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Hi Chet thanks once again for all your help at this stage i dont oscilloscope yet i have read a few posts on the ones for $49/$69 dollars every body seams to think they are good value for money. i will also have to read on use of them i am chasing some wire that you have recommended you are a champion mate will keep you up to date how i am going have a great day Kindest regards kellogs
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In addition to Chets advice I would highly recommend 24 or 26 awg 600 VOLT INSULATED TEFLON OR PTFE WIRE I use the silver plated stuff and have seen no degradation from the silver plating probably because of the small wire gauge. Do not get the silver wire that is bonded in a bundle with silver plating...less is best. The 600 v insulation helps greatly to reduce capacitance and that is what these coils are all about. Be sure to put the outermost winding lead at system ground to insure self shielding will work. Do not flood the coil with anything just overwrap and fiberglass it. Do use a continuation of the coil wire as a twisted pair feedline to eliminate any lead/solder junctions in the field of the coil and to minimize capacitance.
Regards,
DanComment
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Great thanks to every one from kellogs
Hi baum 7154 sorry a bit late on the reply been out thank you for the added advice and have taken it on board have been chasing the wire on the net think i have found what you suggested thank you once again i love this forum every body works together i haven't seen a bad spoken about any one great will keep you posted Kind Regards kellogs
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Hi kellogs; a few additional thoughts for testing your new coil. Per balum 7154’s advice about avoiding a solder joint in the coil area;
Start the inner winding with enough slack wire coiled up to reach the detector box. Tape this coil bundle together because it’s going to dangle in the way while you wind around the coil form.
After you wind the 40 turns leave enough outer winding wire to form a twisted feed line with the inner wire and connect both to your detector. Before twisting it mark it so that you can identify it for proper connection to the detector. The outer wire is connected to the circuit ground.
Accomplish the first test measurements then cut the lower end of the feed line outside winding wire near the coil to unwind the first coil turn. Then solder it back to the end of the twisted feed line wire it was cut from. Proceed with testing and unwinding turns. This process will keep the overall capacitance of the circuit constant and close to its final configuration. The excess loop of wire lying away from the detector and coil will have little effect on the circuit capacitance or inductance while testing.
When you have finished testing; untwist and remove the short (1 m) cut ground side wire from the twisted feed line.
Then twist the surplus loop wire around the inner wire and connect it to the detector ground circuit. If this surplus wire does not reach the detector then a necessary soldered splice will be outside and some distance from the sensitive area of the coil.
You previously expressed some interest in detecting in the bush. The small aluminum and lead targets will simulate gold nuggets well enough to achieve as much sensitivity from the detector as possible with this coil.
If you have a small ring or small piece of jewelry add it to you tests. Rotate the gold item to the weakest response or shortest distance for comparison.Comment
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For a small piece of jewelry I would avoid any solid ring because its geometry makes it a very strong target due to strong eddy currents. A small pierced earring stud or tie tack stud is a pretty good target in 14kt to 18kt gold. Also a gold dental cap or crown is a pretty good target.
For an aluminum target a pretty tough target is a 6mm X 6mm square cut from a soda can. I think you will need to get your sample delay adjusted down to about 10us or less in order to see it and you must have a fast coil to operate at that delay. With this coil you are on the right track. If you can't see the 6mm X 6mm cut a piece of soda can 1cm X 1cm and try it.
Regards,
DanComment
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Hi chet i have read you excellent post i think i follow i am making my pattern to day for my coil and picking up some 600v teflon coated 24 and 26 agw tinned coper wire as well i thank you very much for your time and patients if i run into any problems i will talk to you as well as keep you up to date thanks Mate and to all Kindest Regards kellogsComment
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Hi baum 7154 i have been out all day chasing the wire recommended to no avail was just truing to be quick should have known better will have to order on line have found a place so that is good i have made mu coil pattern will try doing the winding with string as has been suggested thanks for your great post again and advice do you know any thing about the oscilloscopes that have been posted for about $49 and $69 dollars just have to talk my wife in to it any way mate will talk to soon Kindest Regards kellogsComment
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The only place I've ever seen tinned copper teflon wire is here; http://www.surplussales.com/Wire-Cable/Wire4.html
It looks like they still have some left..Comment
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----------------------------------Originally posted by kellogs View Post
You are most welcome and I find a lot of help here on most any topic.
I neglected to say that the 24 to 26 AWG coil wire should be STRANDED not solid.
I don't really know much about the new scopes for under $70 but would make sure that the scope is capable of at least two channels and can display down to at least 1us or less is better.
DanComment
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Hi kellogs; I agree with baum 7154 on oscilloscope requirements. The flyback pulse and target return require a good oscilloscope frequency response. The oscilloscope should have a bandwidth of 10 MHz or higher. Another concern is the size of the screen. If you have really good eyesight a small screen may be ok.
Before you get to deep into this hobby you should thing ahead on what your goals are and how to meet them. It’s like hunting and fishing you can get wrapped up in getting all of the best/right gear but not getting into the field often to see that you don’t use much of the gear that you acquired.
After you get this new coil built you should get out and give the detector and yourself some time to evaluate where you want to go next.Comment
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Hi silverdollar/baum 7154/chet thank you all i have located a place on the web called ( element 14 ) and they have a lot of products worth while looking.i will have to save up to purchase an oscilloscope but have taken your advice thanks one again for all your in put and great help talk later Kind Regards kellogsComment
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Hi to silverdollar /baum7154 /chet and all other members i am going to be off line for a few days have to Finnish off the bathroom renos and also waiting for my wire just wanted to let you know so thank you once again good hunting and look forward to catching up shortly stay safe Kindest Regards kellogsComment
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I find it annoying when household duties get in the way of detector and coil building!
DanComment
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hello geocash1,you seem to be the right person to ask about this basket coil and the winding of it, could tell me what you do with the ends of the two wires once youve completed the 5 loops for each wire ,do you join them or leave them open,obviously the other ends of the two wires go to the mpp board ,hope you or any one could help,thanks.Comment
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2 wires? I used one wire and had 2 ends left which went to the MPP...
http://www.thunting.com/smf/index.ph...;attach=110353Comment
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