PI Fig. 8 Coil for Bench Testing????

[Mechanic]

HI Bill,

Rule no.1 for selecting a shielding material for a coil..... If you can detect it, you cannot use it for a shield.
Al-foil will be no good for a shield.
You will need a shield, otherwise when you wave your hand over the coil you will get a response and then you will think the response is coming from the 0.02g speck in your hand!
Use Stefans thin wire strand shielding method, it is easy to make and very effective.

Also the other thing you want to consider is the self resonant frequency of the coil. Compare it to your others, which should be at least 100khz.

With the inductance a little bit under will be fine, this will also help to raise the self resonant frequency. Some commercial coils have a lower inductance and seem to work fine, they just draw a bit more current.

Cheers Mick

[BillNEWAST]

Hi, Guys I have been down for a week almost with a "$Recycler.Bin Trojan RootKit". I had tried almost everything in my toolkit to fix it and Then Googled "recycle bin folder virus removal tool" and found a site that explained how to remove it. I then went to MalwareBytes site and downloaded the "Anti-Rootkit" beta version and for the next 2-3 hrs Chased the damned thing around on my Laptop till I got rid of all of them and came up CLEAN!!!!!
This thing goes to each harddrive and usb drives and any other drives it can get on and makes the RecvycleBin into its personal residence. All the files you delete to the Recycle Bin are NOT deleated, but It just Adds some code to the File on the end and then set the attrib flags to [read only] [archive] [system] [hidden] RASH and it shure was.
All the other virus checkers and things I tried wouldn't touch the damn thing due to the flags being set, But they would SURE tell me that it was there.
There were Numerious problems with the Registory also that I had to REMOVE by hand as Nothing but this MalwareBytes could touch them also.

Well Got my female coil end yesterday so got the ANTIFERENCE Coil wound and attached to the SD2200V2 today and it Works just fine.
Will tell about that in next post. how I did it and what it took so anybody can duplicate mine to use on a bench.

Mick I SODA Blasted off the White Paint on one side of one board and both sides of the POWER and COIL board.
DO you think that I need to start a new thread on doing a reverse engineer of the Power/Coil board or should I RESURECT the old "SD2200V2 Noisless Power Supply Thread and have all that info CONTAINED in one SPOT/thread.
PIC's will follow in what ever thread we do decide.
PS it makes things so much easire to ID with the White STUFF OFF.

YES PUN INTENDED!!!

Sincerely
Bill Adams

[BillNEWAST]

Final Fig 8 coil specs and pics!

Well here is the my final figure 8 antiference Bench Coil.




I used 60ft (18.28M) 18awg Twin lead Speaker wire from Rshak pn:279-008 clear. I seperated the zip soldered ends with 2 overlaping shrink tube to reach apx the dia. of insulation on wire.
I wound 19 turns on the coil form previously pictured. Then I tested for ohms and inductance and had to unwind 1 loop. Then I wraped packing tape to hold the coil togeather and then took 30agw magnet wire and wound around and round as in pics. I started from the side of the coil from where the 2 windings come togeather and wraped till I got to the Left hand. I then made a Loop and then continued winding down the other side of the coil, back to the start, leaving 1/8"+ between windings.



I had to wait till I got my 5 pin CB Mic connectors to get the MD to settle down. When they go in I tested the fit and It was too Tight/Small, not like the ML ends. So I took my Digital Calipers and found that the OD on the plug was within a couple of Thou's, so when I measured the Id on the Pin holes, I discovered that the ML Plug Hole was 20 Thou's larger. Well I stripped the Plug, under the MicroScope and removed the Pin Conectors from the plastic plug. I used a pair of 4" vicegrips to hold the plug, with two layers of clean greaserag for cusion. I found that the 1/8" drill bit in the drill press running at 2000rpm did a Perfect job of REAMING out the little buggers. When I reinstallled the pins I used an exacto knife and small flatblade screwdriver to spread the female pins. I had to reset the Stop on the underside of the solder end of the pin so it wouldn't pull out again. I installed pins 1,2,4,&5 as pin 3 on the connector of my machine isn't connected inside the box.



I didn't have any Coax attached to the coil yet but wanted to test it so I just soldered in 4 numbered jumpers so I could test it. Worked Perfect NO More 60hz + interference.



I did some testing on the coil and found that it would pick up an US 25c coin at 16-18" (40-45cm). this was from center of both coil loops, But from the Cross over it registered ZIP.
I'm thinking that maybe if the coil was Squished from the long side and the Coil Leads were made to exit at the crossover loop then you could build a MONO Antiference Coil????

Anybody have any thoughts on that???

Sincerely
Bill Adams

[Mechanic]

G'day Bill,

Well done on the coil, looks nice! The only thing I would have done different is to add some sort of spacer between the coil windings and shield as this reduces capacitance, making a faster coil. I used bubble wrap on mine, but normally people use spiral wrap of some sort, preferably made from a material with a low dielectric constant. But in saying that it seems to be working for you just fine.

As for the reverse engineering, I would start a new thread for this.

Cheers Mick

[Ferric Toes]

Figure 8 coils are great for minimising interference. I was able to run a SD2200 quietly in a lab and close to a cellphone tower with one of these, whereas with a normal mono it was impossible. I prefer a double square version as you get a more intense field around the centre bar as it has double the conductors all the way across. Coins flat do give a double response with zilch in the middle. Coins on edge give a good response centred on the middle bar. A sphere gives a uniform response in any direction and peaks over the centre bar. For nugget hunting in noisy areas this is a good coil as nuggets are usually irregularly shaped and at any orientation. The coil in picture is a small one, but I have made them of all sizes up to 5ft x 2.5ft overall but with the bar in the long dimension. Good for towing on a sled or vehicle mounting broad side on to give great and fast ground coverage.

Eric.

[Davor]

I call these tanga string

Concentration of current in a centre bar resembles a lot the DD coil middle section and pronounced sensitivity there.

[BillNEWAST]

Mick, I figured that the Thick insulation of the speaker wire would offer some insulation to the shield wire. I know it isn't perfect but it's a good enough so I can get some work done on the bench.

Eric, below is the pic of what I ment by squishing the coils, it's almost what you have done in your Square D (pun intended) Design. And Yes the paper I did the drawing on is my start of the sd2200v2 reverse engineer. Thats why I didn't want to make a NICE Picture, I'm tired of makeing SCALED drawings for tonight.

Eric I just couldn't help but notice that you pic is so Nicely Sized and is still Clear and ONLY 72 kbytes large, how do you do that???????

Sincerely
Bill Adams

[Ferric Toes]

Mick, I figured that the Thick insulation of the speaker wire would offer some insulation to the shield wire. I know it isn't perfect but it's a good enough so I can get some work done on the bench.

Eric, below is the pic of what I ment by squishing the coils, it's almost what you have done in your Square D (pun intended) Design. And Yes the paper I did the drawing on is my start of the sd2200v2 reverse engineer. Thats why I didn't want to make a NICE Picture, I'm tired of makeing SCALED drawings for tonight.

Eric I just couldn't help but notice that you pic is so Nicely Sized and is still Clear and ONLY 72 kbytes large, how do you do that???????

Sincerely
Bill Adams

Largely by trial and error. Here is a demo picture which started out as 3.98Mb as imported off the camera. I then put it into Paint Shop Pro 6 (there are later versions but I have not bothered to upgrade). I then click IMAGE on toolbar and scroll down to RESIZE. In the box PIXELS/IN I type 200. IMAGE WIDTH type 4in. The image height automatically reduces to 3in. I then save that as a .jpg and rename. The file size has gone down by a factor of 100 to 39Kb, which takes up about 1/2 page width on Geotech so you can get two pictures side by side. Image size on Geotech comes out at double the 4in on my screen but what the heck, it is a good size still, and very clear. Obviously if you want a bigger or smaller picture, just adjust the width. Sound a bit long winded but once you get the hang of it, takes about a couple of minutes. I'm sure other picture editing programs can do the same.

Picture is the underside of a Vallon PI mine detector coil. I thought these were figure 8 type, but when I got one on ebay it was just a straight mono. The crossbar is just for strengthening. I like the shape though, and it would look smart for a fig 8.

Eric.

[BillNEWAST]

Eric, Thank you so very much. I have been struggling with the size of pics in both dimentions and # of bytes for a long time. But I just haven't taken the time to learn all the quirks of Gimp and Irfanview. I usually just use Irfanview to reduce the kbyts but haven't been able to get the pics to shrink in dimention YET. I also use Paint.net and save as a png. I also use Inkscape for some things.

Have to go now as my OLD Dell Inspirion 9100 has "The Black Screen of Death" and I will have to repalce the backlight or the video invertor or both??? But for now I'm going to St. Vincent Depaul and get one of their, used Monitors for $20-30. IF they work. I'm taking the Dell in to test them with.

Sincerley
Bill Adams

[Mechanic]

HI Bill,

If you use paint.net, then you have the tool to reduce image dimensions and the file size.
In Paint.net, load your picture,
Go to the image menu at the top and select resize.
In the width box type a number, say 1000(pixels) and it will automatically adjust the height. click ok.
Your image is now smaller.

Now when you save the image, goto the file menu and click "save as..."
Select your desired save location and name,
Select save as type : jpeg, click ok
Then it comes up with a screen where you can adjust the file size by sacrificing image quality.
There is a slider bar at the top left corner, adjust this to where your file size is acceptable and the image quality still suitable.
Ckick ok, your are done!

Cheers Mick

[BillNEWAST]

Here is my first try at Shrinking my pics!



Thanks Mick and Eric I'll keep trying till I get it right.

I have a better pic of the 2200 cktbrd.
I'll send it to you if you want?
I have to put grid lines on it so we can reference the chip at A:1 on the board. A row would be at the top of the baord and 1 is the column #. Then the chip/s are referenced inside that Address. This chip # will also be used in a Spreadsheet with the Stock chip at the beginning of the row and the substitutions in the row after and then have breif comments at the end. I'll use the Landscape orentation so there is enough Columns to print on one sheet front and back.

I'm tired for now, last night I started to layout a grid in TurboCad Pro, but when I got it almost ready to set the lines, I noticed that it was a Mirrored Image like looking from underside the board in reverse, I just Killed It and was going to finish it today but spent all day Looking for a Monitor Cable, it was in the Last Place I looked(te he, always is). Got a bunch of other Sorting done also. AND I got a makeshift camera Jib arm mount made, so I can get directly over the top of the board, I'm playing with different light sources to get the tracks to standout when I'm Zoomed in on the full 4Mb images. Its hard to get enough light and still not get the glare and get the traces to stand out Clearly on the baord.

Sincerely
Bill Adams