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Thread: Possible Fix for EMI

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  1. #1
    Charter Member
    us
    Aug 2014
    Laconia, NH
    Currently: XP Deus v4.1 Minelab Equinox 800 Fisher Gold Bug 2 Previously: Garrett GTA 500 Garrett Ultra GTA 1000 Garrett GTAx 1250
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    823 times
    All Types Of Treasure Hunting

    Possible Fix for EMI

    Hey guys,

    I was on another forum a second ago, reading up on the Fisher Gold Bug 2, and I came across someone who was experiencing the effects of EMI on his machine.

    Well, another fella chimed in and claimed that he had basically EMI-proofed his machine by attaching one of these little ferrite chokes to the cable, just before it enters the control unit. The photo below shows a ferrite choke. It's a little snap-on device that kills electromagnetic interference and can be purchased on Amazon very inexpensively.

    Well this got me to thinking... if it would work on the Gold Bug 2, then there's no reason why it shouldn't work on the Equinox. So to test my theory, I'm about to buy a pack of these ferrite chokes from Amazon and test one out on my 800.

    So far, the only fix I've seen for this machine's erratic behavior has been to put your cell phone in airplane mode. But what if it's not your cell phone? What if it's power lines or some other source that's causing your machine to act up? That's why I want to test this out for myself.

    Anyone want to chime in with any questions or comments, please feel free. Maybe one of you have already done this with great success. Maybe one of you can tell me with certainty why this will or will not work.

    Anyway, I'm out for now. I'll post my findings here once I've reached a conclusion as to whether this will work or not.Click image for larger version. 

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    Slowtaknow and ltd063 like this.

  2. #2
    us
    May 2011
    1,271
    2527 times
    These have been talked about for years on the forums.
    The consensus is they won't really hurt anything but they also don't actually work when it comes to detectors.
    They are designed to filter out higher frequencies than our normal enemy, EMI that is emitted by high tension electric wires.
    Then again who knows, stranger things have happened.
    Report back for sure.
    "Artificial intelligence is no match for natural stupidity."

    Currently hunting with an F70, a Mojave and a borrowed Red Racer.
    Annnnd now an Equinox 800

  3. #3
    us
    Mar 2014
    Traveling US to work
    Current Whites DFX Past Garret GTI 2500 and others Prospecting Minelab GPZ 7000 Past SD 2100 GP 3000 (retired)
    1,902
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    Metal Detecting
    As digger27 says, cant hurt. I also agree that ferrite beads are intended for radio frequencies having used them in electronics myself. I suspect the emi interference from cell phones on the NOX is not due to the coil lead but internal to the control head. But I to will be interested to see what you come up with.
    laidback4sho likes this.
    Everyone Believes they have gold buried in the back yard... small wonder so few ever look for it.

  4. #4
    us
    Dec 2012
    Concrete, WA
    Nokta FoRs Gold, a Gold Cube, 2 Keene Sluices and Lord only knows how many pans....not to mention a load of other gear my wife still doesn't know about!
    3,105
    5096 times
    Prospecting
    Ferrite beads, or "chokes", as you call them, are designed to
    absorb the conducted emissions traveling up the exterior of the
    cable. If the cable itself is acting as an antenna, then the ferrite
    bead can attenuate those signals before they enter the device.

    If the input port where the cable connects to the device is
    not properly grounded, the conducted emissions can cause
    all manner of issues.

    https://en.wikipedia.org/wiki/Ferrite_bead
    laidback4sho likes this.
    Mike (aka Dizz)

    "If you love wealth better than liberty, the tranquillity of servitude better than the animating contest
    of freedom, go home from us in peace. We ask not your counsel nor your arms. Crouch down and lick
    the hands which feed you. May your chains set lightly upon you, and may posterity forget that you
    were our countrymen." ~~ Samuel Adams, 1776

    Dizzy's Super-Simple, Universal Rule of Forum Conduct: Don't be an ass.

  5. #5
    ca
    Dec 2015
    Whites xlt,ctx3030,equinox 850
    286
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    All Types Of Treasure Hunting
    could wrap the control box in tinfoil and have a chain draging on the ground....
    laidback4sho likes this.
    Reading a manual can make you look real smart
    Not reading a manual...can just make you look not so smart.
    Telling people you can't read on a forum....just makes you look stupid.

  6. #6
    Charter Member
    us
    Jul 2015
    Near Ground Zero for Insanity
    XP Deus with HF Coils and Mi6 Pinpointer/ML Equinox 600/800/ML GPX 4800/Garrett ATX/Fisher F75 DST/Tek Delta/Whites MXT/Garrett Carrot/Piranha Relic Shovel
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    I have not run into EMI that hasn't been addressed by:

    Keeping my phone away from the vicinity of the control head (I don't put it in airplane mode because I use it for site coverage tracking).

    Doing an auto, and if necessary, manual noise cancel. Must be done individually for each mode. Same for Ground Balance.

    Lowering sensitivity, as necessary. The machine is super hot, so lowering sensitivity 5 or so points does not kill depth that much, but there is a point where it starts to rapidly drop off. There may be a sweet spot between 15 to 20 on sense where you are actually increasing signal to noise ratio and relative depth performance, so don't be afraid to do this to combat EMI.

    If running in All Metal, ground feedback noise may appear to mimic EMI. If you are getting a lot of variable negative numbers then do a ground balance.

    Agree the ferrite beads will not hurt, but depending on the source of the EMI, they may not be effective either. Worth a shot.
    Last edited by vferrari; Jun 14, 2018 at 08:50 AM.
    laidback4sho likes this.
    "The future ain't what it used to be..."

  7. #7
    us
    Title? old fart

    Jun 2014
    mid western ARK
    XP Deus with 9"LF and 9" HF Coils and 600 Equinox
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    7523 times
    Metal Detecting
    Honorable Mentions (3)
    it would be cool if it does work. one of the things that I have learned in life, sometimes things work and work very well that weren't supposed to work and some didn't work at all that were supposed to work the best. kind of like an unrated team stomping a number 1 team, only one way to find out. sometimes the simplest fix works the best. Good luck
    laidback4sho likes this.
    LUKE 15 : 8 "OR WHAT WOMAN, IF SHE HAS TEN SILVER COINS AND LOSES ONE COIN,DOES NOT LIGHT A LAMP AND SWEEP THE HOUSE AND SEARCH CAREFULLY UNTIL SHE FINDS IT?" 15 : 9 "AND WHEN SHE HAS FOUND IT, SHE CALLS TOGETHER HER FRIENDS AND NEIGHBORS, SAYING, "REJOICE WITH ME, FOR I HAVE FOUND THE COIN WHICH I HAD LOST!"

  8. #8
    us
    Feb 2011
    Upstate NY
    Equinox 600, Teknetics Omega 8500, Garrett GTA-1000, Pro-Pointer
    66
    75 times
    Metal Detecting
    You will need to identify the offending frequencies and obtain the correct ferrite bead to suppress it. Best case it helps, worse-case, you've suppressed the signals going to and from your coil, which would not be good.
    laidback4sho likes this.
    Check out my other hobbies at www.dplivingston.com You'll be surprised!

  9. #9
    Charter Member
    us
    Rawhide

    Nov 2010
    SouthWestern USA
    Etrac, F75, AT Pro.
    3,427
    1926 times
    All Types Of Treasure Hunting
    EMI is the machines way of saying it is working. I would just hunt with it as long as there is no danger to the machine.

  10. #10
    Charter Member
    us
    Jul 2015
    Near Ground Zero for Insanity
    XP Deus with HF Coils and Mi6 Pinpointer/ML Equinox 600/800/ML GPX 4800/Garrett ATX/Fisher F75 DST/Tek Delta/Whites MXT/Garrett Carrot/Piranha Relic Shovel
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    Quote Originally Posted by Quisp View Post
    You will need to identify the offending frequencies and obtain the correct ferrite bead to suppress it. Best case it helps, worse-case, you've suppressed the signals going to and from your coil, which would not be good.
    The ferrite bead/choke should only suppress radio frequency level signals (above the ferrite bead cutoff frequency) that are trying to penetrate the coil cable shield from an external source or exit the coil cable through the shield, it should not affect signals travelling within the cable from the coil, therefore, it should not affect desirable signals to/from the coil to the control box and should not degrade detector performance. Again, the ferrite bead will only help if the source of the external interference is entering the control box via the cable acting as antenna and only interference that is above the cutoff frequency of the choke.
    Last edited by vferrari; Jun 14, 2018 at 04:54 PM.
    laidback4sho and johnwon2 like this.
    "The future ain't what it used to be..."

  11. #11
    ca
    Hawks88

    Aug 2012
    Niagara falls
    Equinox 600, fisher gold bug pro.
    3,130
    2334 times
    All Types Of Treasure Hunting
    Thanks for all that info.

  12. #12
    us
    Jan 2007
    Cape Cod, Massachuestts
    Garrett (Infinium, ATPro, ATX), Minelab Excalibur, Troy (X2 X5), Tesoro Conquistador, Whites (Surfmaster PI, Quantum), JW Fisher 8X, DetectorPro Underwater 8", Minelab Equinox 800, Pro-Find 35
    384
    413 times
    Beach and Shallow Water Hunting
    My camera will not download its pictures without the Ferrite Choke on the cable, as supplied by the manufacturer.

    The cause for the EMI on one PI detector I have was an extra ground lead on only one end of the cable. The fix was to un-solder the the ground lead, what a difference that made. The PI ran almost as smooth as my Excaliburs.
    vferrari and laidback4sho like this.

  13. #13
    us
    Feb 2011
    Upstate NY
    Equinox 600, Teknetics Omega 8500, Garrett GTA-1000, Pro-Pointer
    66
    75 times
    Metal Detecting
    Quote Originally Posted by vferrari View Post
    The ferrite bead/choke should only suppress radio frequency level signals (above the ferrite bead cutoff frequency) that are trying to penetrate the coil cable shield from an external source or exit the coil cable through the shield, it should not affect signals travelling within the cable from the coil, therefore, it should not affect desirable signals to/from the coil to the control box and should not degrade detector performance. Again, the ferrite bead will only help if the source of the external interference is entering the control box via the cable acting as antenna and only interference that is above the cutoff frequency of the choke.
    Ferrite beads are like a resistive load to high frequencies. If the cable shielding is allowing the unwanted frequencies to enter the cable, then the wanted "good" signals inside the cable could see a slight voltage drop if you choose the wrong ferrite value.


    Check out my other hobbies at www.dplivingston.com You'll be surprised!

  14. #14
    Charter Member
    us
    Jul 2015
    Near Ground Zero for Insanity
    XP Deus with HF Coils and Mi6 Pinpointer/ML Equinox 600/800/ML GPX 4800/Garrett ATX/Fisher F75 DST/Tek Delta/Whites MXT/Garrett Carrot/Piranha Relic Shovel
    2,929
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    All Types Of Treasure Hunting
    Quote Originally Posted by Quisp View Post
    Ferrite beads are like a resistive load to high frequencies. If the cable shielding is allowing the unwanted frequencies to enter the cable, then the wanted "good" signals inside the cable could see a slight voltage drop if you choose the wrong ferrite value.

    True regarding the ferrite beading actually "impeding" high frequency AC signals. But these are AC signals EXTERNAL to the cable that are coupled onto the shield acting like an antenna and feeding that RF energy into the control box via the shield pin connection. There is coupling between the shield and the signal on the inner conductor but there the shield acts as an attenuator to the conductor on any external voltage that coupled onto the shield. So say 5 volts AC of common mode rf noise is coupled onto the shield as external common mode EMI, the effect will be small (typically 1/100 or greater depending on the impedance of the coax and its own cutoff frequency). The ferrite bead merely lowers this external coupled voltage further if the source is high frequencies above the ferrite bead cutoff freqency. The cutoff frequency should only impact the effectiveness of the bead (depending on the frequency of the noise), but it still not have a significant if any effect on the conducted signal, but should only have no effect on the noise or make the situation better, but should not lower the conducted signal level between the coil and the control box as far as I can tell based on the fundamental circuit theory and some of the articles I have read.

    BTW - I did check out your website and it is fantastic. You have built some cool replicas and gadgets from some of my favorite classic films. Thanks for the link.
    Last edited by vferrari; Jun 15, 2018 at 04:38 PM.
    "The future ain't what it used to be..."

  15. #15
    us
    Rook

    Nov 2013
    Mississippi
    AT Pro, Fisher F75 Limited, White M6, XP Deus Lesche hand digger,Lesche Predator shovel.NEL Storm and Tornado coils.
    3,748
    2766 times
    All Types Of Treasure Hunting
    Let's say it did help(some). Where on the Deus where you attach it? As of now, I just reduce the Sens. or move away from power lines or whatever is causing the problem.
    Words not spoken never have to be defended

 

 
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