my detector coil crazy

[OhioDeb]

I have noticed my cheap little detector makes a beep like it found something when I occasionally tap the coil on the ground. Is this normal for detectors? OhioDeb

 

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[Sandman]

Yes it is normal....Years ago they would also sound off if they were rubbed on wet grass. You might also want to keep away from electrical wires, security fences and buried cables as these will set it off too.

 

[LuckyLarry]

NO Deb, but most likely it is because your cable isn't wound snugly around the search pole (shaft). This loose cable allows the search coil to detect the cable movement. Duck tape both ends to keep it snug around the shaft, but don't over-tighten or over-stress it.

If that doesn't help (and only in a worse case scenario) then your actual coil (wire) windings (may) have become dislodged inside the search coil. This usually happens if the thing is banged against rocks, etc..

A good tech or crafts-person can open the coil (VERY carefully) and re-glue the windings - if that's the problem - but a beginner shouldn't attempt it since the windings are impedance-balanced VERY precisely - and therefore very easily messed up. I have an old 12" search coil that I recently repaired with the same problem and now it works quite well. I've done several others too. It's very tricky and tough to cut the search coil open to re-attach it without cutting the winding wires. One good way to troubleshoot the detector first is to turn the detector on, then shake it hard enough to see (or hear) if the windings have become dislodged (loosened) inside. If so, the detector will likely make accompanying unaccounted-for audio sounds that indicate the loose winding. I used to repair metal detectors, and for a while I worked in R&D for one of the major metal detector manufacturers (brand name withheld), and for the Department of Defense in Electronics Engineering of the Mark48 Nuclear/Electronics Torpedo Guidance Systems. Oh, I forgot to mention, I have one just like yours and mine doesn't do that.

Let me know what you find out, and HH

LL, AKA "EasyMoney"

 

[Lowbatts]

Shaft wobble, coil connectors and the like can cause the frequent beep. Wind that cable around the shaft so it's fairly close to the shaft, but use some plain electrical tape if you can't find some god velcro connectors.

Don't use "duck tape" unless you know it's not aluminized or metallic in any way. Unless you want to detect tape on your shaft most of the time....

 

[Sandman]

Yeah Larry, your right. I was hasty in my answer and didn't think of the cable might be loose too.

 

[Woodland Detectors]

NO Deb, but most likely it is because your cable isn't wound snugly around the search pole (shaft). This loose cable allows the search coil to detect the cable movement. Duck tape both ends to keep it snug around the shaft, but don't over-tighten or over-stress it.

If that doesn't help (and only in a worse case scenario) then your actual coil (wire) windings (may) have become dislodged inside the search coil. This usually happens if the thing is banged against rocks, etc..

A good tech or crafts-person can open the coil (VERY carefully) and re-glue the windings - if that's the problem - but a beginner shouldn't attempt it since the windings are impedance-balanced VERY precisely - and therefore very easily messed up. I have an old 12" search coil that I recently repaired with the same problem and now it works quite well. I've done several others too. It's very tricky and tough to cut the search coil open to re-attach it without cutting the winding wires. One good way to troubleshoot the detector first is to turn the detector on, then shake it hard enough to see (or hear) if the windings have become dislodged (loosened) inside. If so, the detector will likely make accompanying unaccounted-for audio sounds that indicate the loose winding. I used to repair metal detectors, and for a while I worked in R&D for one of the major metal detector manufacturers (brand name withheld), and for the Department of Defense in Electronics Engineering of the Mark48 Nuclear/Electronics Torpedo Guidance Systems. Oh, I forgot to mention, I have one just like yours and mine doesn't do that.

Let me know what you find out, and HH

LL, AKA "EasyMoney"

 

[LuckyLarry]

Not a prob Dennis? (I forget names a lot more than I used to). It's easy to pass over the little things.

So have you heard of any new detectors coming out with newer technology? I read where there is a PI that finds a beer can at 5 feet, so claimed in their ad. $1500 isn't a bad price, but if they can get it down to coin-sized at 3' they will dominate the market.

http://biznetmall.com/frame-detector-pi/

Larry

 

[OhioDeb]

Thanks for the help. OhioDeb

 

[LuckyLarry]

Lowbatts, if the duck tape is snug there won't be any movement to disturb the field, even of it's made of pure copper. Here is an old trick you can use to reduce sensitivity, and it will explain why duck tape won't hurt if applied correctly:

Duck tape a steel washer the size of half dollar right on top of the search coil. Leave it there. Then turn your detector on. The steel washer will interrupt the signal (intensity) just like ground balance (AKA rough discrimination) or regular discrimination (AKA in the engineering field, fine ground balance), and the sensitivity will be reduced. If the washer and the duck tape do not move and stay right with the coil there will be no interference. With enough of a signal (like a 3" tin can lid) is taped to the top of the coil, the detector can have it's sensitivity and radiating power reduced so far that a coin can't be detected past 2", even in air. This is not a joke. Try different sizes of steel washers and experiment with the thing. People often did that way back in the 80's, especially with the old Fisher 400 series and Garrett Deepseekers, both with so much power that they had to sometimes be tamed a bit.

LL