HOW TO MAKE MAGNUM COIL?

[Unregistered]

Hello,
Can someone tell me how exacly I should make and conect the coil for MAGNUM METAL LOCATOR?Old hobby sweet circuit!
I saw in one russian translation that they use пел 0,2 for transmiting coil and пел 0,13 for reciving coil!
Have anyone made good goil himself?

[Unregistered]

HOW TO MAKE COIL for magnum metal locator?

HOW TO MAKE COIL for magnum metal locator?

[porkluvr]

wire gauge selection

Hello,
Can someone tell me how exacly I should make and conect the coil for MAGNUM METAL LOCATOR?Old hobby sweet circuit!
I saw in one russian translation that they use пел 0,2 for transmiting coil and пел 0,13 for reciving coil!
Have anyone made good goil himself?

http://geotech.thunting.com/cgi-bin/...gnum/index.dat

The original Magnum article states 32 SWG (0.274mm) for transmit, and 36 SWG (0.193mm) for receive coils. If you have assembled the detector but have a problem, be specific about the nature of your problem.

Recommended that you stay close to the original coil's design (including wire diameter) unless you are capable of making adjustment with an oscilloscope!
(That doesn't mean that an oscilloscope wouldn't be good even when you exactly copy the coil!)

[Unregistered]

To porkluvr

Hello,
Thanks for the fast reply!
I have made the PCB-s,but I have tested it whit coil that I have made.And its look like I haven't make it right!

Which point do you take from coils for screens?
First layer of 5a fuse wire?Make a point from the AL foil?Take the second layer of 5A fuse wire or take them all?

Then I have to connect the 4 screens on the cable to 1 pin of the 5-pin DIN plug and the same point of the socked to the screens point on the frontend PCB?

One friend told me that I should not make Faradey shield for the TRANSMITING COIL is this true?

I see that in Russion translation of the MAGNUM METAL LOCATOR they write that you should use 32 SWG(2,0mm)for L1 and 36SWG(0,13mm) for L2?????
Why they say so?WHICH IS RIGHT?

[porkluvr]

use proper wire

We have a disagreement in the diameter of the proper wire to use.

http://www.simetric.co.uk/siwire.htm (you'll have to convert inches to mm to use this)
http://www.dave-cushman.net/elect/wiregauge.html
There are others.

Understand that 0.2mm wire size is almost double the resistance of 32SWG (0.274mm), and .13mm is more than double the resistance of 36SWG (0.193mm).

The exact F-shielding (Faraday shield) method of your coil should not affect basic operation. Stability may suffer if you don't F-shield the transmitter coil; you may have false targets - but the detector should still function, and may function very well. I recommend you stay close to the original design on your first attempt.

It is possible to tie upper and lower layers of fuse wire together, then make only one connection to the cable shields. (This will get doubled - read the next paragraph) With the aluminum foil in between the two layers of wire there will be a good F-shield connection.

Remember to leave a gap in shield. That means that the fuse wire should also not be continuous. Stop the wire where the foil is gapped. This doubles the number of segments of fuse wire to be connected together. Make shield uniform and swmmetrical - as you can, but remember, it doesn't have to be perfect. If you achieve a coil that works very well then it may be easier to replicate your work if you have been meticulous.

>>Then I have to connect the 4 screens on the cable to 1 pin of the 5-pin DIN plug and the same point of the socked to the screens point on the frontend PCB? This sounds OK.

If it's not too late, it is probably best to not wrap the foil directly over the wire. Leave some distance. 2mm, 5mm, who knows. Might not make any difference - but it won't hurt. You have probably spiral wrapped with lacing tape and that should be good enough. Maybe do it if there is a next time.

Again I say, if you have a problem - be specific in describing it. What do you mean by "It looks like I haven't made it right"? That doesn't provide much information.
Are you having trouble nulling the coil? What are you doing to test receive coil null? What test equipment do you have access to?

Read the threads on Concentric coils at other places in this forum. They are very similar to the "4B" or "pinpoint" coil you are building. Search "coplanar" and "concentric".
See the coil article here

http://geotech.thunting.com/cgi-bin/...&file=info.dat

White's coil patent: http://geotech.thunting.com/pages/me.../US4293816.pdf
Gotta go.Good luck!

[Unregistered]

To porkluvr

Hello,
Thanks.I try nuling whit the simple circuit that is shown in the design,because I dont have scope!
But cant find OA47 diode and replaced it whit 1n4148!
Can this affect the procedure?
I have tryed to wind my first coil whith 0,30mm for L1 and 0,19 for L2 and it wasnt working well!!?!?!
The machine was able to detect metal,but it were liking big objects!
And were geting coin at 2cm whit bad disck?
This is my first project?
Now when I see your oppinion I think that the nuling maight be my probleme?
THANKS AGAIN

p.s.What do you think why the Russian translation gives a differen almost double
cooper wires?

[porkluvr]

no 1N4148

You absolutely need to use germanium diode OA47, 1N34, 1N270 or similar. Or, I think you can use Schottky like 1N5817. Schottky diodes were not yet invented back when this project was developed (or they were very rare and expensive). A diode with low forward voltage drop is imperative and Schottky is OK, maybe. I have not tested this possibility and so I don't know for sure.

But, I do know a 1N4148 is not good to rectify small current that you will need to resolve. Sensitivity will suffer and discrimination will be weak unless you use proper set-up and are very careful to null!

The 0.3mm and 0.19mm wire should be very good for coils.
I can't say why russian translation is different, but I'm pretty sure that whoever translated from English to Russian did a much better job than I could do if it was the other way around!! Mistakes sometimes creep in, even when languages barriers don't exist. Little details, ow!
Later!

[Unregistered]

Hello,
I cant find OA47, 1N34, 1N270 or similar!Or 1N5817!
Its look that the nearest thing is 1N5819!!!Its in the description of 1N5817 datasheet,but I see that have a little diferance in some values!
Will this work?Shell I try?
Thanks again for your fast replys!

[porkluvr]

Aieeee

Don't do it. Get datasheet from diodes,com and look at curves for forward voltage. You can plainly see that 1N5819 has a much higher forward voltage than 1N5817.
http://www.diodes.com/datasheets/ds23001.pdf

Better to use 1N34 or OA47. Remember that I wrote that I have not tested
1N5817??? Do not use 1N5819. I don't have to test that to know it's bad.

You have gone to a lot of trouble to get this far. This is like pulling weeds in your garden. Are you going to pull some weeds and leave the rest? Do you read the newspaper with moonlight?

Use the right "tool" for the job. If you ain't got it, get it!!

[Unregistered]

hi

Thanks
You are right!
I am beginner,but I have serched for OA47 and could not find it in my country!
Then I look in google and find that I can use also 1N34, 1N270,......as you have told me;But they are also unaveilable for me!!!!!!
So I saw hope in this 1N5817 but I can find only 1N5819!
You see....that is why I have asked you because I see that you are in things!
I awso see this different values,but I have to ask!

The only germanium diode that I have found so far is GA101,but I cant see its values to compare whit OA47 in datasheet!??!?!?!

Did you think that could work?

[Unregistered]

hi

And I will still search for the right tool as you told me!
I will try order online from somewhere too.

[porkluvr]

diode test

I wish I could tell you OK, but the information I found was not very positive. I found some GA101 data to indicate a higher Vf (forward voltage), similar to silicon. Is it a power rectifier??

You need a signal diode with Vf as low as you can find. If you have a multimeter with diode test function, use it to test what you have. A ge diode should measure about Vf=0.2V ~ 0.3V. Silicon is about Vf=0.6V, at low current.

These numbers depends on the supply current used during the test, which reminds me: if you have a voltmeter and a few parts you can create a test for diode forward voltage!

Connect battery, diode and resistor in series and measure voltage across diode. Limiting current to below 2ma is good. If you measure diode Vf=0.3V or less, it's probably good enough to use. Remember the null circuit needs two ge diodes.

For a 1.5V battery, use about R=1.5kΩ. For 9V battery, R=10kΩ is good. Doesn't have to be perfect. Measure Vf on 1N4148 and compare results.
Cheers !

[Unregistered]

HI

Thanks!
I will try and will contact you again!
You help me very much.