Serbian "Most Wanted"

[CDI]

Here is pcb with pot's.

[CDI]

good resalt CDI
What is the version you build?
can you put a pic of your circuit board
and coil informations (diametre turns & inductance)?

Hi totob, my pcb version is from ivconic, with 555 timer.
Coil parameters i can tell only for RX, cause TX is finished long time ago, inuctance is 1.03mH, resistance 3.4 ohm. Not remember how many turns and wire diameter, but somewhere between 0.45 and 0.55.
RX 175 turns, 0.25 wire, resistance 30.8 ohm, 15.09mH.
TX capacitor 480n, RX 62n.
Similiar coil parameters like Minelab Musketeer coil.

[totob]

I finished my smw, i got average depth, about 36 cm for 1 eoro coin. Good thing is that the detector is rock stabile, no instability in room beetwen wifi router and power sources in my house.
Discrimination is near perfect, hot rock fully rejected, ferite rod and nails. Here is my connection for search coil, from head to pcb.

All wires going separate from search head, at the and of cable ( in connector) shield for TX going togheter with TX minus, the same thing with RX.

Red wires are hot connection's, green are minus, and violet is shield.


[ATTACH]34614[/ATTACH]

good resalt CDI
What is the version you build?
can you put a pic of your circuit board
and coil informations (diametre turns & inductance)?

[CDI]

I finished my smw, i got average depth, about 36 cm for 1 eoro coin. Good thing is that the detector is rock stabile, no instability in room beetwen wifi router and power sources in my house.
Discrimination is near perfect, hot rock fully rejected, ferite rod and nails. Here is my connection for search coil, from head to pcb.

All wires going separate from search head, at the and of cable ( in connector) shield for TX going togheter with TX minus, the same thing with RX.

Red wires are hot connection's, green are minus, and violet is shield.

[sinclairuser]

yes basically they connect to the board.

[CDI]

basically some detectors can have all there shield connections to one wire or even the braided shield wire if coax is used, this design needs separate wires for tx shield and rx shield they connect in the detector enclosure to the enclosures shield, separating them can make a noticeable difference when the cable moves around when detecting(falsing), it can help with sensitivity to wet grass too i understand.
so when done this way you need cable with enough wires to keep shields separate untill the enclosure.

Never tryed this method, cause i never used coaxial cable(but i will try next time)
If i understand good, we need here 6 wires, right?
TX start
TX end
RX start
RX end
TX shield
RX shield
All this is clear, but when we separate shield's from both coil's in search head, they are not separated in pcb. I wanna say, they must be togheter in only one hole on pcb.
Dont undestand me wrong. Just my opinition.

[totob]

ok CDI it's clear now thank you

[sinclairuser]

Everything is clear here, but: "but goes separatelly through cable" (i mean, how we can separate tx and rx shield from only one cable)
My connection:
RX start: separate
RX end: separate
TX start: separate
TX end: separate
Shield: I maked two wires from shield, one for TX and one for RX, they both (wires) going together from search head to cable shield.
This connection work for me.

basically some detectors can have all there shield connections to one wire or even the braided shield wire if coax is used, this design needs separate wires for tx shield and rx shield they connect in the detector enclosure to the enclosures shield, separating them can make a noticeable difference when the cable moves around when detecting(falsing), it can help with sensitivity to wet grass too i understand.
so when done this way you need cable with enough wires to keep shields separate untill the enclosure.

[CDI]

Why not? You can pot coil housing in two layers.
First layer painted with graphite (with assured ground contact too of course).
You can also paint isolated RX coil (alone or additionally to mentioned two layer) with graphite shielding.

WM6, did u mean to paint tape insulated coil?

[CDI]

Can any one explain this paragraph taken from ivconic post 28 in page 2 (Wirements in search head are different than at TGSL. Al faraday cages are wired togather, but goes separatelly through cable, and are conected to cable shield. TX and RX leads also goes separatelly. So 4 leads cable with common shield is proper for this setup).?

Everything is clear here, but: "but goes separatelly through cable" (i mean, how we can separate tx and rx shield from only one cable)
My connection:
RX start: separate
RX end: separate
TX start: separate
TX end: separate
Shield: I maked two wires from shield, one for TX and one for RX, they both (wires) going together from search head to cable shield.
This connection work for me.

[Koala]

That's the same way Whites do it also. I have just made a Tesoro coil and found it preformed better on wet grass done this way also.

[WM6]

so there is no way (i think) to apply graphite on bottom side.

Why not? You can pot coil housing in two layers.
First layer painted with graphite (with assured ground contact too of course).
You can also paint isolated RX coil (alone or additionally to mentioned two layer) with graphite shielding.

[totob]

Can any one explain this paragraph taken from ivconic post 28 in page 2 (Wirements in search head are different than at TGSL. Al faraday cages are wired togather, but goes separatelly through cable, and are conected to cable shield. TX and RX leads also goes separatelly. So 4 leads cable with common shield is proper for this setup).?

[Koala]

Yes you can't use without a shield except for testing.

Did not use a shell for my last build. Coated some card for the shield then fibre glassed it above and below the coil.

[CDI]

yes you are right i mean the receiver coil (RX) so shield the rx side

Thank's Bernte.

Koala:
The main problem about graphite spray shield is that i cant find/make coil shell with cover, so there is no way (i think) to apply graphite on bottom side.
What about your type without use any shield? Soil in my hunting area is middle mineralised. Never tried or maked detector without shield, i'm afraid it can be very unstable without shield.