.1 looks pretty good. I only need to measure alnico bars, so no need for extended range for me. Let me know when you're open for business.
    Pepe
    Milano, Italy
    Ciao Pepe,

    It's a pity that we couldn't meet in Milan.
    Have you seen this photo?
    Click image for larger version. 

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    It was made in Milan - pickups with alnico magnets. I was wondering whether these were your pickups.

    Mark

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    Quote Originally Posted by MarkusBass View Post
    Ciao Pepe,

    It's a pity that we couldn't meet in Milan.
    Have you seen this photo?
    Click image for larger version. 

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    It was made in Milan - pickups with alnico magnets. I was wondering whether these were your pickups.

    Mark
    I do not wind p'ups for a living, Markus.

    Having said that, I've been known for modding, repairing and re-winding a fair amount here and there, then and now...

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    Pepe aka Lt. Kojak
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    Finally I have 7 meters ready. One of them has black enclosure. I have also 2 prototypes but I need to update their software - there are minor differences between the prototypes and the final version. I think I need two weeks to do it and they will be also available (and they will be cheaper). The main difference between the prototype and the final version is the tip of the meter (this can be corrected with a dremel tool) and lack of the charging status LED. The rest will work in exactly the same way.

    Click image for larger version. 

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    Quote Originally Posted by MarkusBass View Post
    Finally I have 7 meters ready. One of them has black enclosure. I have also 2 prototypes but I need to update their software - there are minor differences between the prototypes and the final version. I think I need two weeks to do it and they will be also available (and they will be cheaper). The main difference between the prototype and the final version is the tip of the meter (this can be corrected with a dremel tool) and lack of the charging status LED. The rest will work in exactly the same way.

    Click image for larger version. 

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    Great job! They look awesome. Do you think you could make a little You Tube video of one in action, showing the various functions? That would be really helpful!

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