Remaining issues

[Qiaozhi]

Hi Qiaozi,
Thanks for the latest official baracuda, but i cant find the layout, pcb to print or lay file, i like to test it.

Rips

Like the MiniPulse Plus, the PCB layout files have not been posted, but I will post the Gerber files later.
The PCB database is from Easy-PC, so this would not be useful for most members anyway. Also, the layout is double-sided with plated-through holes, and a ground plane on the bottom layer. This would be an extremely difficult PCB to make yourself at home using nasty chemicals.
Silverdog provides a valuable service to the Geotech community, and I would urge you to purchase a PCB from there.

By the way, I do not receive even one penny for my efforts on this project from any source, and it is provided free-of-charge for your enjoyment.

[ripsdevala]

Hi Qiaozi,
Thanks for the latest official baracuda, but i cant find the layout, pcb to print or lay file, i like to test it.

Rips

[Qiaozhi]

So the bottom line is, do the upgrade if you have one, but pick a different PI if starting from scratch.

Rick

It depends on what you want to use the detector for. If you're looking for a simple PI design to use on the beach, and to search for coins, then the Baracuda is more than adequate. Alternatively, you could build a Surf-PI that does the same job. However, the Surf-PI doesn't have an associated Build Document, and (although it is also a simple design) many electronically-challenged members have had problems. So in that case, the Baracuda would make a good first project.

[rickb]

So the bottom line is, do the upgrade if you have one, but pick a different PI if starting from scratch.

Rick

[Qiaozhi]

Can you at least note what these remaining fundamental issues are?

Rick

The other issues are eluded to within the Build Document, but essentially they are related to the 40106 IC.

The main and Earth field pulse widths are not well matched, so EFE is compromised. Due to component tolerances, the amount of this discrepancy varies between different builds. Also, below about 20us delay, the sample pulse width becomes increasingly smaller (as does the Earth field pulse), but the amount they both decrease is not identical. These are problems that could be resolved by using monostables (in a similar manner to both MiniPulse Plus and Hammerhead) but I didn't want to go down that route, since it would fundamentally change the simplicity of the Baracuda design. So, although these changes would improve the overall operation, it could no longer correctly be called a Baracuda. As I said earlier ... it is what it is.

There are several PI designs available on Geotech, and they all have their strengths and weaknesses. One of the Baracuda's strengths is its simplicity, but it was let down by unreliability due to some poor design. All tests with the Geotech Baracuda REV-A show that unreliability and component failure are now a thing of the past, so you can go ahead in confidence that this detector does actually work. The addition of a Build Document (in the same manner as the MPP) should also help to eliminate some of the more common errors that constructors had with this design. The important thing is to build the design step-by-step, and test each stage as you go. Then you'll have a fighting chance of ending up with a working detector.

Just in case you're wondering why this is Revision A, and not (say) Revision D, is to prevent any confusion between other versions floating around on the internet. Hence why this variant has been renamed to Geotech Baracuda, to distinguish it from other (often unfinished) versions by other people.

[rickb]

From the pdf.

The intention here was to keep the design as close to the original as possible, but to remove the existing design flaws without making major changes. As a consequence, there are still a few fundamental issues that could benefit from a redesign, but that is beyond the scope of this exercise.

Can you at least note what these remaining fundamental issues are?

Rick