SMT Bandito Info/Build

[Silver Dollar]

Well I was reading that Tesoro used a 3 turn because it was cheaper. The 10 turn is easier to tune GB with.
The GB is very sensitive. I'm not sure if you want to use shielded or plastic ones...

[sinclairuser]

when did silverdog sell these boards?, i check the shop weekly for anything new but seem to have missed these.

[Koala]

when did silverdog sell these boards?, i check the shop weekly for anything new but seem to have missed these.

Started here
Looks to have come from here
Was experimental and not on Silverdogs website you had to ask via the contact form on the website


Someone was getting a reliable 37cm and an iffy 40cm on a 5 kopek. By using a different spec coil. Did mean to look up how big a 5 kopek coin was but never got round to it. (lost the link also )

Having said that depth is not what the Bandido II umax is about.

[Silver Dollar]

I didn't know he had those too. Someone in another forum mentioned it and I emailed him and scored the last one!

I've been playing with the layout and might have some made one of these days but I didn't see much interest for
people buying some if I had some made.

I got the passive components installed today. The only ones giving problems are the big caps as I'm trying to use
surface mounts for them. I got 2 installed (220uf's) but might have to put the 100's on the back.

I have a 4066 but none of the other chips. I'd love to send and order and get this board going quick but I have to
wait for my SMT TGSL to get here so I only send one order...

I used some different values for a few parts as I didn't have the correct ones so my board might not be a good
one to compare to the original Bandito I have coming. By the way I've seen some Bandito's and Golden Saber's
selling on ebay for around $120. That's a good deal considering what it costs to make one.

[Silver Dollar]

Here's a pic of the transistor that doesn't fit showing how much pad you have to work with;



Here's what I got done so far. I found some small SMT 100uf caps.

[Silver Dollar]

So I drew the schematic in Express so I can make mods to it;

[sinclairuser]

Started here
Looks to have come from here
Was experimental and not on Silverdogs website you had to ask via the contact form on the website


Someone was getting a reliable 37cm and an iffy 40cm on a 5 kopek. By using a different spec coil. Did mean to look up how big a 5 kopek coin was but never got round to it. (lost the link also )

Having said that depth is not what the Bandido II umax is about.

i was just suprised as i had not seen them, sd's shop is a bit sparse of late, wanted a hh kit and an idx kit but none in stock, i know he is waiting for idx boards, i just hope i have not missed the boat on the hh.

[Silver Dollar]

Well my real Bandito will be here Thursday or Friday so while waiting I've been looking at some of the other
Tesoro MD's and wondering why some are touted as going deeper and some have sweeter tones as they are
very similar. The newer ones seem to have no restrictions on depth whereas the older ones "hit a wall" and
wouldn't go deep even on big targets.

In looking at what mods could be done to try and improve the Bandito I found several that would be easy to
try. One is to leave the 4066 out and use the opamp from the battery circuit and a 4053 to use both polarities
of the input signal. A little tough as the parts are surface mount but I have a scrap board with a 4053 on it
that I can cut up to make a tiny daughter board.

Adding the Minelab oscillator will put 150 ma into the coil verses 32 ma stock. With the AB+C mod it only consumes
5 ma (not sure but I think stock is 2 - 3 ma). That will get a lot of signal into the ground but might change the
Bandito's characteristic of working great in very trashy areas. It's not clear what in the circuit allows this feat.

The negative supply might need addressing too but most changes there will increase current consumption a bit.
I have an idea to make a Golden Saber and use plus and minus 12v on it to see if it makes any difference.

Well here's a schematic with some of the changes for you to peruse;

[Koala]

Found this thread on the mods forum. The Eldorado and Bandido are very similar. Noticed that a performance increase in all metal mode if the board is in a metal grounded case or at least a lined with foil. Link.

Doing some research at the moment to find the best coil specs for a 27DD. Thinks it's better to go for a center tap same as original to keep the phase shift the same.

Tesoro detectors seem to be popular on the www.teknolojiekibi.com forum site some good results with home made Eldorado. Google does not work well on my machine and bings is slow going.

Waiting for parts from China to arrive while this is happening I will finish the Mouser list off and get them ordered.

[kt315]

The Eldorado and Bandido are very similar.

Gold Mountain Tech King Cobra has two tone sound, Accept Reject Notch filter, also you can add Surface Blanking adv like in Royal Sabre tesoro if you want.

good luck

[Silver Dollar]

I think all the Tesoro projects on here use the same coil. The one for TGSL should work on Bandito.
I made a few of them before moving on to the Minelab coils. It's like 100 turns and 105 turns, though,
I found the wire I got off Ebay wasn't really the AWG it was supposed to be so my numbers were off.

To tell you the truth buying a coil will be much cheaper in the long run. I got $12 worth of wire, a $15
case and $32 worth of epoxy. The inductance changes daily too so it's hard to pinpoint just what you made.

I have at least 2 sets of original TGSL coils and 4 or 5 other special winds but none in a housing yet. Center
tapped is the way to go though. I found an ancient GS schematic that showed a center tap. You don't have
to worry about shielding if you center tap. You want to wind it bifilar so get 2 coils of wire to make it easier.
I built a jig with a plate with the coil form on it and a 2x4 with the 2 spools of wire at one end and coil form
at the other. It's easy to wind that way! The front end only makes sense with a center tapped coil.

On grounding the case, originally it was better not to then somehow it changed and everybody was grounding it.
The Tesoro's in the old days were in a metal case, then they switched to plastic, I don't know if there was any
shielding in it. I''l look in the Bandito as soon as it gets here.

[Koala]

Wound some coils for my IDX don't have any problems with stability. Use a jig that epoxies the wire as it's being wound.

Do have a problem with using a space blanket for shielding. works excellent to start with but degrades with time.

Never wound a bifilar something new to learn does not look that hard. (which ends connect to which for the center tap.

Original coils are also graphite shielded as well as center tapped.

Prices in the UK for Tesoro are bad. A silver sabre on ebay just gone through for just under £200 ? Original coils do seem to lack depth also but they do run super stable.

[Silver Dollar]

Hmm I thought in general MD stuff was cheap and plentiful over there. Here prices were very high
but seem to be dropping a bit lately. I just missed a Silver Saber last week. I bid $110 and it sold
for $112!

I'd use mesh screening for a shield but thought it wasn't needed with a center tapped coil?

I found some brass screening that soldered great! Other stuff seems to be plated with pot metal and
is tough to solder to...

If you start with 2 wires and short those 2 together that would be your common ground point. Then wind
the rest of the coil and the 2 ends are your coil points. That way both coils see the exact same voltage
and can eliminate common mode noise.

That epoxying as you wind is the way to go. I wind then tie with dental floss then use superglue to hold them
together but it can make adjusting later a bit difficult. One coil I used tye wraps and superglue then couldn't
get the wraps off! Need a big housing for that coil...

[sled]

Hmm I thought in general MD stuff was cheap and plentiful over there.

unfortunately not, a tesoro silver v2 goes for 500USD (new) in Switzerland/Germany. Problem is that Tesoro prohibits seller from the US to sell to Europe, so prices here are rather high. Luckily there are some black sheep in the US who sell to Europe under the table

Prices are horrible: http://www.abenteuer-schatzsuche.de/...oren:::72.html

[Silver Dollar]

Well my Bandito came in today it's cool! I set it up and air tested a screwdriver to 12" or so.

I was reading that the Bandito found more trash (than the older models) so some were adding 90 degree Disc to it.
So I started working on a possible mod to allow 120 or 90 degree Disc;



I had a thought too about the center tapped coils. If you use the beginning wires for the coil and ground the ending
wires then the outside of coil will be ground so it will have some self shielding...