Another P.I. link

hi please shematic + mods maybe this week i made it. best regards

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http://www.thunting.com/smf/index.php/topic,3797.msg190581.html#msg190581

good thinking zavier , minor point , m13 doesnt exist , a nut that fits a 13mm spanner is called an m8 , there graded to the dia of the bolt they fit same as the 1/2" nut ,its called a 5/16 , but yes , i knew what you ment , and good idea , an m8 nut or its imperial equivelent should be available all over the world for testing and referance purposes.

that's the ferrous test done , how about something standard for the non-ferrous and poss something higher up the conductivity scale ??

have found that for some reason that a small piece of brass sheet , i used 0.8mm thick , 15mm square piece , gives the same responce to the decay curve on the oscope as a 9ct gold ring ,

as alot of us have poss found , on the decay curve of a pi , steel "lifts" the end of the slope first, gold or eqiv lifts the first part of the decay first and ali lifts in the middle first , so if only a single sample machine ,dependant on where it samples , depends on what its most sensitive to ,

so 3 standard metals required for testing purposes ,

so we have the m8 or 5/16" nut for ferrous

brass for responces higher up the conductivity list , but cant think of anything standard here ,

only standard piece off alu i can think of is poss a drinks can ring pull minus the "flap" that on the new cans stays with the can , but the ring can be bent off , and as long as the ring is cut in one place to prevent it giving off more eddy currents accross the whole range ,

good luck on getting the world standardized ,

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http://www.thunting.com/smf/index.php/topic,3797.msg190658.html#msg190658

hello xavier ,

haven't got scope set up , its packed away , but here is an accurate pic i have done for you to show what is happening ,

hope this helps ,

Posted on: August 11, 2011, 05:55:01 AM

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oh , by the way xavier ,
pc scope programs that use the sound card / mic input are not very good for what we are doing ,

i tried that idea early on , on a laptop (borrowed our lasses , she wasnt happy)
but most sound cards "auto center" the signal after a few seconds ,

so can never compare 2 signals , they move around , good for visual , but not much else , so i went out i bought a second hand phillips pm3217 ,
works well and for £40 with no test leads , was a bargain i think , she is a big old lump , but she works fine.

Posted on: August 11, 2011, 06:01:52 AM

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just checked pic , it's not come out very clear ,

the top black line is no target ,
the green line is alu and copper ,
the red line is steel and iron ,
and the blue line that dipps at the bottom is gold and brass ,the brass i used is that model makers brass tube 1" long ,
and flattened so as it did not form a ring.

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http://www.thunting.com/smf/index.php/topic,3797.msg190675.html#msg190675

Ha well this is great we are getting somewhere a lot quicker than most (All governments) LOL
Thanks Dooley for the drawing and thanks 6666 for the cct these are some of the things that makes Thunting.com such a great place.

Regards Xavier

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http://www.thunting.com/smf/index.php/topic,3797.msg190682.html#msg190682

Xavier

Dooley what is the inductance of your coil? on one of your posts you were saying that you used 25 turns 0.6mm hookup wire. 

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http://www.thunting.com/smf/index.php/topic,3797.msg190686.html#msg190686

Xavier