Geotech

The wireless pinpointer connect was something that the White's TRX had designed into it, but it was never implemented. I even filed a patent application on the technique about 4 years ago. Because the V3 wireless module was going obsolete, everything was designed around a new module that was supposed to have debuted with the first new 'Sport design. The pinpointer would tell the detector to disable its transmitter, and pinpointer audio would be sent to the headphones. Since the TRX is a full VLF design, it could even send VDI info to be displayed on the detector screen. User setting changes could be made from the detector or a cell phone app. However, White's mgmt didn't think much of the idea from the beginning*, it was entirely driven by Engineering. After I left they let the patent app expire, and apparently even wireless audio got dropped from the MX Sport. As far as I know, the socket for the wireless module is still being put in the TRX. It was intended that early pinpointers could easily be upgraded to wireless, I'm guessing something that will never happen. - Carl * The verbatim quote: "I don't like that idea at all." That was the day I first asked myself, "Why am I here?"

It works, I've done it. The ink used in paper money has iron in it, any good BFO will detect it but only an inch or so away.

If I don't get back within a year, then a follow-up is probably in order. Send me your email, I'll set you up right away. carl@geotech1.com

All ya have to do is read the "Can't Register?" post. It tells you why, and how.

Yep, Geotech ain't much different than the rest of the internet, but it is interesting. Lots of good ideas pop up from time to time, very few ever get developed into something usable. A lot of the guys don't have the complete know-how, or don't have the time, to get it to the end. This feeds back into MD's "kickstarter" thread, where the kind of people needed to turn a metal detector idea into a metal detector are people who have done it before and know all the nuances and gotchas of what it takes to get to the end. The people who say they can do it are plentiful, the people who can do it are exceptionally rare. As for Funfinder's thread, I think his frustration is that people on Geotech have been build plain ol' PI detectors for, what, 16 years now? And there doesn't seem to be much forward progress in what they've done. I would agree with that. I think he'd like to see more VLF and multifrequency developments. But, compared to PI, those are really hard for DIY folks, so most of them stick with simple PI circuits. I get his frustration.

I'm gonna see if mgmt will allow a better tour video. Certainly there are some things that we don't want to show, but there is a lot of impressive stuff in the factory that is not sensitive. Having worked at White's and toured Garrett & Tesoro, I can say that FTP easily has the most advanced factory in the business, and probably the biggest.

I've been on both sides of this coin, as an independent developer trying to work with other independent developers, and a detector company employee trying to work with independent developers. It's often said that trying to manage engineers is like herding cats; trying to manage independent engineers is like trying to herd birds. It mostly doesn't work out well at all.

Even though it looks like a mono, I think the Infinium coil has separate TX & RX windings.

Last week when the Xventure first hit eBay, there was only one for sale, it was available nowhere else, and wasn't even mentioned on the White's web site. I see they've now sold 2 on eBay, it's now on Amazon but listed as "unavailable," and still nothing on the web site. This has to be the most bizarre detector intro I've ever seen. It reminds me of when they put the BeachHunter ID on sale; it wasn't finished, so they couldn't actually sell any, but they had to advertise it "for sale" to satisfy contractural obligations.

Odd marketing strategy, selling one-a-week on eBay. Somewhere, 2 kids will be unwrapping a new Xventure detector on Christmas.

Bob, Reg was very closely involved in the SL development. The reason the SL is so quiet is because of Reg's work.

Tom, I'm in the valley every month, I live in Junction City. I even do field testing up Quartzville Creek, so I drive right by White's on the way. Next time I'm out that way I'll give you a yell.

I have a soft spot for the TDI-SL since it was my baby. Originally I had plans for taking it further, and if you look closely at the PCB you will see those plans. But the reality is, that platform has pretty much reached its limit, which is why I was spending all my efforts developing a whole new platform. Unfortunately, White's made some choices that killed the whole thing. Reducing the delay to 8us is easy-peasy. Getting it to work is not. Getting it to work in a way that's manufacturable is even worse. If you measure carefully, you will even notice that the 10us setting on the TDI is actually closer to 11us. If a lower delay was easily doable on the SL, it woulda been done. The reality is that the SL is fast approaching its EOL. There are new competitors on the horizon that will absolutely run rings around the TDI. If not the QED (and I'm as big a skeptic as anyone) then there are others. In the end, the only way to keep it alive will be to lower the price to $599, with free shipping. All this said, I whole-heartily encourage you to spend a lot of time & effort trying to improve the SL.

Garrett had a TM on the name "Treasure Vision" which refers to their GTI display. However, a Chinese detector called the "Treasure Vision" was already being sold in the US and Garrett was not enforcing their TM in that case. And, unlike patents, if you don't enforce a trademark ALL THE TIME you lose the right to enforce it at all. So White's could have dismissed their complaint, but chose to avoid a conflict.

The patent in question is US7310586, which covers wired and wireless data transfer (no, I'm not speculating, yes, I have the docket). It's the same patent they sued White's over when I was working there. I found prior art that would invalidate the patent but White's decided to settle instead.

Here's what I have: Pin2: Orange Pin3: Orange-shield (also connected to strain relief) Pin4: Green Pin5: Green-shield Pin1: no connect

I haven't looked at this patent so I have no opinion on it one way or the other, but I'd bet heavily that it gets approved. The US Patent Office, and the patent process in general, is widely recognized as thoroughly and utterly broken. USPTO is so overwhelmed and understaffed that most applications get only a few hours of examination; approval doesn't mean the patent has merit, and I'd guess that over half of all patents have little or no merit. Minelab is well-known to have patents on already-existing techniques, such as Litz coils and Eric Foster's ground subtraction method. They're gaming a broken system.

Karbowski was literally making them in his barn. When he died, Jimmy Normandi got all the remnants and had Roy Van Epps (the last surviving entity of the old Discovery Electronics) building them at the Discovery Ghost Factory. Roy made enough off Bigfeet to occasionally buy dinner.

Here's a little back-of-the-envelope figuring... Let's say the Bigfoot in active production can't justify a $500 price tag. Maybe $375 MSRP for a typical $300 street price. Let's say the manufacturer sells wholesale at 60% MSRP, that's $225 which would give a dealer $75 mark-up to street. The manufacturing costs for this coil will push $100, so the manufacturer makes $125 per coil. They average 10/month, so this comes up to $15,000 per year. Not really worth the effort to develop and tool up for such a coil. Now you'll say, "I'll bet the market is a lot higher than 10/month!" Maybe, maybe not. I knew the last guy who was hand-building Bigfoot coils, and 10/month was about right. And, to make matters worse, half of those he built didn't work, so he built 20 to sell 10. This would be an opportunity for an entrepreneur to step in and develop a family of Bigfeet coils, not just for White's but Tesoro, Fisher, Garrett, etc. Then your market really opens up, and makes sunk development costs more palatable. But it would still be a one-man band, not enough money to be made to hire any help.

There are 2 interference mechanisms that people are mixing in to the discussion. One is operational interference, where the active signal created by the PP couples into the main detector. Same issue people have when trying to run detectors in close proximity. It doesn't matter what the nominal frequencies are. A 12kHz PP can interfere with a 56kHz Racer. Harmonics can couple directly in and intermods can get generated that fall in-band. But because of variations in both the PP and the detector operating frequencies, along with the narrow bandwidth of the detector's baseband (typically 10-20 Hz), it will happen with some people but not others. Most of the time, the odds are in your favor. The second problem is that of inductive ringing, whereby bringing a closed coil of wire close to a detector coil will cause the detector to couple with the coil. This isn't so noticeable in a VLF detector, but in a PI detector it causes the flyback to ring. Even when a pinpointer is turned off the coil usually has a cap across it, so it can still ring (even more so, because it's resonated). The Minelab PP disconnects (opens) the coil at turn-off so it won't do this.

I'm the "Carl" half of Geotech... the Sea Hunter coil would probably work just fine. I use a Garrett XL500 PI coil on my Hammerhead design and it does nicely in the water.

Pinpointer interference is hit-or-miss. All detectors, including pinpointers, have manufacturing variance in their operating frequencies. In your experience the Minelab interfered with the Racer; someone else would say they work just fine together. The short of it is, you're unlikely to get a correct answer.

GB, on a whim I tried the Garrett BFO coil on my TDI. It's a dual 5+12, the 12" reads 120uH and the 5" reads 140uH. Each coil can be run individually as long as the idle coil is dampened to keep it from ringing. Sensitivity is poor, 4-5 inches on a nickel, but I did not re-dampen the active coil, and I'm sure it's overdamped and reducing the sensitivity. Furthermore, the ~3 ohms of coil resistance is limiting the turn-on current; the TDI has an internal 2 ohm series R that could be shorted to compensate for this, but the SL has no such resistor. So the short of it is, yes, it will work. And with some tweaking, it may work OK. But those tweaks will likely make the stock coils not work, unless you add a way to switch the damping R. Also, running the Garrett coils in series could also work, but would require each coil to be dampened to get to an overall good decay. And then, the 6 ohms of coil resistance will be a problem you can't solve.

The TDI should be just fine driving 180uH. If you want to play it safe, put a few ohms in series with it to start with. And, as I said, it'll need a different damping resistor, the TDI has 680 ohms which will probably end up too low.

I also looked at this many years ago when I did the Hammerhead design, I wanted a dirt-cheap coil that's easy to get, and there are a billion of those old Garrett BFOs still around. From my notes, the Garrett BFO coils have about 120uH inductance and 3 ohms of resistance. The TDI prefers 300uH and less resistance, maybe an ohm or so. I decided not to use the Garrett coil for Hammerhead but don't remember why, it woulda/coulda worked. It also would probably work on the TDI, in that the likelihood of damage is pretty nil, but I have no idea how it would work. Certainly the damping resistor would need modification. Lower inductance will increase the TX field but weaken the RX sensitivity, and higher R will weaken the TX field. Addendum: As I think about this some more, it seems like I may have stuck that huge 24" square Garrett BFO coil on a TDI. I was looking for a way to find my silver test cache. I must have been disappointed in the results because I wound my own 24" coil.