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White's Electronics TDI High Q


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2 hours ago, Jim in Idaho said:

Note they said the Auto-Tune was "slow motion".

“They” is me... I wrote up that spec sheet based on my involvement in the orIginal TDI project from day one. Before day one actually. :smile: Anyway, all motion detectors have an optimum sweep speed unless it’s adjustable, as in the White’s V/SAT control. Simply bury a target and sweep over it to find the best sweep speed. There is too fast and too slow and “just right”. A lot of modern VLF detectors do best at a pretty fast clip and people actually hurt themselves slowing down too much. But again, specs are just an indicator, only actually testing your machine will give you a feel for the proper sweep speed. Some machines are forgiving in this regard and some very picky. Knowing this is another thing that gives an operator that magic edge. The TDI in general benefits from “low and slow”.

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I didn't realize you wrote that, Steve. But I am glad a I did the sweep speed mod to mine. I have to sweep a bit faster, but that's no big deal. I prefer that to having to sweep really slow to detect the small stuff. It's possible the C56 & diode mod helps in that regard...making the SL more sensitive.

Jim

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Thinking about the sweep speed. it would be nice, on the SL, to have a small bit of circuitry to allow the filtering to be adjusted on the fly. Something to allow the capacitance in the filter to be changed...even a 3 -position switch would be great. I'm going to be thinking about that this winter....which, according to the weatherman, is going to start this afternoon. Supposed to be 16 in the morning, with light snow on the ground.

Jim

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1 hour ago, Jim in Idaho said:

Thinking about the sweep speed. it would be nice, on the SL, to have a small bit of circuitry to allow the filtering to be adjusted on the fly. Something to allow the capacitance in the filter to be changed...even a 3 -position switch would be great.

Great idea! 👍

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Better for what? Finding small gold? No way. Handling difficult ground and hot rocks? That is what a PI is for more than anything else. In moderate to low mineral conditions with few or no hot rocks you are better off with a VLF and since this is the White’s forum 24K or GMT. If those machines are having fits due to the ground or the hot rocks, then you switch to a PI like the TDI. My little saying is “use a VLF when you can and a PI when you have to”. :smile:

People talk about finding small gold with a PI like the TDI but it’s all relative. Compared to the 24K the TDI is relatively blind to tiny gold and wiry, spongy gold. For my northern Nevada low mineral, small gold locations I prefer the 24K to the TDI.

PI detectors, since they ignore the ground far better than a VLF, have an inherent ability to run much larger coils than a VLF. In bad ground a large coil on a VLF is actually counterproductive, since ground feedback overwhelms and negates any hoped for depth advantage. That’s why you rarely see coils larger than about 14” employed on VLF detectors.

Since PI detectors are far less subject to ground issues they can run much larger coils effectively, making them superior at finding larger items at greater depths. It is not unusual to see 18” coils on PI detectors and coils up to 36” are employed regularly by some users.

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  • 2 weeks later...
On 10/9/2019 at 1:28 PM, Jim in Idaho said:

Thinking about the sweep speed. it would be nice, on the SL, to have a small bit of circuitry to allow the filtering to be adjusted on the fly. Something to allow the capacitance in the filter to be changed...even a 3 -position switch would be great. I'm going to be thinking about that this winter....which, according to the weatherman, is going to start this afternoon. Supposed to be 16 in the morning, with light snow on the ground.

Jim

Keep us posted on your idea.

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  • 2 weeks later...

My Metal Detecting Buddy thought that this model may differ internally from the standard SL in that it may have some of the mods or updates that have become so popular with it's fans.

Any thoughts?

Thanks!

Walt

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On ‎10‎/‎9‎/‎2019 at 1:28 PM, Jim in Idaho said:

Thinking about the sweep speed. it would be nice, on the SL, to have a small bit of circuitry to allow the filtering to be adjusted on the fly. Something to allow the capacitance in the filter to be changed...even a 3 -position switch would be great. I'm going to be thinking about that this winter....which, according to the weatherman, is going to start this afternoon. Supposed to be 16 in the morning, with light snow on the ground.

Jim

Jim, if you ever get your hands on the new TDI coil that has been advertised, let us know.

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