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  1. The short extension at the elbow-cup is light, it's three-piece construction - the tube is 50 thou ( 1.25mm ) wall-thickness, the joiner is short and large-bore, the end-cap is thin and hollowed-out. There's no plastic plug, obviously. The middle-rod extender is somewhat over-engineered. The walls are 2mm thick at the insertion sections, meaning they're 3mm thick over the central 33mm length. So I could've bored it to 1.5mm, and had shorter insertion overlaps. The 33mm length could've been 8mm shorter if I'd simply moved the spring-pip 12mm, but aesthetically the under-inserted rod would
  2. On the current Eqx, the pip-locating holes on the middle shaft are spaced 40mm apart, which I think is too far, and a spacing of about 30mm would be better if the new machines share this shaft style.
  3. In the thread about possible design improvements for the Equinox series, I said the breakdown of the three-piece shaft could be improved. It currently has two reasonably short upper parts, and one excessively long lower rod. To improve packing, the upper rods need to be a bit longer, and the lower rod shortened. Having done this exercise on my Fisher F75 shaft, I turned my design ideas to the Eqx. The upper rod obviously has the 'height', due to the control pod and lower stand, and this limits the compactness to 28cm / 11" in that direction. This is slightly larger than the coil, which
  4. Nearly all commercially available VLF machines are 'motion mode' in operation , except when in 'pinpoint mode'. A few have a 'permanent pinpoint mode' as a feature, such as the Fisher F75. One manufacturer that still makes a range of true non-motion machines is C-Scope in the United Kingdom, the CS1220XD is the flagship of the models: https://www.csmetaldetectors.com/shop/category/non-motion-metal-detectors
  5. Geotech1 seem to get spammer problems, but their security methods to tackle it made it tougher to register for everyone else. There is this page that may help: https://www.geotech1.com/forums/showthread.php?24472
  6. @Longbow62: Should we assume you're using the stock 11" coil ? Do you have the large coil ? Have you considered buying one?
  7. As an electronics engineer, I have to say your project is very neat and well planned. Are you a member of Carl & George's "Geotech1 Forum" ? It's a useful resource, if nothing else, and there's always the angry Lithuanian/Bulgarian/ etc guys to keep the place entertaining. Re: the coil. I would advise designing your machine to work with a known good commercial coil, then when you're confident it's working OK, consider making your own coil. Your chances of success are much improved that way.
  8. Here's the BBC's version of the story: https://www.bbc.co.uk/news/uk-wales-46179570 Every one of those old-time miners is named Dai ...[humour] It is possible to pan the rivers for gold, but I'm sure it's just flecks, not detectable stuff. But even that can land you in trouble: https://www.theguardian.com/uk-news/2018/may/10/police-investigate-gold-panning-welsh-river
  9. I assume there's three 18650's in parallel, so if the best available types with 3400 mAh capacity are used, that's 10200 mAh , which is about double the nominal 5000 mAh capacity of the 26650 size. Even if more modest 2400 mAh cells were used, that's still 7200 mAh, with estimated 19 hours run-time.
  10. I would leave it 'original-looking' if it was mine, just stick to internal tinkering. Isn't there a mod that adds 20 batteries to boost TX output? That one sounds like a good use for modern Lithium cells.
  11. I assume that's Sven in the red top? I notice that machine has 3 additional pots on it. Do you have any plans to modify and improve your machine ?
  12. An interesting question, BigSky Guy. The 8-pin coil connector only uses 7 pins, there's a spare. And the 0 Volt/ground of the USB port appears to be connected to one of the coil pins ( transmit cold ). So in principle, the spare pin could connect to the 5 Volt of the USB port. That then allows you to charge the battery through the coil connector. However, it's worth noting he's used an 8-pin connector for the audio output, even though it only needs 3 pins .... so perhaps he's simply wired all 4 USB pins to that connector ( and just leaving one spare pin )
  13. Quote: "I think (could be wrong...) a rough rule-of-thumb is that an opening in a conductive shield should be smaller than the wavelength of the incident wave in order to be effective. A 2.4 GHz EM wave has a wavelength of 125 mm." Unfortunately not. The rule-of-thumb I use is to keep the aperture size below 0.1 wavelength, but the experts seem to prefer even smaller sizes. There's a reason microwave ovens have very small holes in the window screen. Here's one online guide, (though they are manufacturers of screening products, so are naturally going to encourage people to be thorough )
  14. My test location was going to be near a radio tower, that's bristling with directional microwave antennae, probably 5 GHz and up, but may well have lower freq cellphone gear on it, 800 MHz & up. It drives my Fisher F75 mad, I found that positioning myself so my body was between the tower and the control-box, made a significant improvement. The sight of me walking backwards across the field would no doubt have left observant onlookers puzzled. But they would probably assume I'm wierd simply for metal detecting ... so it may just be dismissed as 'fruitcake behaviour' . Adding a foil 'hat' to
  15. Quote: "First Texas used EMI paint on the T2/F75 connected to ground to help although there are far better technologies now where they can incorporate conductive fibres when moulding the part. T2/F75 etc coils are moulded from conductive plastic. But there's shielding and there's shielding. A terrific shield is not desirable on a coil, as it stops it picking up metal objects. On the control box, anything from solid metal to low-resistance graphite is useful. The huge weak point in the T2 control-box shield is the massive hole in one side where the LCD is. There are ways of making a see-t
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