With regard to tying off with and without resistors, did you check and see if there was a difference with regard to current used from the metal detector?
I see no reason to save on a few high quality resistors that I can buy for about $3 per 100, unless there is a positive gain with regard to current drawn from the battery.
Thanks in advance
Andy
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A couple of pictures says it all. Congratulations on getting the article published Don! You have that talent of expressing things very well in writing.
JerryLeave a comment:
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Eastern & Western Treasure Magazine.
Well they published one of my articles for the August 2011 edition! If anyone in the U.S. subscribes it's one of the smaller articles near the back. So what's this have to do with the TGSL thread? Almost all my finds over the last 2 years were made with Ivconic's TGSL version.
DonLeave a comment:
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Hi,
I downloaded a copy of your well thought out manual yesterday, a rather long time after your request for suggestions, so are you still interested in any new ideas? or are you happy with the result (I flicked through and thought it was really good, even pioneering in many respects).
By the way I have no suggestions at this time as I did not yet study it in depth (it is probably still in good order even then!!
), but just in case......
I would imagine that I am one of many, many people simply delighted by the quality and the thought you put into this extensive document.
I am going to buy one of Silverdog's kits in the near future and your "Manual" was a gift from heaven....
Regards
AndyLeave a comment:
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A few wild guesses here from someone who has made several VLF detectors, but older designs like the ETI549 for example. But I can help I feel.
Provided that you know the coil size(s), the number of turns and the wire thickness, and you follow that exactly, you should end up with two good coils.
I then wrap the coil tightly with insulating tape for its complete length to stabilise it.
Then I wrap the coil with a meter or so of bared, multi-strand tinned copper wire, making sure that the ends do not touch, with one end I leave a yard or so (meter or so) of the wire with the insulation still on it, though I probably don't need that much, this part comes away from the coil near to the exit points of the coil connections, usually between them.
This is the contact for the Faraday shield that I now start to make.
What I have used in the past is to take a meter of silver cooking foil and cut it into strips. Hold the start tightly with more insulating tape and wrap the strips around the coil, leaving an open end where the contact wire ends, at least a 10mm gap. A short across the Faraday shield is difficult to detect (joke) and correct, so be very careful.
Then using more insulating tape, tape the whole coil carefully, including the 10mm gap.
Make sure that you can identify the start and finish of the coil as some detectors, I am told, it makes a difference to the sensitivity of the whole machine, if one coil is "reversed" to the other. How true this is I cannot say.......but a swap round of the connections to one coil may improve sensitivity in some cases....just be aware.
There are several styles of coil placement, the overlapping double "D" is good as it has a wider search path, especially for items that are not so deep, but some prefer what is called the co-planar which is basically a small middle coil and a far larger coil following the surround of the head, that a loop is passed to be "inside" the small coil, so that pickup is nulled in the absence of metal.
The co-planar I have never used personally, though I have one in the making somewhere in the cellar!, always the double "D".
For a double "D", he two coils need to be laid in such a way that again the pickup on the Rx coil is nulled. In fact, I always used my wedding ring to check and I went slightly out of the null on simple machines, that was found to be the "Gold" side, simply so that if non ferrous metal was detected, the signal rose immediately, but if ferrous metals were detected, it went "back" through the null first, giving an quiet interlude before coming out of the null and producing a signal. Discrimination without the control complexity!!!
The coils need to be carefully glued down (in the well known shape)using epoxy or similar, adjusting all the time, till the epoxy is hard and the coils unable to move any further.
I used an old cotton shirt, cut into strips, filled with epoxy and wrapped round each coil as some glues do not stick to plastic tape, allowing movement, which can cause instability. Its a messy business, use rubber gloves and clean off any epoxy with methylated or de-natured alcohol, which works fine till the glue is dry!
I do believe that the method applies to many VLF DIY Projects....
I admit that although I am planning to build one of these detectors, I still have a lot to read here first and I hope that my tips are actually applicable to this design..... My full apologies to all if that is not the case.
Regards
Andy
PS. If anyone needs more details, especially about the shapes and placing of the coils, I could make or copy a few simple pictures if needed, just ask!Leave a comment:
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thank you guys, but i found on ebay http://cgi.ebay.com/3000-30-AWG-Copp...item53d74c0afe
it is the simplest to pay, and i have enough wire for 6 detectors
I just want you to confirm me that this wire is good for this metal detector !!
Thx in advance !!!Leave a comment:
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Hello!
I've just completed my first TGSL and made some field tests with it and here is some experiences and questions. Performance is so far not very good, 25cm for 1 euro coin and vegetation is giving false beeps. I think I borked the shielding when trying to "slot" it to reduce eddy currents and to get a better null. So I got noticeably lower rx voltage but most of the slots ended up as several millimeter holes in the aluminum tape.
Next coils are going to have probably low conductivity shielding but can't find much information on this. Can you give any advice on this? Does graphite paint work or maybe some conductive plastic like carbon tape? I also tested coloring a piece of painters tape with ordinary pencil, it seems to make a thin and promisingly cheap alternative.
I also found that I can possibly identify difficult trash objects like rusty bottlecaps or rolled foil if I vary swiping speed. These trashes seem to make a shorter beep if search head is swiped faster and disappear completely if swiped even faster. Disc was set to reject thin foil pieces. I would like you to confirm this.Leave a comment:
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That's good to know, brand new stuff.
This surplus dealer looks cheaper but you be the judge (it's your money).
(but they don't always have stock.)Leave a comment:
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Magnet Wire AWG 30
I have found enameled wire to make a coil here:
--- AWG 30 1/4 lb. 821.75 ft. In Stock $10.50
Cheap shipment available (USPS Priority Mail $5.95)
How much wire do we need?
Approx: 2'1" (per turn) x 220 turns = 458 ft.
It is sad that 821.75 ft. is only enough to make one coil set.
May be it is better to buy 1643.5 ft. to make at least 3 coil sets in case something goes wrong:
--- AWG 30 1/2 lb. 1643.5 ft. In Stock $19.12Leave a comment:
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Hello, i have poblem with buying copper wire. Can you please tell me where can i buy wire online. I prefere ebay but i can't find copper wire there!!!
please help !!!Leave a comment:
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Of course you're not going to have discrimination if your detector ALWAYS rings.Originally posted by 08llyj View PostGreeting
always not succeeds has make work the detector d 'eduardo (silverdog pcb).My coil is:
rx 6.55 mh and 13.5 ohms
tx 6.17 mh and 17 ohms
the detector always rings ,i haven t discrimination.
help me
Do you have a multi-meter and have you checked power supply voltages?
Have you checked to see if you have tx output?
How could you expect help with your problem based on the scant information you provided?
edit: I don't believe that your coils are so far out of whack that it would cause constant tone. Look for something else.Leave a comment:
Inspiring!
Leave a comment: