[x] Welcome at THunting.com!

A fun place to talk about Metal Detecting, Treasure Hunting & Prospecting. Here you can share finds and experience with thousands of members from all over the world

Join us and Register Now - Its FREE & EASY

THunting.com
Treasure Hunting & Metal Detecting Community
   
Advanced Search
*
Welcome, Guest! Please login or register HERE - It is FREE and easy.
Only registered users can post and view images on our message boards.
Did you miss your activation email?

Login with email, password and session length
Or Login Using Social Network Account
News:
Pages:  1 2 3 4   Go Down
Print
Share this topic on FacebookShare this topic on Del.icio.usShare this topic on DiggShare this topic on RedditShare this topic on Twitter
Tags:
0 Members and 1 Guest are viewing this topic.
Offline GoldDigger1950Topic starter
The Old Man and the Soil
Global Moderator
Platin Member
*****

Just call me GD.
The Old Man and the Soil
Join Date: Jun, 2009
Thank you160

Activity
34%
Male
United States
Posts: 10990
Referrals: 12

46893.00 Gold
View Inventory

Awards

Garrett Groundhog ADS, Garrett Sea Hunter, Bounty Hunter Tracker IV, Bounty Hunter Pioneer 505,Minelab Eldorado Mk II, Tesoro Compadre, Tesoro Tiger Shark & A Few Home Brew Detectors
« Reply #10 on: March 31, 2011, 09:15:37 pm »
Go Up Go Down

Quote:Posted by DOOLEY1972
here is one of those genius / nutter idea's iv'e just had,
we take a sample on the field colapse downward slope , normal ,
wonder if it would be possible to take a sample on the power up slope ??

In 99% of PI circuits, this is impossible since the same coil is used for both TX and RX. In the rest, the RX circuitry is blanked out deliberately to keep the TX signal from swamping the RX circuitry.

Keep on thinking. Don't let things like this get in the way of posing your "what if" questions.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg159107.html#msg159107




Logged

It's all about that moment when metal that hasn't seen the light of day for generations frees itself from the soil and presents itself to me.
Let's Talk Treasure!

Offline wus47
Copper Member
*

Join Date: Nov, 2010
Thank you1

Activity
0%
Male
Ukraine
Posts: 82
Referrals: 0

565.00 Gold
View Inventory

WWW Awards

hammer head PI Md, Thunder, own develop
« Reply #11 on: April 03, 2011, 04:04:46 am »
Go Up Go Down

Hi Dooley...!
In topic

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php?topic=18762.new;topicseen#new

page 2 is placed my program Pulse Induction Analyser. You can download and try for experiments (as digital processing for PI MD with sound card)
Wus47

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg159759.html#msg159759




Logged
Offline jeyjey
Copper Member
*

Join Date: Nov, 2010
Thank you0

Activity
0%

Iran, Islamic Republic of
Posts: 32
Referrals: 0

886.00 Gold
View Inventory

Awards

pi metal hunter
« Reply #12 on: May 30, 2011, 03:11:14 am »
Go Up Go Down

hi
i want make pi metal detector for search gold coins in deep about 2 meter
please help me for make this

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg177973.html#msg177973




Logged
Offline Hector
Bronze Member
*

Join Date: Mar, 2011
Thank you0

Activity
0%
Male
United States
Posts: 165
Referrals: 0

995.00 Gold
View Inventory

Awards
« Reply #13 on: May 30, 2011, 03:46:43 am »
Go Up Go Down

When building metal detector coils, what differences would one expect to see when replacing copper wire with silver?
I would think that lower resistance AND more turns might enable more sensitivity + faster on/off -high inductance for PI.
Combining multiple frequency, discrimination, depth and shape identification would be the ultimate detector.
In the future, the best detectors will combine all the successful traits. 

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg177979.html#msg177979




Logged
Offline DOOLEY1972
Copper Member
*

Join Date: Mar, 2011
Thank you1

Activity
0%
Male
United Kingdom
Posts: 99
Referrals: 0

650.00 Gold
View Inventory

Awards
« Reply #14 on: May 30, 2011, 04:59:34 am »
Go Up Go Down

in response to hector ,  silver wire has a lower resistance per meter than copper  , so on resistance is lower but not by much , so for same number of turns you can have greater power or increace to the number of turns to get slightly better sensitivity / voltage deviation for same target , but is the cost worth it for the slight increace in performance ??

i have been doing allot of experimenting over the last few months , different coils , types , how many turns and seperate TX RX coils , so far , and only built a TX front end at the moment , this is some of what i have found:

results are using oscilloscope and a 3 inch square box piece of ali 3/4 inch square resting on coil:

"standard ish coil" 10inch, 30 turns 22 swg copper enamled wire , 165us on =0.25V deviation .

dual coil 10inch, TX 30 turns 22swg , RX 100 turns 30 swg copper enamaled wire wound together , 165us on =1V deviation.
but found dual coils can be quite noisy and seem to need more damping.

best result so far 12 inch, 100 turns of 0.6mm (about 22 to 24 swg) insulated wire simple bundle wrapped:
165us on = 1V deviation and 90ma av current @120hz
with 300us on time = 2.5v deviation and 200ma av current @120hz
only thing is , there doent seem to be any deviation beyond 6inch away with sample piece , so op-amped it times 100 ,
test piece is "picked up" ay 5 inches away but can't get any more distance.

so i'm doing something wrong , people are picking up small coins at 12 inch arn't they ??

the key seems to be the coil , electronics can only deal with the signal they are presented with , "they" cant "make it up" if the signal deviation isn't there then no more can be done with the electronic side of thing's.
the holy grail is the coil in my humble opinion.

using dual coils with some transformer step up increaces the deviation yes , but the distance at which a reaction starts is the same for me .
this "problem" , metal detectors in general is now praying on my mind , and that better can be done .

incidentaly , stumbled across an easy way of discrimination , on an underdamped coil that drops to 5v below top rail on it's first rebound , then oscilates for a while after, ali lifts the oscilations all together , and steel straightens out the wobbles but doesn't make them all rise as a whole.

so , i was looking for distance and stumbled accross discrimination.

ofo into a field now to look for ringpulls , might find some gold by accident.



Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg177986.html#msg177986




Logged
Offline pamungkasdigdaya
Copper Member
*

Join Date: Apr, 2011
Thank you0

Activity
0%

Indonesia
Posts: 25
Referrals: 0

131.00 Gold
View Inventory

Awards

Pulse Induction
« Reply #15 on: May 30, 2011, 11:02:28 am »
Go Up Go Down

I am looking for the best performance VLF detector. I will build it my self. Any suggestion ?

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg178058.html#msg178058




Logged
Offline homefire
Global Moderator
Platin Member
*****

Join Date: Jan, 2009
Thank you498

Activity
100%
Male
United States
Posts: 15092
Referrals: 0

48400.00 Gold
View Inventory

Awards
« Reply #16 on: May 30, 2011, 11:10:03 am »
Go Up Go Down

You may want to look at this kit by Silverdog.  

You are not allowed to view links.
Please Register or Login

http://www.silverdog.co.uk/shop/


The TGSL is a kit based on the Tesoro Golden Saber.  Well documented here and on the Geotech forums.

A scope is a must on this one.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg178060.html#msg178060




« Last Edit: May 30, 2011, 12:02:58 pm by homefire »
Logged
Offline DOOLEY1972
Copper Member
*

Join Date: Mar, 2011
Thank you1

Activity
0%
Male
United Kingdom
Posts: 99
Referrals: 0

650.00 Gold
View Inventory

Awards
« Reply #17 on: May 30, 2011, 12:00:09 pm »
Go Up Go Down

   also plenty of VLF schematics floating around on the net, try googleing "metal detector circuits vlf" ,
lots out there , im fixated on the whole PI thing so not payed much attention to VLF designs.

try substituting the word circuit in google search for build or project , quite a few posted with full explination from start to finish.

also check out the download section on here for vlf projects or migrating over to geotech , they have a few projects as well from bfo ,vlf and pi designs.

can i mention geotech on here ?? please advise , as if it's a swear word on here then admin can delite.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg178075.html#msg178075




Logged
Offline homefire
Global Moderator
Platin Member
*****

Join Date: Jan, 2009
Thank you498

Activity
100%
Male
United States
Posts: 15092
Referrals: 0

48400.00 Gold
View Inventory

Awards
« Reply #18 on: May 30, 2011, 12:04:40 pm »
Go Up Go Down

GeoTech is good here.   At one time we were together.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg178079.html#msg178079




Logged
Offline DOOLEY1972
Copper Member
*

Join Date: Mar, 2011
Thank you1

Activity
0%
Male
United Kingdom
Posts: 99
Referrals: 0

650.00 Gold
View Inventory

Awards
« Reply #19 on: May 30, 2011, 01:21:04 pm »
Go Up Go Down

oh , now that i didn't know , was a bit cagey about mentioning the name !!



Posted on: May 30, 2011, 01:11:44 PM
forgot to ask , is there anywhere else other than here and geotech where i can get my hands on lots and lots of PI schematics ?? think ive got all there is to offer on the net , about 8 to 10 different designs , want to study more , no chance of any slightly out of date manifactures designs being out in the public domain ??

don't want to copy , just study so i can evolve , how long is copyright law ?? and the big question is , are they , the big boys secretive about there designs becouse they don't want us to know how little is actualy in the box for the oodels of money they retail for ??

my mind is hungry , need input , and lots of it , they say a little knowledge is dangerous , so need more knowledge  Devil

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,18582.msg178097.html#msg178097




Logged
Print
Pages:  1 2 3 4   Go Up
Jump to:  

Powered by SMF 1.1.19 | SMF © 2005, Simple Machines | Sitemap
Copyright THunting.com