Higher sensitivity for the Garrett Ace

[Funfinder]

Perhaps someone has already info about this issue:

their is no more threshold background noise -
not even at highest sensitivity setting -
if the Ace is attached with the 12cm (5'') sniper coil.

I wanna changed it, to get maximum possible depth out of this coil.

If the sensitivity gets set like with a variable resistor it could be
pretty easy to modify the PCB for raising the standard values.

[Silver Dollar]

Well you could change R16 to 100k or so;


Or change R16 to 100k and make R15 a 100 ohm pot for variable gain...

[Funfinder]

Thx for your help. I have replaced now the R16 with a 100K resistor.
It was a cool tinker-tainment but seems it hasn't changed anything.

The Ace 250 with sniper-coil still is completly quiet at highest sensitivity setting,
even with alot e-smog sources nearby.

Usually this is not possible, because the batteries are cut off after opening the housing,
but I have modified it for additional USB power source so I could try out
all kind of resistors from 33K to 550K but even the values higher than 100K
don't make any difference into direction higher sensitivity.


btw. I found out what can be done with the variable-resistor in the middle of the PCB:
With a short turn counter-clockwise it make the detector more senstiive for small gold-nuggets.
Of course this only makes sense if the small coil is in use, but it can be used to improve the
depth of the usual sized coils for very old, rusty and small iron-relics.

Removing the 1mm tiny SMD R16 also was a new challenge...
I ripped it carefully away with a very small screw-driver. Worked perfect.

[scrungy_doolittle]

Well you could change R16 to 100k or so;[ATTACH]31829[/ATTACH]Or change R16 to 100k and make R15 a 100 ohm pot for variable gain...

Does anyone have the rest of the ACE scematic?

[Funfinder]

Garrett Ace 250 Sensitivity Mod

(this mod also should work for the Garrett Euro Ace, Ace 350 and 150)



Perfect - meanwhile I found a functioning method to raise the sensitivity!


If the resistor R16 (47.5K) is higher, the sensitivity for the detection gets shifted into direction small iron.
With those two variable resistors on the PCB the whole metal range from tiny rusty nail to large silver can be adjsted.


If the detection range is more adjusted to iron the Ace is more sensitive to that
and if its more adjusted to noble metal its more sensitive for silver and alu etc.


Here are the depth differences with the 12cm (5'') Garrett sniper coil (also see attached picture) :

adjusted to iron:
--------------------
2mm screw: 4cm
1cm thin rusty wire: 10cm
roman copper coin: 16cm
musket-ball: 17cm
silver coin 33mm diameter: 20cm


adjusted to noble metal:
------------------------------
2mm screw: not detectable
1cm thin rusty wire: not detectable
roman copper coin: 14cm
musket ball: 20cm
silver coin 33m diameter: 24cm


How the mod works:
Instead of the originally SMD resistor R16 a 47,5K resistor in line with a variable 10 to 20k Ohm resistor is used.
---> Garrett_Ace_250_Sensitivity_Mod.jpg

This means R16 now can be adjusted (from the outside) from 47,5K to 57,5K or even 67,5K Ohm.

A higher R16 resistor makes the Garrett more sensitive for iron.

If the variable resistor is at its minimum (40-100 Ohm) nothing has changed for the Garrett, it is sensitive
for noble metals. But if the resistor is set to maximum (10k or 20k) its extremly sensitive to very low iron stuff.

For best performance the both pots on the circuit board should be turned either left or right until the maximum gain for
silver on the one side and very small iron parts on the other side is reached.
The final result: if the variable resistor is turned to low resistance the Ace 250 is super sensitive for silver coins etc.
and if it is turned full to its max., the detector even finds 2mm screws, deep tiny coins or very small gold nuggets!


Good Luck!

[Funfinder]

btw. this mod can be used for manual ground-balancing and a 15K variable resistor works best!
In high mineralized soil tune the poti into direction iron-sensitivity to reach maximum depth.


And I have compared it with the unmodified Garrett Euro-Ace - the distance for silver coins is reduced by
25 % but therefore the Euro-Ace is more sensitive for the other metal stuff at higher mineralized ground.