Baracuda PI Air Test

[plumabob]

I'm done messin around with this Baracuda PI 12.5 inch coil .448uH 1.2R. Here is a short vid. Quarter, nickel, size 8 gold ring and a tungston ring were used for the testing. There is some in house electrical interference, in actual field use depth is improved by 2-3 inches on the smaller targets. Sensitivity is pretty good too. It picks up a nickel I clipped into quarter sized pieces at 5-6 inches.

This was a great Silverdog project. I highly recommend a baracuda kit to all.

http://www.youtube.com/watch?feature...&v=cFkDo4nM3rY

[Koala]

Very impressive well done

[mohandes]

I'm done messin around with this Baracuda PI 12.5 inch coil .448uH 1.2R. Here is a short vid. Quarter, nickel, size 8 gold ring and a tungston ring were used for the testing. There is some in house electrical interference, in actual field use depth is improved by 2-3 inches on the smaller targets. Sensitivity is pretty good too. It picks up a nickel I clipped into quarter sized pieces at 5-6 inches.

This was a great Silverdog project. I highly recommend a baracuda kit to all.

http://www.youtube.com/watch?feature...&v=cFkDo4nM3rY

your depth is very nice
can you put here pic of your pcb and your partlist(for transistors and your coil detail)

[SVEN1]

Very nice, my two Silverdog PCB builds suck, about 7" on a gold ring with 9640. With 454uh 10.5" coil
With tip 127, doesn't work properly.
Both built using parts list to match Silverdog PCB.

What parts did you use?

[Koala]

Mmmmmm I am interested to in what parts and coil. Seem to be two outcomes. Some build the Baracuda and it's superb and some build it and it sucks. I am building one at the moment and any pointers would be appreciated.

SVEN1 is your detection poor on other metals also.

[dfbowers]

Sven, Try a 300uH coil and check your coil damping with a scope. That's the only difference between now and when I tested it. You should be getting closer to 10 or 11" with the 9640!!! If not I will send you the coil I was testing with.
Don

[SVEN1]

Sven, Try a 300uH coil and check your coil damping with a scope. That's the only difference between now and when I tested it. You should be getting closer to 10 or 11" with the 9640!!! If not I will send you the coil I was testing with.
Don

Hi Don,
Also tried my PI 300uh coils, 5-7-9.5-10.5, no improvement.
Might be the coils, 19 strand teflon wire, 24AWG.
Haven't given up on the Cudas, yet. I have these two little enclosures that I want to use up and the Cudas fit in there very nicely.
Will make a coil using magnet wire as you suggested in your PM.

Kola,
Yes all metals across the board.
My coils are fast built for my PI that gives best performance, which may not be ideal. Don said got the
10-11", with my PCB, going to assume its my coils.

[plumabob]

I settled on a lm358 in place of the lf412 and ended up with the 9640 instead of the tip126 as mentioned above. Other then that all the rest of the components are what Silverdog supplied with the exception of some of the pots. The coil was built a long time ago. I build many coils so I can't say for certain what wire was used. But it is properly shielded and damped. I would also agree that a well made coil is critical for any decent performance. Apparently there are a lot of variables with the coil. Don gets good performance with a 300uh coil, mine works best with a .448uh coil. The original factory barracuda used a .545uh coil at 1.24ohms on the 8 inch coil.

Regards,

Bob

[mohandes]

Sven, Try a 300uH coil and check your coil damping with a scope. That's the only difference between now and when I tested it. You should be getting closer to 10 or 11" with the 9640!!! If not I will send you the coil I was testing with.
Don

hi Don
i find you here!i test this detector whit diff oils and pot 1k to find best R.
so depth very bad but i dont test it by coil 300mkh .
mr Don i build CC coil but dont work well can you explain me (teach means) , i make it for IDX
regards

[SVEN1]

Tried a few coil winds
9.5" coil 27 turns 22AWG magnet wire 546uh, just making a solid target sound at 7 1/2-8" on a gold wedding band, after 8", signal is broken up to 9" the no signal.

Was going to wind up another 10.5" coil 21 turns to get me around 300uh but, had only enough to wind up
a 27 turn 7.5" coil 22 AWG magnet wire 324uh, same result air test results as the 9.5"

Don was using 20AWG wire, maybe that will also make a difference.
Right now out of magnet wire, will have to wait until I can get some 20AWG.

Air testing results 7.5" coil, solid target signal
A small silver half dime comes in to around 4-5"
Other larger coins to about 7"
Small gold ring to about 4", one next to the larger wedding band

So the Cuda is very usable with the 7.5" coil at this point.
Will work on it some more over the next few months to achieve better depths.

[mohandes]

Tried a few coil winds
9.5" coil 27 turns 22AWG magnet wire 546uh, just making a solid target sound at 7 1/2-8" on a gold wedding band, after 8", signal is broken up to 9" the no signal.

Was going to wind up another 10.5" coil 21 turns to get me around 300uh but, had only enough to wind up
a 27 turn 7.5" coil 22 AWG magnet wire 324uh, same result air test results as the 9.5"

Don was using 20AWG wire, maybe that will also make a difference.
Right now out of magnet wire, will have to wait until I can get some 20AWG.

Air testing results 7.5" coil, solid target signal
A small silver half dime comes in to around 4-5"
Other larger coins to about 7"
Small gold ring to about 4", one next to the larger wedding band

So the Cuda is very usable with the 7.5" coil at this point.
Will work on it some more over the next few months to achieve better depths.

[ATTACH]27040[/ATTACH]

please say ne about your transistors, my means for example you use mps or bc517 and ...

[SVEN1]

MPS

[Koala]

I settled on a lm358 in place of the lf412 and ended up with the 9640 instead of the tip126 as mentioned above. Other then that all the rest of the components are what Silverdog supplied with the exception of some of the pots. The coil was built a long time ago. I build many coils so I can't say for certain what wire was used. But it is properly shielded and damped. I would also agree that a well made coil is critical for any decent performance. Apparently there are a lot of variables with the coil. Don gets good performance with a 300uh coil, mine works best with a .448uh coil. The original factory barracuda used a .545uh coil at 1.24ohms on the 8 inch coil.

Regards,

Bob

Hi Bob,

Trying to work out a parts list for ordering. and need a little help.

Q3 and Q4 did you use a matched pair.

In real use is it worth putting the delay on the outside or could it be left on the board. (is it a set once and leave alone)

Can't tell tell from the photo did you use a 6900uF as per original spec or a 4700uF as per silverdog for C1.

Can't see the coil damping resistor as it's hidden behind a heat sink. How many Watts are required? and is that the only one that required to be above 1/4 Watt

Cheers

[plumabob]

Matched set of 2n5485's
4700uh on the C1
I like mine on the outside for field adjustments.
Damping resistor is probably a 1/4 watt, I can't get to it as it's under heat shrink.

Regards

[Koala]

Matched set of 2n5485's
4700uh on the C1
I like mine on the outside for field adjustments.
Damping resistor is probably a 1/4 watt, I can't get to it as it's under heat shrink.

Regards

Thanks

That is a big help Will get everything ordered now. Was tying to understand why some preform so badly and some so good. Those that preform badly don't seem to work with any coil yet those the work will seem to work with a lot of coils.

Suspect it could be a mismatch Q3 and Q4 and surrounding components. if you have worse case resistors and worse case Q3 and Q4 then the errors will mount up to quite a lot.

Here's hoping I end up with a and not a

Thanks again