TESORO GOLDEN SABRE

[satdaveuk]

I have been running a thing stip of copper foil around the coil and then a layer of mylar conductive side inward. That way, I have something to solder to.

Sensitivity is noticably reduced using copper or aluminum foil tape. I first noticed this when I made a couple of HH coils. One with Mylar was more sensitive.

Now thats interesting because ive done the strip as you do in the past but not all the way around and ive done the twist but continued all the way around , so there is a difference.
Now the last question which is important when your wrapping the mylar sheild are you doing it in one continuious peace of mylar or a number of strips.
The mylar im using is very thin and easly snaps normaly happens when im near to the end.

Regards

[der_fisherman]

Now thats interesting because ive done the strip as you do in the past but not all the way around and ive done the twist but continued all the way around , so there is a difference.
Now the last question which is important when your wrapping the mylar sheild are you doing it in one continuious peace of mylar or a number of strips.
The mylar im using is very thin and easly snaps normaly happens when im near to the end.

Regards

I only use strips of cooking foil (next time a blanket!!), but what I do first is to first wrap the coil in very thin insulating tape, then I bind a stripped back piece of low voltage flex wiring, but leave a gap, then the short strips of foil, "just" overlapping so it is not too thick, same gap, then a thin insulating tape again (to stop shorts across the gaps of the F.Shield) as tight as possible. In fact all layers are as tight as possible with the coils super glued to make them stiff....

I then check continuity of the foil/Faraday shield carefully with a needle....

The next coil I make will have Mylar instead of foil........I am sure it will be much better.

I often wonder if the Faraday shield "gap" width makes a difference, perhaps Don B. could tell us what he uses?

regards

Andy

PS. I do not connect the dhield to either of the coil connections at the head, I feed a single ground wire from both shields to the electronics. I may run two grounds next time to see if it improves things, one per coil!!

[Lefizz]

I have no experience in coil building but has anyone tried using Teflon pressure tape between the coil and the shielding. Its very thin, strong and an almost perfect insulator. I would have though i would have worked better than insulating tape.

I may of course be completely wrong

[DIRCEU]

I have no experience in coil building but has anyone tried using Teflon pressure tape between the coil and the shielding. Its very thin, strong and an almost perfect insulator. I would have though i would have worked better than insulating tape.

I may of course be completely wrong

Hi!

you're right!

I wound my SURF'S COILS with a cotton layer and after several layers with Teflon tape and works great.

Now I can detect bricks, bottles, ceramic etc...He! He!

Best Regards

DIRCEU

[der_fisherman]

I have no experience in coil building but has anyone tried using Teflon pressure tape between the coil and the shielding. Its very thin, strong and an almost perfect insulator. I would have though i would have worked better than insulating tape.

I may of course be completely wrong

Its a good insulator, but not strong and you cannot rely on it potting as it does not stick to most glues and fillers...Non-Stick?
Regards
Andy

[dfbowers]

Hi Don

Could you explain what the problem is with copper tape as shielding material? Reduced sensitivity? Instability? I haven't used it but I would have expected it to be similar to aluminium foil (except that you can solder to it) which seems to be widely used.

Gwil

Copper tape works well so not really a "problem" so to speak. It's easy to apply and you can solder to it. It is very expen$ive though. I will only use Mylar anymore. Just one continuous 1/2 inch wide strip wound in a spiral around the coil with a small gap works better.

[dfbowers]

TGSL - promising improvement

In one of the other posts entitled "Metal Detector -Upgrade for Greater Depth- 25% to 30% " I decided to dig a little deeper on what this guy was selling, and here is the only thing I could figure:http://metaldetectorsnow.co.uk/4-99-...garrett-etc-2/

Certainly not my idea .. but with the way that the TGSL reacts to EMI - robbing detection range, why not try a quick and dirty experiiment.

I clipped this off of an old PC power brick and Voila! Pretty early to tell, but it believe it DOES tend to improve detection range. I have to get out of subjective mode now and take some hard measurements. Noise measurements to follow.. Simon, you HAVE to try this..

Don

[simonbaker]

In one of the other posts entitled "Metal Detector -Upgrade for Greater Depth- 25% to 30% " I decided to dig a little deeper on what this guy was selling, and here is the only thing I could figure:http://metaldetectorsnow.co.uk/4-99-...garrett-etc-2/

Certainly not my idea .. but with the way that the TGSL reacts to EMI - robbing detection range, why not try a quick and dirty experiiment.

I clipped this off of an old PC power brick and Voila! Pretty early to tell, but it believe it DOES tend to improve detection range. I have to get out of subjective mode now and take some hard measurements. Noise measurements to follow.. Simon, you HAVE to try this..

Don

I will try that -- will look for that "choke"... got one somewhere I think...

-SB

[turtlebowl]

Don,,, is this somehow different than those ferrite slugs sold on ebay for MD's or the same??
Ebay item #160686129804 and several more? This particular item number search
on ebay will explain what this supposedly does for detecting sensitivity etc.
I wasn't able to follow the link you provided so cannot read what it said.
PM

[dfbowers]

Don,,, is this somehow different than those ferrite slugs sold on ebay for MD's or the same??
Ebay item #160686129804 and several more? This particular item number search
on ebay will explain what this supposedly does for detecting sensitivity etc.
I wasn't able to follow the link you provided so cannot read what it said.
PM

Sorry for the bad link. Here it is again:

http://metaldetectorsnow.co.uk/4-99-...garrett-etc-2/


I have been doing some additional reading on ferrite beads and metal detectors and there seems to be some contoversy on thier effectiveness. Maybe others on this forum have investigated the usefulness of the idea before? I guess they have their place.. Just wondering if it might be here..

[satdaveuk]

Hi Don
There fitted on alot of the more exspensive 20m HDMI leads ive sold in the past to customers but to date ive never experienced any difference.
Ive only ever read negative feedback on these for metal detectors until your post but after saying that if you have seen a difference then maybe they work for these, I have a permanent one on a lead ill try and cut it out for experiments.

Regards

[der_fisherman]

Sorry for the bad link. Here it is again:

http://metaldetectorsnow.co.uk/4-99-...garrett-etc-2/


I have been doing some additional reading on ferrite beads and metal detectors and there seems to be some contoversy on thier effectiveness. Maybe others on this forum have investigated the usefulness of the idea before? I guess they have their place.. Just wondering if it might be here..

Very interesting.

The clip on ones should allow exact testing while running as you can put them on and take them off really easily. I really like the idea.

It should also be checked as to how the Tx and Rx signal are affected, just to see if there is any marked loss loss of voltage....

Regards

Andy

[Jerry]

That figures. I just removed one a VGA cable I was going to try on my next coil. Oh Well.

It does sound like it is worth trying though.

Thanks for posting it.

Jerry

[simonbaker]

Sorry for the bad link. Here it is again:

http://metaldetectorsnow.co.uk/4-99-...garrett-etc-2/


I have been doing some additional reading on ferrite beads and metal detectors and there seems to be some contoversy on thier effectiveness. Maybe others on this forum have investigated the usefulness of the idea before? I guess they have their place.. Just wondering if it might be here..

I haven't tried it yet, but trying to think how it might work. I'm guessing it chokes off any "common-mode" signal coming up the cable -- of course we don't want it to block the 14.5 kHz differential signal. Maybe it will be more important with the "grounded RX" coil configuration than the "ungrounded" RX coil configuration, because the ungrounded configuration has better common mode rejection???

One question I have is how a shielded cable responds to such a choke, and if that is different to a side-by-side pair such as a power cord. I think they work the same, but just wondering.

I still suspect that the worst noise is picked up by the RX coil and looks like the normal differential target signal, so the choke wouldn't stop it. The only way I can think to reduce it (so far) is dual RX coils which cancel the noise but don't fully cancel the target signal. But it makes a very awkward search head. I've started experiments on that.

-SB

[golfnut]

They reduce signals running up the braid.



If a device sources a lot of emi noise, these ferrites serve to reduce noise on the way out.

Same the other way round.


I would fit it at the box end, rather than the coil end.

if you are in a noisey environment and 'one' helps-- 2 should be better and so on.

Schaffner make a good one.