Jim in Idaho

2 hours ago, Mark Gillespie said:

These test were with a nickel approaching the coil, not simulating an actual sweep, right to left.

I was listening for a slight increase in threshold.

Still, I thought it did better than this.

An 18 volt battery pack my help.

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

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

The "deeper with GB on" is true with the SL, but apparently not the others. Auminesweeper is right, and my tests also bore it out. Regardless of the GB setting, as long as it's "on" the air tests show a definite improvement. Reg S. and I discussed this at length, and didn't come to any conclusions as to why, though Reg mentioned the GB circuit on the SL is different than the other TDI's.

Jim

On 4/19/2019 at 6:58 PM, GB_Amateur said:

Are you referring to the the White's NiMH pack?  I have an R&B Li-ion pack which I just measured at 12.35 V.  (I think when fully charged it is closer to 12.5 V.)

One thing to keep in mind regarding all batteries (rechargeable and single-use) is that the stated voltage is a nominal value, and the initial (fully charged) value usually lasts only a short time.  There is a plateau (approximately constant) value which occurs for most of the battery's life which is typically a fair amount below the initial full charge.  Most of the time (marketing trickery?) the plateau voltage is below the advertised/stated voltage.

Most modern electronics (including most metal detectors) use voltage regulation circuitry which converts the supplied voltage to a fixed value, regardless of the actual supply voltage, within limits.  The White's TDI/SL is apparently a rare exception to this practice.

 

 

 

The PI detectors use a voltage regulator on the Receiver, but the transmit circuitry is current driven, so a higher battery voltage means a stronger pulse into the ground. My personal theory on why this mostly pertains to the larger coils is that the smaller coils are "maxed out", or saturated, at the regular 12v nominal, so don't benefit much from the higher voltage.

Jim

Mark, he has a hard time with typing anymore, so seldom posts, unless he has something of real value to add to a discussion.

Jim

On 4/28/2019 at 5:17 AM, Mark Gillespie said:

It must have been a very bad crash or they had a cyber attack of some sort.

http://forums.whiteselectronics.com/

Yeah, I tried to login...no go. Also tried to register, but it asked me to choose a subscription to buy, with no

choices. I sent a note to Vbulletin about it. Maybe they can straighten it out.

Jim

10 hours ago, Lunk said:

WTG Oneguy! Hopefully the tick population was decimated by the cold weather this winter...I could do without the little blighters.

From what I see up here in Idaho & Wyoming, cold weather has no impact on ticks. Many of them even at elevations above 7,000', where it gets way below zero. One of 'em in Wyoming got me a few years ago, and I ended up with Rocky Mountain Spotted Fever. Now I treat all my outdoor clothing with Permethrin, and my skin with Picaridin. Tick diseases are really nasty.

Jim

1 hour ago, Steve Herschbach said:

Huge long thread with tons of photos that anyone should be able to follow. Plus I added a link a couple posts back.

Garrett ATX Strip Down & Rebuild

Thanks, Steve.

Jim

Hey Steve. is there a file somewhere showing how you did the Mod? I remember reading it, but would like to have the whole thing. I might get around to doing that myself.:-)

Jim

My pleasure, Mark. It's nice to be able to make a contribution to the forum. I've looked at, and enjoyed your videos, too, and appreciate your efforts to educate us on the TDI SL.

Jim

More on this subject.....I'm just going to attach the files, as I find them

Jim

TDI SL Tests.doc

Mark, I think the entire results were posted on the White's forum on Findmall, and I may have posted them on the White's factory forum, too. I'll do some looking around. I did some other testing, too. I may have all that in my PC, too. haven't looked at it  for a while.

 I did some looking and found this in my files, on the 7.5DF:

Battery Voltage tests Whites TDI SL 7.5"DF coil

Freq: centered: Pulse Delay: 10: Gain: Max

!6.2V

                      Nickel                             1 grain Gold Bar

GB OFF:        10.75"                                      2.75"

GB ON    Switch in "all"

  Min.              12.75"                                      2.75"

  Max.              13.25"                                     3.00"

GB On      Switch set in "low"

                        N/C                                           N/C

12.3v             Nickel                              1 grain Gold Bar

GB OFF           11.0"                                       2.75"

GB ON

  Min.                12.75"                                     2.75"

  Max.                13.0"                                       2.75"

Jim

This has nothing to do with Findmall. It's White's Factory forum...not the Whites forum/forums on Findmall.

Jim

I did a whole series of tests, on the TDI SL, and 16.8v battery. at the request of Reg S. He had particular rules about how the tests would be performed. In a nutshell, the results were a definite improvement in both depth, and sensitivity to small items. But the improvement only came with the larger coil. The smaller coils tested included the MJ 5 x 9,  and the 7,5"DF. Neither showed much improvement over the 12v battery. Reg and I discussed this, and did not come to a conclusion on the reasons. My thought was that the smaller coils are saturated at 12v, and the extra voltage doesn't allow any more current into the generated magnetic field. On the 12"DF, however the improvement was about 20% as I recall. With the 12"DF, my SL can see a 1 grain nugget at 3" in an air test. It can also see a nickel at 16.5". Best depth was with the target moving vertically toward the coil. That was one of Reg's rules for the testing. I had posted all the test results, but don't remember where. This was about 3 years ago.

Jim

In all the testing I've done, I got the deepest results, regardless of coil used, or battery voltage, with GB on. Just saying.

Jim.

I heard from Steve Howard Monday morning. He said they hoped to have it up this week.

Jim

My testing indicates the 12"DF is very good. Only exceeded by the Nugget Finder 8 x 6 Sadie, and the Sadie, while being more sensitive to really small gold, doesn't match the 12"DF for depth on the bigger items. That said, I haven't tried any of the larger coils by other manufacturers. I liked using the MJ 5 x 9, but it didn't equal the Sadie on the small stuff. The only thing I didn't like about the 12'"DF is it's cumbersome for prospecting in rough terrain.

Jim

Here ya go...The other one is the T38 Talon. I spent the summer of '71 at the training base for the T38 in Arizona. I was a radar tech.

Thanks for the update!

Jim

Haven't been able to get on there for a couple of days. I'm wondering if they stopped having the forums?

Jim

Yeah, John, Vegas was cancelled too. Either GPAA is losing money, or the owners are keeping more of what they do make.

Jim

4 hours ago, LipCa said:

Maybe you can still get in the ICMJ show in CA?

I don't want to go that far this spring. I do think ICMJ is a good place to advertise, and will be pursuing that shortly.

I could also do the Elko show in June, but it's a little spendy. We'll see how things go.

Jim

5 hours ago, Steve Herschbach said:

Interest is on the decline unfortunately and the number of shows is therefore dwindling.

I agree Steve. That's also why Tesoro is having problems. We need a big jump in the gold price again. Every time that happens, things get going.

Jim

Dang, I was planning on getting a booth to demo the Sweep Jig. Can't find any mention of the Boise show on the 'net.

Jim

The changes to the TDI SL were about increasing the sweep speed, without loss of sensitivity to small nuggets. That was accomplished by changing the aforementioned capacitor values. Here's what Reg posted on this mod.

"The caps being removed are C20 &21, .47uf and will be replaced with .22uf. Use 50v Panasonic, or Rubicon Stacked Metal Film Polyester type." Credit to Reg Sniff

The only other change was increasing the battery voltage to 16.8 volts. There is a small risk of trouble by doing that. The capacitors in the power supply are only rated for 16v. But I don't know anybody that has used the higher voltage that has had problems. I've been using the 16.8v pack for 2 years. It does make a substantial difference in depth and sensitivity.

Jim