SMT Bandito Info/Build

[Silver Dollar]

Yes the SMT Bandito board will work in the Tracker case. I'm not sure what to do with the TGSL.
I had bought a Tracker and a Bounty Hunter JR and planned on updating both but the SMT TGSL
never showed up so I only have the Bandito and a full size TGSL. I had just about given up on the
TGSL but now it is usable...

[Koala]

Multi turn pot solder and solder wick have turned up from China. Happy days got enough bits to start now.

Re looked at the Ivonic thread and on the first post there is a picture of the unit and it is a very old one in a large black case. Also picked up some .28 wire so can start on some coils. It's cold here at the moment less than 20C so the epoxy I am using takes a few days to set. Least with the windings I can put them in the oven. Just been repairing a car headlight and that's taken 3 day to semi harden


Thought the plan was for Bandido SMT to be going into the Tracker not the TGSL ? The board will be smaller

[Silver Dollar]

I was surprised and relieved to find it working good and getting the depth. Now to try a few different coils
and then find a box to put it in (doesn't fit in the Tracker case)...

Have you gotten all the parts to build up your board yet?

[Koala]

Wow. That's a 50% increase. With my IDX and a 27cm DD just under 40cm seems to be the up limit to work reliable. That's air test on a UK copper 2p same on an iron clad 2p. Did find that when testing it had to be in it's metal box otherwise the depth varied by a cm or more depending on the orientation of the board and cables or coil but in a shielded box and the coil on the stem the results were consistent

[Silver Dollar]

Well adding the 10k's to the 393 seems to have helped. The audio is strong now and I heard
a good beep to almost 15"! But it started chattering again so not sure if it's usable. I added
the caps but it didn't seem to make much difference. I surmise they put the threshold for the
comparator above the noise so avoid "phase jitter", not sure but they seem to make my board
work better so they stay!

Note: I also upped the audio cap to 1000uf from 220uf as shown in Ivonics loud audio mod
(I thought the speaker might be causing the supply to glitch);

[Silver Dollar]

Doing some testing with the TGSL today. It was fairly quiet with occasional peeps.
It only got the big silver to 10" so I decided to up the gain of the first filter stage.
This will also tell me where the beeps are coming from.

Well I changed the resistor to 1 Meg and cap to 100n and got my 12" in the air!
But there are now a lot more beeps and chatter. It is still much different from the
original Bandito and I'm not sure why?

The input opamp seems quiet but the LM393 output seems to jump when a beep
occurs so maybe it needs some noise suppression? It could also be coming back
through the power supply...

If you notice the Bandito uses resistors to ground on the 393, maybe I'll try that and
see what happens;

[Silver Dollar]

Well the wiring suggests there was once a center tapped coil (maybe the first generation?) there is a 5th
wire in the cable but the RX negative is tied to the shield and the TX uses the shield as negative. I believe
Ivonic rewired a stock Tesoro to his grounding scheme and it worked better. So why did Tesoro leave it wired
as it is?

They probably had trouble making those center tapped coils so found out by a slight rewire you could get
almost the same performance and didn't have to mess with the centertapping. The problem is the RX is
not really balanced and the TX can radiate as one of it's feeds is the shield!

The stock cable on my coil is 8" long too to allow hip mount so I'm going to use 1/2 of it on another unit.
It has 2 pairs with shielding on each and is soft and flexible. You can even use a centertapped coil and
ground the shield at the chassis.

I'm not sure the answer on the coils but using the stock coil on both my units the real Bandito works
much better. I'm going to try the SMT Bandito on batteries and see what it does...

You can add the Minelab Oscillator to the Bandito and run a 1 mh / 15 mh coil with it. It should work better
by 3 to 6 times but I haven't heard how much better it is. Some make the offhand remark that it's about the
same in the ground...

I'm looking for 6" in the ground with good disc and I assume I'll get around 1/2 the air results so a solid 12" in the
air should do it...

I have a bunch of Coils I made some stock, some centertapped, some shielded, some Minelab specs and a super set
with 36 mh RX centertapped. I was hoping to get the TGSL running right and use it to test different configurations but
I haven't been able to get it to work right. It is quieter now but still seems to choke up and not get the ultimate
depth. I saw 12" when it was oscillating but not now. I tried just about everything and it's still bad....

[Koala]

I was looking at this and this. Looking at the last diagram I would guess that the box of numbers to the top right were someones measured coil.


Also noticed on some of the other forums that some had tried a larger newer coil and it worked okay but others it caused chatter and require the sensitivity to be turned down that much that they go no deeper than the original brown coil

[Silver Dollar]

Well the uMax is just a micro doing the sound so I believe the coil is the same as the old technology units.

The 5 pin I have is the old brown 8" and it has no centertap on the RX. So unless the Eldorado used a special
coil it couldn't have been centertapped. There is a spare wire in the 5 pin so a center tap could be chosen
at the control end but they would have had to carry it through to my unit to make them all compatible.

Davor used his own center tapped coil on an IGSL and just had to add some extra capacitance to the Disc and
GEB phase caps so not a huge difference to make it work...

[Koala]

I am more confused than ever now. From the Tesoro site they only sell 2 types.

"It is very important that you select an accessory coil that is compatible with your detector. Our coils are divided into two series, the Delta and Epsilon. The Delta coils have 4-pin connectors; they are, also called H.O.T. (High Output Technology) coils. The Epsilon coils have 5-pin connectors and are designed for µmax coils. Check your detector to make sure you get the right kind of coil."

And elsewhere I read that the Eldorado can be used on the Bandido but if you use homemade TGSL on the Eldorado it does not work properly as the phase is out because it's not center tapped

So you have a 5 pin µMax coil on a none µMax Bandido from original. But if the thread about the Eldorado and Bandido is correct the phase will be out on your SMT Bandido because it's not center tapped. This is where I get confused Tesoro only sell one type of 5 pin coil that is advertized to work on all units ? Something does not add up. My head hurts.

Think I will have to make one of each and test.

"grounding the pots to the panel and PCB" I found on my IDX it did not make that much difference except depth testing wasn't consistent and by a few centimeters until everything was boxed

[Silver Dollar]

Well my Bandito is a Rev B non uMax 5 pin (coil) with 6 mh and 6.5 mh which I believe is correct for the
SMT Bandito II and also for the TGSL. I'm not sure if there is a Bandito II uMax that uses the 4 pin
1 mh and 10 mh coils?

Looking back the original Bandito didn't do so well in my first test but worked excellent in the last. Also I have
never run the SMT board on batteries, there might be a difference there. Also I need to get my front panel
made as there might be some effect from grounding the pots to the panel and PCB. I have the shape cut out
but need to learn a Cad or Drawing program to make a fancy panel graphic. I'd like to at least have 1 - 10 for
the Disc pot for repeatability and testing.

[Koala]

Aren't the coils designed differently for the Bandido vs the Bandido II µMax ?

reading this thread the original coil for the none µMax does not test that well for depth and a homemade coil surpasses it.

[Silver Dollar]

I measured the Disc and GEB signals to check them against my TGSL and have a picture;

These are vs TX so look funny as the RX is shifted (maybe 200 degrees? Can't tell as can't
see the RX!).

The Bandito acts much different than the SMT Bandito and TGSL. It has random noise at
high sens and clean strong signals and can detect silver to 14". The target signals look
different too;





Not sure why? The filters are a bit different with the negative feedback opamps and
some values are different too....

[Silver Dollar]

Well I finally got it working. The best I could do for depth though is 7" on Gold and 8" on silver.
I had a little more at one point but lots of falsing. I'm not really sure where it came from but
it seems eradicated (for now)...

[Silver Dollar]

It seems to be a bad connection somewhere as pressing on the board makes it go away....

I'll try re soldering everything. I had some glitching and it seemed to be caused by the
center leg on the FET broke when I reinstalled it. A new FET cured that but now that
pecky oscillation...