northwest The need for big deep gold detectors.
Welcome, Guest. Please login or register.
Tuesday November 19 2019 15:32:36 AEDT PM
Home Help Login Register
News: Welcome to the Australianelectronicgoldprospectingforum founded in July 2010, an add free totally independent forum with over 70 boards and paid for and managed by the Admin.Topics: 9,612  Total forum Posts:47,584 Members:861. Total page views:12,976,190  Admin and  forum and domain name owner :marjen at optusnet.com.au. Guests can only see a limited number of boards at present and cannot see any hot links. Guests cannot post and never will be permitted too!Registration of new members must be approved by admin.
 All  original Photos and posts and  original materials displayed on this site are COPYRIGHTED and remain the property of the poster and the  Austalian electronicgoldprospectingforum.com. All messages on this forum express the personal views of the author and should not be interpreted as necessarily being in accord with those of the forum owner and neither the owner of this forum and its domain name nor SMF or the forum software developers or the forum host shall be held responsible for the content of any message. Admin reserves the right to remove any offensive or objectionable posts. No defamatory material or politics/religion or issues of race will be permitted.
QED news
QED on facebook
link-https://www.facebook.com/groups/245308699667153/403446933853328/?comment_id=403472030517485&reply_comment_id=403476793850342&notif_id=1562580344994993&notif_t=group_comment
Interfacion Pty Ltd is pleased to announce that the QED PI Detector has been modified to allow the use of DD (double D) coils. This change involves a simple change to the electronics within the control box.
The firmware has also been upgraded to include a further improved Ground Balance.
All detectors being delivered to new customers from Monday 5th August 2019 will already have the above upgrades included.
As a show of commitment to all QED owners, the hardware modification to allow use of the DD and CC coils will be provided at no cost.
Of course and as per the QED warranty, the firmware update is provided free of charge, except for P&H.
Any QED owner who plans to attend the Laanecoorie Bash is encouraged to bring their detector along and have it upgraded at no cost.
Standard postage and handling arrangements apply to other owners. Send via Australia Post the box (minus batteries) along with a pre-paid, pre-addressed bag/box to:
Interfacion Pty Ltd
PO Box 106R
Redan VIC 3350
Howard Rockey
Director Interfacion Pty Ltd.

australian electronic gold prospecting forum.com  |  Detector Technology and Electronics and new detectors  |  Detector Coils (Moderator: Goldman)  |  Topic: The need for big deep gold detectors. 0 Members and 1 Guest are viewing this topic. « previous next »
Pages: 1 ... 32 33 34 35 36 37 [38] 39 40 41 42 Go Down Print
Author Topic: The need for big deep gold detectors.  (Read 29372 times)
Muntari
invited members
Junior Member
****
Offline Offline

Posts: 414


« Reply #740 on: Tuesday April 24 2018 12:11:34 AEST PM »

Hi Alex,

This coil at 510 kHz SRF would still have relatively low capacitance though, so it should perform well.

cheers

Muntari
Logged

All posts submitted by myself to this forum are my opinion and are done so without prejudice
autitch
Newbie

Offline Offline

Posts: 44


« Reply #741 on: Tuesday April 24 2018 21:48:05 AEST PM »

Hi Alex,

I've measure a bunch of coils that I have and here are the results.  You will notice that my measured results vary from what was previously posted by IBGold however one can get a sense of the order of the SRF between coils. 

NF EVO 12" - SRF 622 kHz, 309 uH, 212 pF calculated
NF EVO 14"x9" - SRF 653 kHz, 298 uH, 198 pF calculated
NF EVO 17"x13" - SRF 613 kHz, 309 uH, 218 pF calculated
NF ADVANTAGE - SRF 633 kHz, 291 uH, 217 pF calculated
COILTEK 16" GOLDSTALKER - SRF569 kHz, 310 uH, 252 pF calculated
COILTEK 14" DD - TX SRF 464 kHz RX SRF 272 kHz without damping resistor ( damping resistor 559 Omhs in parallel)
ML COMMANDER 11" - SRF 634 kHz, 290 uH, 217 pF calculated

In my opinion the increased sensitivity of the flat wound coils compared to the bundle wound coils is due to the winding creating a better / more efficient antenna when the mono coil  receives a signal from a target. 

Except for the Goldstalker all the other monos all have a very comparable SRF.  Inductance is about 6% higher for the NF EVO 12 compared to the ML COMMANDER 11 and the ML has slightly higher SRF however the EVO is a more sensitive coil.  I suspect that what is holding back all commercial coils including the NF EVO flat wound coils is the relatively high capacitance of the coil.  On assessment, different winding techniques haven't improved the SRF unless the coils have been tuned to maintain similar SRF between flat wound and bundle wound coils by playing with the capacitance of the coils. 

Has anyone cut a foot from the coax cable on a flat wound coil to see the infield results?

AuTitch


Logged
Alex
Newbie

Offline Offline

Posts: 69


« Reply #742 on: Wednesday April 25 2018 15:52:39 AEST PM »

Thanks autitch great info.
Logged
GARY
invited members
Hero Member
****
Offline Offline

Posts: 567


« Reply #743 on: Wednesday April 25 2018 19:42:52 AEST PM »

  

NF ADVANTAGE - SRF 633 kHz, 291 uH, 217 pF calculated

In my opinion the increased sensitivity of the flat wound coils compared to the bundle wound coils is due to the winding creating a better / more efficient antenna when the mono coil  receives a signal from a target. 



I would agree with you in regards to the increased sensitivity of the Flat wound mono over the Bundle wound mono.

BTW what size coil was the NF ADVANTAGE ?

Gary.
Logged

"The more you know, the more you know you don't know."
autitch
Newbie

Offline Offline

Posts: 44


« Reply #744 on: Wednesday April 25 2018 21:00:35 AEST PM »

The NF Advantage is 16" round.

AuTitch
Logged
Muntari
invited members
Junior Member
****
Offline Offline

Posts: 414


« Reply #745 on: Wednesday April 25 2018 21:24:54 AEST PM »

  
  

NF ADVANTAGE - SRF 633 kHz, 291 uH, 217 pF calculated

In my opinion the increased sensitivity of the flat wound coils compared to the bundle wound coils is due to the winding creating a better / more efficient antenna when the mono coil  receives a signal from a target. 



I would agree with you in regards to the increased sensitivity of the Flat wound mono over the Bundle wound mono.

BTW what size coil was the NF ADVANTAGE ?

Gary.

Thanks for posting your findings Autitch

Ditto, I agree, more wire turns exposed to target but also less capacitance.
Using different coil lead length and/or different types of coax material will in my opinion, have much more effect on Cp than most well constructed coil windings and then you have connectors, solder joints, shielding, critical damping, mosfet Coss etc. It truly is a trade off on the system as a whole.
Coils have come a long way in recent years, hats off to the coil manufacturers but I think they can still be improved and the coil leads should definitely be put front and centre of any new design..my 2 cents worth anyway

Cheers

Muntari
Logged

All posts submitted by myself to this forum are my opinion and are done so without prejudice
IBGold
invited members
Junior Member
****
Offline Offline

Posts: 489


IBGold at home.


« Reply #746 on: Thursday April 26 2018 14:43:39 AEST PM »

  
  
  

NF ADVANTAGE - SRF 633 kHz, 291 uH, 217 pF calculated

In my opinion the increased sensitivity of the flat wound coils compared to the bundle wound coils is due to the winding creating a better / more efficient antenna when the mono coil  receives a signal from a target. 



I would agree with you in regards to the increased sensitivity of the Flat wound mono over the Bundle wound mono.

BTW what size coil was the NF ADVANTAGE ?

Gary.

Thanks for posting your findings Autitch

Ditto, I agree, more wire turns exposed to target but also less capacitance.
Using different coil lead length and/or different types of coax material will in my opinion, have much more effect on Cp than most well constructed coil windings and then you have connectors, solder joints, shielding, critical damping, mosfet Coss etc. It truly is a trade off on the system as a whole.
Coils have come a long way in recent years, hats off to the coil manufacturers but I think they can still be improved and the coil leads should definitely be put front and centre of any new design..my 2 cents worth anyway

Cheers

Muntari

I agree in my view higher performance coils can be made as we are not bound by the constraints of  the commercial builders we can take the time to optimize the winding,the former materials and thicknesses, shield types and coax types and lengths personally I run shorter coax lengths than most, coil to detector + 100 mm with coax securely fixed to shaft with just enough excess to re terminate the plug if and when required I could go on about Coax design requirements but commercially it goes on deaf ears so I have given up. 

Regards, Ian.  happy face 
Logged

Regards, Ian.
Alex
Newbie

Offline Offline

Posts: 69


« Reply #747 on: Friday April 27 2018 17:13:47 AEST PM »

Hi Ian ,yes coax.I find not only the capacidence to take into account but the coax I been using raises the uh about 25 uh for 1.2 mt length.I was thinking about trying a twisted pair.
Logged
IBGold
invited members
Junior Member
****
Offline Offline

Posts: 489


IBGold at home.


« Reply #748 on: Saturday April 28 2018 16:00:49 AEST PM »

Hi Alex,

Yes I have tried most coax's available in Australia and homemade coax as well as twisted pair's shielded and unshielded there are pro's and con's for all but I have yet to find anything I am really happy with but while I am out of action for the next six weeks or more I have plenty of time to think about it.

Regards, Ian. happy face
Logged

Regards, Ian.
gef12
invited members
Hero Member
****
Offline Offline

Posts: 583



« Reply #749 on: Sunday April 29 2018 10:11:37 AEST AM »

Have found in my collection of coax " Prolink interconnect s-vhs cable"  about 20pf / ft .... but inner core is rather thin ..
might be good if just using the Rx coil.
Have DD coax (from the tx side) measuring 45pf  .. lost the rx side somehow.... may have used on another project.
Logged

Maybe 2013 is the Year of the Nugget ... EFFEN hope so :-)
IBGold
invited members
Junior Member
****
Offline Offline

Posts: 489


IBGold at home.


« Reply #750 on: Monday April 30 2018 16:31:50 AEST PM »

Hi Geff,

The best coax I have found is a Soundlink one From Wess Electronics or    . AIC227 It is low capacitance 7 mm OD but stranded OFC copper and the center conductor could be bigger but if firmly mounted to shaft so it cannot move works OK I have not tried their AIC228 though but that could also be OK and it has a heaver center conductor but is 8 mm OD it is a pity they do not do them with either tinned or enameled strands.

Regards, Ian.
Logged

Regards, Ian.
WM6
invited members
Supreme Hero Member
****
Offline Offline

Posts: 2007



« Reply #751 on: Monday April 30 2018 17:16:06 AEST PM »

Hi Ian

What mean declared "super low capacitance"? How much per meter of length?

"Heavy duty PVC Jacket" is nice read too.
Logged

Global capital is ruining your life?
You have right to self-defence!
Aziz
invited members
Supreme Hero Member
****
Offline Offline

Posts: 3977



« Reply #752 on: Monday April 30 2018 22:45:15 AEST PM »

  
Hi Ian ,yes coax.I find not only the capacidence to take into account but the coax I been using raises the uh about 25 uh for 1.2 mt length.I was thinking about trying a twisted pair.

Hi Alex,

the rise of 25 uH of the coil inductance is oved to the measurement error in conjunction with higher coax capacitance and high test frequency.
1.2 m coax cable won't add such a huge inductance.
Try to measure the inductance at low frequencies (100 Hz, 120 Hz or max. 1 kHz). The higher the test frequency, the higher the wrong inductance reading will be due to higher capacitance effects.

Cheers,
Aziz
Logged

Free science, knowledge and inventions to the mankind.
Aziz
invited members
Supreme Hero Member
****
Offline Offline

Posts: 3977



« Reply #753 on: Monday April 30 2018 22:52:12 AEST PM »

Hi all,

pity, I don't have much time to show you my self-made RX coax cable.
It is really easy to build and cheap too.

Measured capacitance:
31.68 pF/144 cm (6.7 pF/ft, 22.0 pF/m, @10 kHz measurement frequency)
31.46 pF/144 cm (6.6 pF/ft, 21.8 pF/m, @100 kHz measurement frequency)

The assembly principle can be applied to a true litz wire based TX coax cable too (both core and shielding as litz wire solution). But I haven't built the TX coax cable yet.

Cheers,
Aziz
Logged

Free science, knowledge and inventions to the mankind.
Muntari
invited members
Junior Member
****
Offline Offline

Posts: 414


« Reply #754 on: Tuesday May 1 2018 11:04:58 AEST AM »

Hi Ian,

I have sent an email to WES regarding the AIC228 cable capacitance as it does not state it on the listing.
Might get some if it looks ok.

Had my eye on some other shielded microphone cable @ 22pF per metre but then fell off my chair when I looked at the price $1850 for 300 meters and they only sell in 300m quantities...German made stuff... it can wait I think  happy face

Cheers

Muntari
Logged

All posts submitted by myself to this forum are my opinion and are done so without prejudice
Muntari
invited members
Junior Member
****
Offline Offline

Posts: 414


« Reply #755 on: Tuesday May 1 2018 11:38:51 AEST AM »

Hi Ian and All,

Ok, WES says the Cp of AIC228 is 19.4pF per ft.

Cheers

Muntari
Logged

All posts submitted by myself to this forum are my opinion and are done so without prejudice
WM6
invited members
Supreme Hero Member
****
Offline Offline

Posts: 2007



« Reply #756 on: Tuesday May 1 2018 15:37:54 AEST PM »

  

Ok, WES says the Cp of AIC228 is 19.4pF per ft.

Muntari


Thanks Muntari.
About 60pF per meter. Not really "super low" as stated, but acceptable.


Quote from: Muntari

... fell off my chair when I looked at the price $1850 for 300 meters....



Ha, ha, hope it is only a typo and in fact it is $300 for 1850 meters.
Logged

Global capital is ruining your life?
You have right to self-defence!
Muntari
invited members
Junior Member
****
Offline Offline

Posts: 414


« Reply #757 on: Tuesday May 1 2018 16:46:37 AEST PM »

Hi WM6,

It's Belden Brilliance 2221 2 core + shield, stupid prices but good cable.

There are also a few guitar cables which are essentially coax that will do the job nicely with Cp ranging 38-55 per metre.

Also, as Gef12 has mentioned, some video cable is suitable. Look for studio and stage cables, there are plenty of flexible types with braided shield.

All in all, Ian's find, is not too bad for the price, readily available, just have to save some Cp from the coil construction.

I'm waiting on pricing for low Cp guitar cable atm and will post once I hear back from distributor.

cheers

Muntari
Logged

All posts submitted by myself to this forum are my opinion and are done so without prejudice
IBGold
invited members
Junior Member
****
Offline Offline

Posts: 489


IBGold at home.


« Reply #758 on: Tuesday May 1 2018 16:53:30 AEST PM »

The AIC 227 is 17pf per foot from memory.

Regards, Ian. happy face
Logged

Regards, Ian.
Alex
Newbie

Offline Offline

Posts: 69


« Reply #759 on: Tuesday May 1 2018 20:18:37 AEST PM »

  
  
Hi Ian ,yes coax.I find not only the capacidence to take into account but the coax I been using raises the uh about 25 uh for 1.2 mt length.I was thinking about trying a twisted pair.

Hi Alex,

the rise of 25 uH of the coil inductance is oved to the measurement error in conjunction with higher coax capacitance and high test frequency.
1.2 m coax cable won't add such a huge inductance.
Try to measure the inductance at low frequencies (100 Hz, 120 Hz or max. 1 kHz). The higher the test frequency, the higher the wrong inductance reading will be due to higher capacitance effects.

Cheers,
Aziz
Logged
Pages: 1 ... 32 33 34 35 36 37 [38] 39 40 41 42 Go Up Print 
australian electronic gold prospecting forum.com  |  Detector Technology and Electronics and new detectors  |  Detector Coils (Moderator: Goldman)  |  Topic: The need for big deep gold detectors. « previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2006-2009, Simple Machines
Simple Audio Video Embedder

BisdakworldClassic design by JV PACO-IN
Valid XHTML 1.0! Valid CSS!