SMT Bandito Info/Build

[Silver Dollar]

We it seems (from doing a little reading) that the negative supply can work fine down to 2.5V.
A side benefit is low current consumption 14 ma vs 36 ma for a TGSL with approx. 5V. That's
nice! I wonder if we could go to +- 2.5V and super low currents?

It looks like we are a bit late to the party as most of the work on these was happening a few
years back. Too bad I'd love to get a few more boards and possibly do a IGSL style Bandito
using 2 pcb's. We have the sprint files but just a viewer so can't get the gerber files....

[Koala]

Back from a day at the beach with the IDX. Had a good day plenty of finds. Kinda got it dialed in now

Will have a hunt around for a supplier that stocks most of the components. Metal film resistors and film capacitors aren't that common most are chip technology

I am normally late but not by years.

Yep that's a very nice bonus means 1x PP3 will give useful detecting hours vs the weight of 8x AAs it never dawned on me.

[Koala]

The only resistors I can find in a good range of values are classed as
Chip?
Thick film
Thin film

Quoting the wiki

"The resistance of both thin and thick film resistors after manufacture is not highly accurate; they are usually trimmed to an accurate value by abrasive or laser trimming. Thin film resistors are usually specified with tolerances of 0.1, 0.2, 0.5, or 1%, and with temperature coefficients of 5 to 25 ppm/K. They also have much lower noise levels, on the level of 10–100 times less than thick film resistors."

So I take it thin film 1206 is what is required

[Silver Dollar]

Yes the thins are close tolerance and low drift. Now caps on the other hand...

It seems ceramic is OK for all of the SMT caps. If you notice the TX and RX caps are through hole.

Have you tried to find the chips yet? I ordered from Mouser a little while ago and found good prices and
a great selection. They even have a hobbyist shipping plan for $5.

I found a way to get the gerbers so I can have some more boards made. Anybody need a board?
I estimate $6 delivered. I may try to make a few slight changes, mostly to allow for a Dual Band ito.
It should be just a few extra holes for wires easily ignored. The Minelab TX should be added too if it
will fit and maybe a few regulator choices to allow for different power schemes?

[Koala]

there are at least 11 none surface mount capacitors mostly the larger sizes.

Quite a few different sizes of resistors

Farnell have every size in 1206 but in packs of 10

1x 20
1x 100
2x 150
1x 200
6x 1K
1x 1.2K
2x 2.2K
2x 4.7K
5x 5.1K
8x 10K
1x 12K
8x 20K
1x 27K
4x 47K
1x 82K
10x 100K
1x 150K
5x 200K
1x 430K
1x 470K
2x 620K
4x 1M
2x 2.7M

R65-??

[Koala]

Cheers mouser looks good slightly dearer but supply individually I can look up the part numbers and post here silly both doing the same thing

Used mouser before only place I could get a Whites coil connector.

[Silver Dollar]

Well the electrolytics are through hole too but I have those so wasn't too worried about it.
Someone said you can buy an assortment of SMT resistors from China. I got some 1%
through holes a short time ago $6 for 600 resistors, a good deal I thought. I need to find a
deal like that on caps. My old junk box is getting pretty low these days.

[Koala]

Well the electrolytics are through hole too but I have those so wasn't too worried about it.
Someone said you can buy an assortment of SMT resistors from China. I got some 1%
through holes a short time ago $6 for 600 resistors, a good deal I thought. I need to find a
deal like that on caps. My old junk box is getting pretty low these days.

Had a look at some of the SMT resistor kits very little in the descriptions but tolerance are either 1% or 5% so guessing they are thick film

http://www.ebay.co.uk/itm/0805-SMD-S...item2c80bcf573

I will stick to plan A and start getting part numbers for Mouser if something better comes along it no big loss

[Koala]

using thin film comes out very expensive £19.61 just for the resistors

1x 20 660-RN732BTTD20R0B25
1x 100 660-RN732BTTD1000B25
2x 150 660-RN732BTTD1500B25
1x 200 660-RN732BTTD2000B25
6x 1K 660-RN732BTTD1001B25
1x 1.2K 71-TNPW12061K20BEEN
2x 2.2K 71-TNPW12062K20BEEN
2x 4.7K 71-TNPW12064K70BEEA
5x 5.1K 754-RG3216P-5101-BT5
8x 10K 756-PCF1206R-10KBT1
1x 12K 71-TNPW120612K0BEEA
8x 20K 756-PCF1206R-20KBT1
1x 27K 754-RG3216P-2702-BT5
4x 47K 754-RG3216P-4702-BT5
1x 82K 667-ERA-8AEB823V
10x 100K 756-PCF1206R-100KBT1
1x 150K 756-PCF1206R-150KBT1
5x 200K 660-RN732BTTD2003B25
1x 430K 667-ERA-8AEB434V
1x 470K 754-RG3216P-4703-BT5
2x 620K 71-CRCW1206J-620K-E3 thick flim
4x 1M 660-RN732BTTD1004B25
2x 2.7M 71-CRCW12062M70FKEA thick film

might have to go for plan B there is no plan B

[Silver Dollar]

Yes I had a look on Ebay and came to the same conclusion around $20 for the required kit
to have all the values you need (and hope you don't need more than 10 of each).

Hmm these should be dirt cheap. The problem is handling. 100 should be the same cost
as 10 just the cost to package and ship adds up.

This is the closest I can get $12 for 90% of them.

http://www.ebay.com/itm/1206-5-SMD-S...item5d49493178 Oops 5%!

You might want to make sure you need all those values as I thought I checked and you don't need 430K.
There are 3 schematics floating around. I'm still working on a perfect list...

I'm using 4.99K for the 4.7K and 5.1K and have a mod to the 620K's so can make them 680K or 1M. I have a few
old boards hanging around I can steal parts from and can get most of the oneses from work but it's still a problem.

[Koala]

http://www.taydaelectronics.com/resi...tors/0805.html

1/8W 1% 0805 SMD Chip Resistors only $0.01 min order of 10.
will be thick film though

Keep finding thin film 1206 for around $0.07 available individually but only in one or two sizes. Someone must have a full range ?

would be easy if you need 5000 of each as most only supply on a reel.

[Silver Dollar]

Ya Mouser has some for $0.07, those are 1% and $0.01 nice! 0805 though I wonder if they would work?
I wonder how the guys in china get 5% parts? Maybe they are 1% that don't meet spec?

A lot of people have built SMT boards where did they get the components?

These guys have 1% for $0.10 you could get all 70 needed for $7 but probably $10 for shipping...
http://www.electron.com/resistors/sm...ors-size-1206/

[Koala]

Ya Mouser has some for $0.07, those are 1% and $0.01 nice! 0805 though I wonder if they would work?
I wonder how the guys in china get 5% parts? Maybe they are 1% that don't meet spec?

A lot of people have built SMT boards where did they get the components?

These guys have 1% for $0.10 you could get all 70 needed for $7 but probably $10 for shipping...
http://www.electron.com/resistors/sm...ors-size-1206/

Nice does not mention if they are thick or thin film

Digi-key have some thin film 1% at $.09 here not checked if they have every size have to go out now

[Silver Dollar]

0805's seem to be more prevalent. I think they might work as this show they are close in size;

1206 3.0x1.5
0805 2.0x1.3

Ebay has a wider selection of these...

I have some pcb's and some of each type I'll take a look and see if it's workable...

[Silver Dollar]

Well it looks like you can use 0805's in a board designed for 1206's. They are a bit more
available and a little cheaper. So maybe an option?