IDX-PRO+VDI

[mohandes]

Hi Mohandes

I can see you have put a lot of effort into getting this to work. Well done.

You were on 35 or 36 cm with 22n+12n+2.2n I would go back to this

You can not get lower than 1 volt on pin 6 of U1 this is due to the nulling of the coil. You can try moving a small piece of ferrite between the coils. Hope you have not left the oscilloscope on 10X an easy mistake to make. If you can not null your coil then this will affect the detection distance.

Can not think of anything else that would help here unless there is some interference somewhere or metal nearby as my coil nulled fine. Anyone any ideas.

You are using using a LF347 as some alternatives have been know to cause problems.

A cheap set of earbuds (in ear headphones or earphones) are very good for testing PP mode it is much easier to pick up the change in threshold tone than a speaker.

Nothing jumps out at me as an error on your photographs but they are a little blurry

Hope this gets sorted soon

hi
for testing i am turning new coil today
i put it my result
about nulling just mr golfnut can say reduce depth or increase ?(for add the sttachment )
and probs in *1
regards

[golfnut]

The impact of a poor null is DC offset on the mixer output and partial compression. As the filter amp post mixer has a cap on its FB resitor - it has no gain at DC, thats why we get away with it.

These switching style mixere using cosmos switches have a really high IP3 so there is really no need to work for weeks trying to get below 200mV.


I found a fair few small roman earlier in the summer (20 or so) with a coil null of 2 volts pp. !!!!

I added ferrite to get it down and I operate at ~ 230mV with no real issues. Be sure to kepp an eye on the phase of Rx signal whent using ferrite as the amplitude and phase change.


Mohandes - Im suprised you got an IGSL coil to work here as they are set up differently...

Does your IDX reject ferrite and Iron and accept coins with a single beep at the pass. Plus does the iron have a single beep at the pass?

Did your TGSL work well with this coil??

S

[mohandes]

The impact of a poor null is DC offset on the mixer output and partial compression. As the filter amp post mixer has a cap on its FB resitor - it has no gain at DC, thats why we get away with it.

These switching style mixere using cosmos switches have a really high IP3 so there is really no need to work for weeks trying to get below 200mV.


I found a fair few small roman earlier in the summer (20 or so) with a coil null of 2 volts pp. !!!!

I added ferrite to get it down and I operate at ~ 230mV with no real issues. Be sure to kepp an eye on the phase of Rx signal whent using ferrite as the amplitude and phase change.


Mohandes - Im suprised you got an IGSL coil to work here as they are set up differently...

Does your IDX reject ferrite and Iron and accept coins with a single beep at the pass. Plus does the iron have a single beep at the pass?

Did your TGSL work well with this coil??

S

more hard too me ,sorry.(simple languege)

These switching style mixere using cosmos switches have a really high IP3 so there is really no need to work for weeks trying to get below 200mV.

ok but i think , buy a one Euro and next test it and i dont no cosmos switch(in my language translate not) ???

Im suprised you got an IGSL coil to work here as they are set up differently...

Does your IDX reject ferrite and Iron and accept coins with a single beep at the pass. Plus does the iron have a single beep at the pass?

Did your TGSL work well with this coil??

i have not ferrite to set GEB pot and discrimination not work ( i think should first set it)
but today i remove cap between pin5 and 8 ne5534 and more depth and have 450mv p-p.(above coin detect 32- 34cm , and i know should be under 200mv p-p)

for ring gold and silver have middle depth(15-20cm) and but discrimination.
i am not build the TGSL detector.
any way i am today make concentric coplaner coil and it is finish, this coil is need shielding? how connect shielding to TX RX and BX coil? ( i think dont need)
TX 510UH
RX 35mh

oh mr golf nut you say coil of IDX and TGSL different , can you say me the master coil of IDX
regards

[Koala]

"oh mr golf nut you say coil of IDX and TGSL different , can you say me the master coil of IDX
regards"

Think I can answer this one as something has got lost in the translation.

The windings and capacitors are different

The shape is the same.

[mohandes]

Concentric Coplaner coil

hi guru
i finish the coils but neeed connection to the board and together
please show me.

regards

[paku]

hi guru
i finish the coils but neeed connection to the board and together
please show me.
[ATTACH]26949[/ATTACH][ATTACH]26950[/ATTACH][ATTACH]26951[/ATTACH]
regards

do you mean connection like this

[Koala]

One thing that has not been mention recently is its best to ground the coil connector and pots as well.

[mohandes]

do you mean connection like this

[ATTACH]26954[/ATTACH]

thanks
are you sure?
dont need shielding?
can you put for me connection for DD coil like pic above that you send it .( i ask my another friend but i need to be sure)
regards

[Koala]

thanks
are you sure?
dont need shielding?
can you put for me connection for DD coil like pic above that you send it .( i ask my another friend but i need to be sure)
regards

Shielding is very important in the real world.

If the coil is still on the bench for testing less so.

I used post 1348 worked first time for me

Connecting the coil connector and pots to the outer edge of the PCB board made my detector more consistent and stable. Might even be marginal deeper

Same for DD wind both the same way and mark the start ( I tied a knot in the start)

[mohandes]

Oh
i think my connection for DD coil is wrong
just for TX coil error .(start in P8-1 and end in P8-2), i INVERSE soldering on the board please see the pic and you see my write by Red and Green and Blue colors.
ok i shielding CC coil and connect it, befor say me #1926 correct?or my connection correct(sorry mr paku become i have UNCERTAINTY connection)
regards

[Koala]

I get

Shield
RX End
RX Start
TX End
TX Start
Not too important you get a double beep swap the RX over.

All the best with your new coil.

[mohandes]

i connect to board but problem
rx have 5.3 p-p and Rx ref can not set to ziro why?
i check it tomorrow again
merci

[Dixix]

hi
this money for Iranain(says 2000Rial), and about depth are you sure it is good?
yes i use TGSL coil(DD) and 27.5Diameter.

oh realy i an read it ( your coin ) and write it(outer) :السابع من نیسان الذکر الخمسون لتاسیس حزب البعث العربی الاشتراکی
read this
http://www.baladee.net/?articles=topic&topic=4148

best wishes

Thank you, Mohandes.

[golfnut]

I think the same as Koala - dont get hung up on Start and End of windings....


If when you test it you get a double beep from a coin pass you can either

Reverse the Rx coil teminations ( this phases th Rx signal 180 about )

OR

Reverse the Tx coil terminations this does the same - do not reverse both or you will be back at the start.

Get the best Null you can before you pot it and dont have the coils near metal while adjusting.

Test with ferrite to assess ground reject.
Test with Iron for Iron reject.
Test with gold, silver, bronze for targets you want.

Only when Iron can Disc out
Only when Ferrite can be remove
and
Only when accept all wanted alloys with single beep on pass

THEN Pot it and finish off

Otherwise you make lots of scrap coils and the hobby turns a bit dull

S

[mohandes]

I think the same as Koala - dont get hung up on Start and End of windings....


If when you test it you get a double beep from a coin pass you can either

Reverse the Rx coil teminations ( this phases th Rx signal 180 about )

OR

Reverse the Tx coil terminations this does the same - do not reverse both or you will be back at the start.

Get the best Null you can before you pot it and dont have the coils near metal while adjusting.

Test with ferrite to assess ground reject.
Test with Iron for Iron reject.
Test with gold, silver, bronze for targets you want.

Only when Iron can Disc out
Only when Ferrite can be remove
and
Only when accept all wanted alloys with single beep on pass

THEN Pot it and finish off

Otherwise you make lots of scrap coils and the hobby turns a bit dull

S

very hard
i do it , just have 7.1volt p-p for my cc coil for TX.
TX 32turn 0.7mm wire in 20cm circle(510mkh)
RX 443 turn in 8.6cm circle 0.2mm(34.7mh and 78 ohm),directly connect to board
BX 12turn around RX .by 0.2mm wire(start connect to finish TX )then start of TX and finish of BX get to board.
i do your guid mr gulfnut but just have 7.1volt ,when i remove BX coil and connect directly Tx coil to the board have 12to14 volt p-p or derease cap parralel TX and have mor voltage, why???
regards
i go college and two days i am not here .
regards