Search Coil for Project's

[simonbaker]

Are there any commercial PI-MD's that use concentric induction balanced coils?

Tinkerer

I think Tinkerer has interesting idea as a mod. Build a PI which can switch between the two coils of a standard concentric - you can use either big or small. Should be pretty easy to do switching -- not sure how it affects the processing circuit. It would be better if bucking coil could be removed, but if TX coil is "open" (disconnected"), then bucking coil will not drain as much energy.

The problem probably is the unused coil will "ring" and overshadow the target - but maybe still a usable signal. Experimenting would tell.

Another interesting possibility - connect TX and RX in series reversed, so RX "bucks" the TX - make a deep seeker that ignores shallow targets in the center. Or connect them in series same direction and make super pinpoint with deep backup (just guessing - need field simulation to see the patterns - Aziz?). A good area for experimentation.

I have been realizing some of the advantages of PI detector more and more. Problem of IB is no perfect way to null coils - always give up something -- either off center (Double-D, OO), reduced magnetic field (bucking coil, omega), assymetric coil sizes (concentric). PI is "perfect" geometry because TX and RX are the same so perfect symmetry. But nothing is perfect - PI must look at tiny part of signal because of timing - still, good to not need nulling of coils.

I want to look again at single coil induction ideas. BFO maybe not so bad in principle compared to PI - both are all metal in a way. Another idea - I want to experiment with single coil induction "loosely coupled" to an oscillator so phase shift happens and can be detected - maybe I'm smoking something, I don't know, will take time to research it.

[Tinkerer]

Phase shift observation with PI

I think Tinkerer has interesting idea as a mod. Build a PI which can switch between the two coils of a standard concentric - you can use either big or small. Should be pretty easy to do switching -- not sure how it affects the processing circuit. It would be better if bucking coil could be removed, but if TX coil is "open" (disconnected"), then bucking coil will not drain as much energy.

The problem probably is the unused coil will "ring" and overshadow the target - but maybe still a usable signal. Experimenting would tell.

Another interesting possibility - connect TX and RX in series reversed, so RX "bucks" the TX - make a deep seeker that ignores shallow targets in the center. Or connect them in series same direction and make super pinpoint with deep backup (just guessing - need field simulation to see the patterns - Aziz?). A good area for experimentation.

I have been realizing some of the advantages of PI detector more and more. Problem of IB is no perfect way to null coils - always give up something -- either off center (Double-D, OO), reduced magnetic field (bucking coil, omega), assymetric coil sizes (concentric). PI is "perfect" geometry because TX and RX are the same so perfect symmetry. But nothing is perfect - PI must look at tiny part of signal because of timing - still, good to not need nulling of coils.

I want to look again at single coil induction ideas. BFO maybe not so bad in principle compared to PI - both are all metal in a way. Another idea - I want to experiment with single coil induction "loosely coupled" to an oscillator so phase shift happens and can be detected - maybe I'm smoking something, I don't know, will take time to research it.

I was talking about concentric induction balanced coils for PI.
But you mentioned about the ringing of one of the "open"
coils. I have experimented some with that and have observed phase shift of the ringing coil to the right for FE and to the left for non-FE.
It might be worth investigating further.

Tinkerer

[simonbaker]

I was talking about concentric induction balanced coils for PI.
But you mentioned about the ringing of one of the "open"
coils. I have experimented some with that and have observed phase shift of the ringing coil to the right for FE and to the left for non-FE.
It might be worth investigating further.

Tinkerer

I see what you're saying - IB pulse makes sense too, why not? Should make the receive signal stand out more you'd think for various processing like discrimination. You lose the beautiful geometry of single coil. Maybe in the end it doesn't gain enough over IB continuous. I wonder if theoretically with good signal processing, if you spread the same power over time (like comparing pulse to continuous with same geometry), you essentially get the same detection. But practically, one of the two may be easier to engineer. Will be interested in what you find.

[Unregistered]

sd2000 coil

can help me abaut sd2000 coil

[[email protected]]

Alonso Pisoldetector coil

Hello friends!
I can help with information about Alonso coils, which he used to gun detector? I know it is a TX-RX-type coil BFO, but has many turns and the wires used?

[Qiaozhi]

Hello friends!
I can help with information about Alonso coils, which he used to gun detector? I know it is a TX-RX-type coil BFO, but has many turns and the wires used?

Probably the best place to put any information about the Alonso pistol is in the Remote Sensing Forum.

[Gwil]

Just want to check that I understand the Tejon coil shown in post #5 and following - the small coil in the centre has only two wires, therefore there is no transmit bucking coil there, only a receive coil. Hence there must be a second (bucking) receive coil close to the larger transmit coil, as shown in Carl's "Coil Basics" article, Figure 12.

(See http://www.geotech1.com/pages/metdet/info/coils.pdf )

Have I got this right?

Gwil

[Qiaozhi]

Just want to check that I understand the Tejon coil shown in post #5 and following - the small coil in the centre has only two wires, therefore there is no transmit bucking coil there, only a receive coil. Hence there must be a second (bucking) receive coil close to the larger transmit coil, as shown in Carl's "Coil Basics" article, Figure 12.

(See http://www.geotech1.com/pages/metdet/info/coils.pdf )

Have I got this right?

Gwil

No - there are actually 4 wires going to the inner coil. You can see them in post #5. The nulling coil is in series with the outer TX coil, and is wound around the inner RX coil in anti-phase.

[Gwil]

Hi Qiaozhi

You are of course quite right, I had failed to spot the two very thin wires.

Thanks,

Gwil

[lunamay]

hi
i would like to know the walue of original TESORO SILVER SABRE UMAX COIL parameters..if anyone knows them..is it concentric or DD?

best regards

[Qiaozhi]

hi
i would like to know the walue of original TESORO SILVER SABRE UMAX COIL parameters..if anyone knows them..is it concentric or DD?

best regards

http://www.geotech1.com/cgi-bin/page...oils/index.dat

[lunamay]

thanks..i saw this page sometime ago..but still wondering..is "umax" means that silver sabre u max and golden sabre u max has the same values?(of cours with same coil diameter) if so than i'm wery glad to know this

best regards and thx for answer

[Qiaozhi]

thanks..i saw this page sometime ago..but still wondering..is "umax" means that silver sabre u max and golden sabre u max has the same values?(of cours with same coil diameter) if so than i'm wery glad to know this

best regards and thx for answer

I think they are the same.

[baht7]

Search head eti1500

what do u guys have on a DIY search head design for the eti1500?
If I end up trashing the project Ill need a supplier for the search head.
Thxs
Gary in Bangkok

PS if I find the Lost Japanese Gold in Thailand, Ill buy a real detector.

[amtech2005]

what do u guys have on a DIY search head design for the eti1500?
If I end up trashing the project Ill need a supplier for the search head.
Thxs
Gary in Bangkok

PS if I find the Lost Japanese Gold in Thailand, Ill buy a real detector.

Hello Baht7 . Do not trash the project . Check out page 7 of the "Magnum" pdf file I posted here . Both projects operate just above 15 khz . And I believe some older Tesoro search coils may also work well , just make sure the pin configuration is correct . So you do have a few options . Also make a comparison of the transmit and recieve sections of both schematics . Now you have enough information to make a decent home made Metal Detector .

Best Regards.............Eugene