EMI

[redmule]

How far from a electoral source do you have to be in order for your detector to no longer be effected by EMI and what can be done to your detector to eliminate interference from EMI.Thank you for your help.

 

[Dave J.]

two feet or 2,000 miles, depends on the source

http://www.fisherlab.com/hobby/davejohnson/Electrical%20Interference.htm

--Dave J.

 

[redmule]

Dave J. Thank you . That is just what the doctor ordered.

 

[c t]

Mr.Johnson. Thank you for the link it answers all the questions that I had re emi. Well done. Be well. C t

 

[bigtim1973]

You can buy an EMI filter to put on the cable of the coil. They are not much and are supposed to eliminate alot of the cycling sound interference. I have one comming today and will give an update this evening and I will let you guys know if it works good or not, Tim

 

[redmule]

Thank You Tim that would be great. Be sure to let us know were to get the filter and how much they cost.

 

[bigtim1973]

OK here it goes fellow detectorist!! I received my EMI filter today. I got it off of e bay and it cost me $4.95 plus like $2.00 bucks for shipping. You can find it by searching metal detector and EMI. I received it today and it is made by TDK. I know I used to see this stuff at radio shack during my tinkering days but when I pulled into radio shack today, they do not even carry them any more for CB cables like they once did. This one says it is 9MM diameter center and all it is, is a small ferrite filter which is basically either lead or a low strength magnet in a little plastic housing about 1" or so long and it clips over the coil cable wire as close to the detectors plug to the control box as you can get it. I noticed that Teknetics are now putting more shielding around the plug than the earlier model coil cables, so on mine there is about 2-3 inches of what looks to be shrink tubing coming out of the plug on the coil cable wire. So I placed it there about 1/8" at the end of the extra shielding on the coil cable. Also I have noticed the newer model coils shrink wrap actually begins over the plugs end and extends down onto the coil cable comming from the plug that screws into the housing. I believe First Texas are tinkering around with the best way. Upon taking it out to test it, I turned it on, then ground grabbed it and turned up the sensitivity knob to max. I went right under the electrical wire to my house and it performed much better. However when I lifted the coil off of the ground it immediately went to the EMI cycling sound. As long as I kept the coil on the ground sweeping it, it remained quiet. I really was about maxed out on my sensitivity too. So at the end of the driveway the power lines all meet at the corner of our property and splits off to all of the neighbors and such which are down the road. I was metal detecting a place recently with a similiar situation out of town and I had to turn down my sensitivity to around 50-55 or less to make it stop that cycling hummng sound near those set of power lines. Today at the end of our property I went directly under where all the electrical wires meet and I must say I had it about all the way clockwise it would go and had to turn it down just a bit to get away from false signals and it was much better as long as I kept the coil on the ground sweeping it like a normal coin hunting. Mind you, if there was a target there I wanted to dig, I would have to turn the sens. down while I was retrieving the target but other than that, then just turn it back up when I went to searching again. I believe that this little ferrite filter has done a pretty good job of knocking out that EMI while swinging the coil. Now I went and done another search on e bay and have seen a pack of like 50 of these things for 40 bucks from China, I might just go ahead soon and fork over the dough and buy a pile of these little ferrite filters to have on hand. If you guys do you detectors please keep me informed on the results, as I also would like to know how it does for you guys. HH, Tim .

 

[redmule]

Great follow up.Thank you Tim

 

[bigtim1973]

Great follow up.Thank you Tim

Your welcome, keep us posted, Tim