Ferrite In Line Filter

[solmer]

Hi, I've seen this little gadget while surfing on EBay.....


http://cgi.ebay.com/Fisher-Whites-Minelab-Tesoro-Garrett-Coil-Inline-Filter-/250694315478?pt=LH_DefaultDomain_0&hash=item3a5e8badd6

What do you think about it? Any experiences? As far I know Minelab Expl. has an internal ferrite filter already, I checked it a few years ago while doing a small repair on my unit....

Good Luck and happy finds !!!!!

 

[kered]

I think i read something in the PI forum, made no difference what so ever

 

[Gib]

I tried it on a couple of Tesoro's. I couldn't max out sensitivity on either of them inside, so I gave it a shot. No effect what so ever. What kills me is I saw one of those end at $14.xx and another $2 shipping. You can buy a pack of two at Radio Shack for $3.

 

[Sven]

I did a post about these somewhere, don't recall.
They have absolutely no effect on a detectors performance
and they do nothing for the detector.
Here's info in layman's terms:
http://computer.howstuffworks.com/question352.htm

Bet you the detector manufacturers are shaking their heads at this seller.
Nice con job.......................

 

[Jeff In North Georgia]

Minelab was using them on their large 15" X 12" coils for the GP and SD series detectors.
My Minelab Explorer II has one inside the control head that the coil wires pass through. Not sure if other brands or their models use these?

Jeff

 

[Sven]

Sorry Jeff, need to see exactly what your talking about, don't think what your selling on ebay is the same as whats
"inside" the Explorer or GP? Supply a picture. Time to supply the proof that they work on the metal detectors you claim. How about
someone call the manufacturers master techs and get back to us?
Are not searchcoil wires "shielded" ?

http://homepages.tesco.net/~a.wadsworth/inductors.htm
http://www.darkwire.com.au/html/using_ferrite_chokes.html

"Those are ferrite beads. They act as low pass filters in that they help prevent higher frequency signals present in the wires from getting past the bead. However, these things are designed to filter out much higher frequencies than the ones causing EMI from "high wires" (ie. overhead power lines)."

http://www.antennex.com/shack/Dec99/beads.htm

 

[khouse]

For what they cost - If they worked that good the manufacturers would put them on.

 

[Sven]

I made an inquiry, here's the response.
Then you decide if you want to try one.

Okay Sven, I thought you were speaking of tuned inductors inside a metal detector, or the tuned cap/resistor inside the coil, but what you are speaking about, as a gimmick, is indeed a gimmick, a bull shit gimmick. They have had these out there for a long time, they are useles, do not work!!!

It is baloney, they do not know just what frequencies are out in the air, that could influence your metal detector, so they cannot work. It is some way to get money from you. They cannot possibly increase the efficiency of your metal detector. It is a BIG JOKE!!!


It is just like the units they attach to a digital cable system, and tell you you can subscribe to Pay Per View movies, and watch them to your hearts content, and the reporting from the digital cable box, back to the local cable system will not happen, and you will not have to pay for the movies! It is a screw job!

 

[kered]

Bet some have fallen for it though

 

[23950522]

Hi, I've seen this little gadget while surfing on EBay.....


http://cgi.ebay.com/Fisher-Whites-Minelab-Tesoro-Garrett-Coil-Inline-Filter-/250694315478?pt=LH_DefaultDomain_0&hash=item3a5e8badd6

What do you think about it? Any experiences? As far I know Minelab Expl. has an internal ferrite filter already, I checked it a few years ago while doing a small repair on my unit....

Good Luck and happy finds !!!!!

I could not get my head around why this guy was selling these ferrite snap on filters for metal detectors , they only cost pennies anyway! . I am a Ham and have been 20 years , we use ferrite beads / rings/ to reduce TVI and other problems regarding transmitting , what does a metal detector do?? transmits and receives its own electromagnetic signals ,well you knew that anyway, so would a ferrite filter help a detecterists .
For Mr Joe Bloggs average detectors on the beach or coin or artifact hunting the answer is !! NO but if your in the middle of the Australian out back looking for gold nuggets the answer would be yes , the interference would be from highly magnetic areas ,hot rocks ,etc where general interference is minimal and where , little or no discrimination is used they could be help full .

 

[khouse]

When I used to be an auto mechanic some thought wooden clothes pins were a solution to vapor lock. We would open the hood on some cars and trucks and see clothes pins snapped to the fuel lines. We just laughed and left them on. Some customers claimed better gas mileage, more horse power and of course no more vapor lock. I guess we should have told them the clothes pins didn't work and for $29.95 our ferrite filters are way better! All I can say is if you want to see how a ferrite filter is going to work on your detector - first try clothes pins.

 

[salmonriverhotrock]

I'm no expert on this stuff and was some years ago but I once read where a fellow was concerned about how people wrap their search coil wire up around the metal detector stem up to the control box. I seem to recall there was some thought it could have a negative effect on a metal detectors performance. At Very Low Frequincy, I'm not sure I can see any harm in it but besides the Ferrit filter or choke issue, maybe a Tech. out there can shed light on the wrapping of search coil wire around the stem. I know in the HF TX/RX radio world, to loop or coil coax wire can create a choke.

 

[JeffNS]

Just a personal observation...

I'm not about to argue the science of why using a Ferrite Choke will or won't work but I can attest to the fact that a friend was having problems hunting an area using his F5 due to what appeared to be EMI. The following day I brought a ferrite choke with me and he snapped it on his coil cable just ahead of the housing and the EMI dissappeared. He immediately removed it and EMI began wreaking havoc on his F5 again. We repeated this several times and there was absolutely no question that the ferrite choke made a significant difference. No choke and his F5 chattered like a chipmunk on crack....with choke...nice and quiet. No joke.

 

[stasys]

I cant say about what is on bay, but in explorer xs and i suspect others explorers you have two, one on coil connection cable from control panel and another on wires inside control panel.

 

[plugger]

He was able to use his WOT for the first time at this beach and I am looking forward to getting down there too in the near future. I couldn't use my S-8 there in the past and I want to see if it will make a difference now. They're cheap enough to put on all my coils and they don't hurt anything.

Plugger

 

[megadivers]

It looks like Fisher is using them now as well. The latest edition of the Gold Bug Pro uses ferrite beads on the coil wires inside the housing. If manufacturers are using them, they surely couldn't hurt.....

 

[GONGA]

I got 3 of these ferrite beads out of a plasma tv that wasnt working anymore and they cost me nothing (if they work on tv's then why wouldnt they work on detectors) .Any way I put one near the coil , 1 on the cable halfway along the shaft ,and 1 right at the end of the coil cable where it connects into the box...and it does seem to make the machine a little less chattery ,I own a whites DF and I can turn up the gain a little bit more.Anyway maybe it seems that way to me but I will leave them on coz they dont get in the way of anything.

 

[Ism]

They work in the control box because the wires aren't shielded. I imagine the control boxes are plastic on the units that have them. The cable from your coil to the control box should be shielded and therefore the ferrite beads have little effect.

 

[GoGoGopher]

A ferrite bead does nothing if a wire simply passes through it...the wire must be coiled around it to work...At least this is what I have been told...

HH,

 

[otlew]

Overview

Ferrite beads are used (in a way similar to inductors) as a passive low-pass filter. The geometry and electromagnetic properties of coiled wire over the ferrite bead result in a high resistive impedance (resistance) for high-frequency signals, attenuating high frequency EMI/RFI electronic noise. The energy is either reflected back up the cable, or absorbed resistively within the ferrite core and dissipated as heat. Only in extreme cases will the heat be noticeable.

A pure inductor does not dissipate energy; it merely absorbs energy from the circuit and returns it at a later time. A ferrite bead, by design, filters out the high frequency noise in the circuit by dissipating it as heat. The ferrite bead is effectively an inductor with a very small Q factor. When electrical noise within the target frequency range travels in the signal cable a back-emf is induced in the ferrite bead because of its high inductance. The material used to construct the ferrite bead however, becomes highly resistive at the design frequency range (the magnetic field within the bead is unable to establish properly at that specific frequency range) and the induced current inside the bead is dissipated as heat instead of inducing an opposing current back in the signal cable. It is for this reason that the specific circuit characteristics as well as the frequency band of the noise need to be taken into account when the ferrite bead is installed as a noise filter.

Ferrite beads are one of the simplest and least expensive types of interference filters to install on preexisting electronic cabling. For a simple ferrite ring, the wire is simply wrapped around the core through the center typically 5 or 7 times. Clamp-on cores are also available, which can be attached without wrapping the wire at all. Although the wire is not coiled around the core for this type of ferrite beads, the introduction of the ferrite core around the wire increases the self-inductance of the wire thus still has the effect of absorbing energy from the noise traveling in the wire. If the fit isn't snug enough, the core can be secured with cable ties, or if the center is large enough, have the cabling looped through one or more times.