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here are the b1 b2 programs
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Looks like a PWM to meComment
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I was having another look at your original small versions of the 'beach' waveform yesterday. It's harder to pick out by eye the different freq. components. The whole cycle repeats in 385 microsecs as before, and there's clearly 3 cycles of 7.8kHz in there. But I was tricked by the fact there are 9 cycles in total in the 385usec, making it look like there should be (3x7.
kHz present too.
Thankfully the spectrum analysis shows 7.8k, 13k, 18.2k and 39k, ratios of 3 : 5 : 7 : 15 ( with some 2.6k sneaking through)
I'm not sure why the 2.6k shows up, but it's unlikely ML make any use of it.
Regarding the PWM idea: I did wonder if the 'field' multi waveform could be generated by simply modulating a 39kHz square-wave with (7.8k + 18.2k) sine waves. It may produce more unwanted/unused frequency components, the sum and difference signals that mixing creates.
If this 'beach' waveform is made by modulating 39kHz, then it's going into 100% modulation, as 6 out of 15 cycles are missing.
I wonder how low (and high) the detectors frequency is capable of good performance? They offer 5kHz as a single frequency ... whether it's on-the-limit, or even beyond-the-limit depends on things like coil nulling. If they could run it down to 4kHz, then there's the possibility of running at half the 'field' frequencies, ie. 3.9k / 9.1k / 19.5k (keeping the same ratio's), which might suit the U.S 'deep silver' niche hunters, though may be good on wet salt beaches, too.Comment
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I was scrutinising those X-rays earlier on, too. I thought there may be a digital pot on the PCB, possibly for nulling the coil. There's obviously a microcontroller on the board (for coil ID & anti-copying protection), so it would add little to the complexity/cost to add an e-pot.
The large inductor suggests a switching power regulator, probably to generate a negative rail. But it could just be power line filtering.Comment
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Interesting X-rays of that coil assembly.
The 'stay' wires inside maybe be 'ground' guards- instead of full shield.
A poster in that link stated NO uP inside. It could be simply an EEPROM. An e-pot might be there also within the same package.Comment
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The 10-pin device is curious, makes me think it's an accelerometer IC, like in the CTX. Though I would have expected the IC die to show up some distinctive features under x-ray.Comment
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Another thing I hadn't realised: the part of the coil housing where the pcb sits is not 'straight' , so the 10-pin device would be sitting at an odd angle relative to the search-coil. You will remember the CTX's accelerometer was fitted onto the pcb at a peculiar angle - everything else was neatly lined up, the acc was twisted 30 degrees. So it may not be an accelerometer.Comment
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It might be what you speculated earlier. A digital pot for nulling? In the images you don't see the typical nulling leads or loose feedback coil. Everything seems neat and in place.Comment
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I was thinking the digital pot would be the 6 pin device next to the row of 4 pads on the edge of the board. They're normally small things, eg. the one inside the Garrett Propointer is a 6-lead SOT-363.
But the 6-pin device could also be a single opamp pre-amp, it would be odd for ML to not use a coil pre-amp.
But it's possible it's a microcontroller, the smallest Microchip PIC parts, the 10F series, are available in a 6-pin package.
All the other parts look basic, like dual-transistors in a 6-pin pack.Comment
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I have been on a few Rallies where people have had the Equinox. Its found no more than the Deus, old Tesoro's or even the Garrett 250
Its more to do with the nut behind the detector, than the detector
Or to put it another way its how well you cover the ground, not how much ground you cover
But then luck also plays its part. Luck does even itself out if you put in the hours.
If you want loads of say Roman then its Location, Location, Location.Comment
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just bring DD57 comment here
Minelab, new series coming called Vanquish..340, 440, 540. models. not underwater units but water resistant and multi freq so wet sand beach compatible, waders... $300 to $500 bucks for a machine with great features. wireless on high end
Nokta Macro-- the SimplEX --- whistles and bells that are desirable and submersible to 10 feet. easy settings easy looking to use. wireless too if want, and up gradable by computer site. $300 to $400 bucks
these are for budget minded serious hunters, easy for a beginner to read and learn, not beginners toys in the big box stores . kind of like a hemi engine without air conditioning in an old muscle car. raw power simplified with a few amenities like leather seats and a stereo. .
these are serious machines. the companies are following market trends with the new tech and smaller packages. power supplies , weight, features, water resistant at least. and $$$$$$$$$ affordable. these could be backups for the higher end units too.
hang in there USA Garrett has a huge following with the AT PRO. but i think this is the price range to target them. First Texas building a monster unit in the making, but what i read price wise it may be for the serious daily beach hunter, although going head to head with other high end units.. be like a good old time Nascar race ... thier engineers are the best.
i did see on ebay some choice machines listed... a Richard Ray unit, some of Paul's oldie favorites too.. and some good solid machines with no bids. used machines going for a song or simply not selling except for a few. The Whites IDX commanding good prices, Deus, ctx3030's. Gold Bugs..... J W Fishers... but also a ebay full of them that nobody wants... old 1970's heavy battery hogs with old capacitors deteriorated, hard to use. once state of the art must have now nostalgia except for a handfull of diehards. and no bids.Comment
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ML is going wild:
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