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Jim in Idaho

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About Jim in Idaho

  • Rank
    Copper Contributor

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  • Gender
  • Location:
    Blackfoot, Idaho
  • Interests:
    Prospecting, machining, equipment design/build, predator hunting, flyfishing
  • Gear Used:
    Whites GM24K, GMT, TDI-SL, DFX. Homebuilt mineral jigs/with auto-feeder, for gems. Designer & inventor & operator of patented "Sweep Jig' (US10159988 B1), Polaris 4 x4 ATV

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  1. The tests I posted were from a guy that goes by <karelian65> on one Australian prospecting forum. You can follow the thread at this link. Quite a bit of info on prospecting with the TDI series. TDI thread Jim
  2. The tests on various coils, I posted, were not done by me. A prospector from Australia posted them on a forum, and I saved the tests for my own use. I reposted them here. I wish I had his name, but I don't. He did a great job on these tests and deserves any credit. Jim
  3. If you can find one, Mark, from the testing I've seen, the one you want is the NF Sadie 8 x6. I bought a used one, and really like it. very solid, very light, very sensitive. In my testing, it surpassed both the MJ 5 x 9, and the factory 7 1/2DF. Here's a test on 1 grain gold ingot, and I/2 gram gold coin: Jim
  4. That's an interesting question, but I have no idea if that's the case with the Whites TDI SL. Jim
  5. It would be a help if the testers posted the year their SL's were built, along with the battery voltage at the time of the test. Jim
  6. I picked up one good thing about this discussion, besides the overall stuff. That is, there's a benefit to running the frequency maxed out, as far as energy to the coil goes. I'll be doing that from now on, assuming it doesn't cause an excess noise problem. On mine, that's over an 8% gain in coil voltage. Nothing to sneer at. Jim
  7. Sorry, John. I thought you'd said '14. So, it's possible the '13's are different somehow.
  8. Sure looks that way, Mark. John (auminesweeper), and I both have machines built fairly early, and we get very similar results. His was built in '14, and mine in '13. So it looks like yours is different, for sure. What did you have a for a batterry voltage in that test? Jim
  9. I'm measuring mine with a digital multimeter set on A/C volts. On the frequency, I'm seeing, with the 14.5v pack, 6.05v on the low, and 6.54 on the high. MIddle was 6.29. I'd be surprised if your coils have much difference in inductance, but it's possible. EDIT: I just did the inductance test on the 12"DF and got the exact same reading of 1.4 microhenrys. I assume that is the design inductance for the coils for TDI's. and probably the other brands of PI's. But, I don't know this to be fact. Jim
  10. I just tested the voltage output on mine, and it tracks perfectly with the battery pack voltage. With the 4 cell pack at 14.53v, I got 6.29v of output to the coil, and with the 3cell pack at 12.03v, I got 5.3v of output. So the higher battery voltage does push more current through the coil on mine. Thus a stronger magnetic pulse going into the ground. I figured out the correct terminals by using my inductance meter to see which terminals showed a coil across them. Looking at the connector, with the gap at the bottom, the correct terminals are the second from the left, and the second from the right. Inductance on both the NF Sadie 8 x 6, and the Super Pulse 350 14 x 9 showed 1.4 micro-henrys. Jim
  11. With the 12"DF, and 16.8 v battery, mine will easily see a 1 grain gold bar at 3" in an air test, John. Might do even better with my NF 8x6 Sadie, but I haven't tested that coil. Jim
  12. I think, to use a voltmeter, you'd have to put a capacitor across the connections to get a true reading. I'm not sure about the capacitance needed...maybe 5mfd? Jim
  13. I've never checked mine, but find that interesting. Mine was built in '13. Do you have a diagram for the coil connector? I'd like to check mine. Something's fishy, for sure, as the voltage clearly makes a big difference. It's possible, because the voltage pulses at 100kh, that you can't read the voltage difference, except with a synchroscope, or other similar device. Jim
  14. Yeah...mine is a little more sensitive. But, it depends on the battery pack voltage. With the NiMH pack in mine, at 10.7volts, I was getting about 13.75" on the nickel, but with the fully charged Li-ion at 12.6 volts, I was getting 14.5, and with the 16.8v li-ion, I was getting 16.5". All these with the 12"DF. With that coil, the battery voltage is the difference, Mark. And, I gained about 1/2" by turning the GB on, but set at zero. By maxing the GB, I gained an additional 1/2". Jim
  15. John, I couldn't agree more. I'd be happy with a TDI SL that ran from a 21v 5-cell Li-ion battery pack. Maybe with Reg Sniff's filter capacitor modification to ice the cake! Combine that with a Nugget Finder 12" round, spiral wound coil and you'd have a lightweight, really capable PI. Jim
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