TR disc

I have an old Stingray that I sent to Tesoro and had the leaking coil replaced. It has a TR discrimination mode. On one of the forums, someone tells of when. during a sidewalk removal, a person with an old TR detector found more than the new detectors because "it didn't see the iron'. The Tesoro manual does not explain very well how to make it work. I need help in figuring out how to set the Stingray up to take advantage. Does the ground balance have an influence? Is the discrimination markings the same as for regular disc? Any tips? HH and thank you for your time.

The GB circuit isn't used in TR Disc mode...which is why mineralized ground eats TR Disc detectors for lunch.
(The all-metal and Motion Disc use the GB circuit.)

The three modes the Stingray has are:
VLF/TR/VLF Discriminator.
It can be used as an ALL METAL detector, as a TR discriminator, or as a Motion based discriminator.

Note the implication of the term "Motion based"...and it's inverse.
The TR Disc mode does not require motion to disc.
That is one of it's 'super powers', LOL.

We're so used to keeping the coil in motion with the newer designs, we've forgotten the advantages of slowly sneaking the coil around in trash.
For those who never used an old TR, you might think of it as having an infinitely fast recovery speed.

To use it, (or pretty much any T/R machine):
1. Set the threshold level for a just barely audible tone.
2. Start with a fairly high sensitivity, and decrease as necessary later. (Important, as these things aren't particulary depth demons)
3. Set the disc to the lowest level you can stand...like foil...or live with the depth loss of adding extra disc to eliminate things like pull tabs. (Unlike today's machines, adding more disc to a TR drastically cuts depth.)
4. Tune the unit with the coil just above the ground.

Slowly lift and raise the coil. If the ground mineralization is pronounced, your threshold level will make abrupt/harsh changes.
If it does, you may have to reduce sensitivity to make it stable enough to even use.
(If the threshold changes are mild/minimal, it's fine...there will always be some threshold shift as you get into 'ground-effect'.)

Swing slowly, and listen for clean, un-clipped tones...keeping the coil height as even above the ground as possible.
(You can swing much more slowly than possible with modern machines...experiment.)

Depending on the unit, it may not have SAT, so you'll have to baby-sit the threshold level, and re-tune frequently.
(It's not all that bad, and you adapt pretty quickly.)

Have fun.

Caveats:
Mineralization is Kryptonite to a TR Disc detector. If the ground is clean (mineral-wise) ...like most of the Midwest...they work pretty well.
But if not, they perform as badly as SuperMan with a Kryptonite necklace.
Also note the performance hit of adding disc. (You can actually see that with air testing.)

Enjoy,
mike



Edited 2 time(s). Last edit at 05/06/2019 09:22PM by Mike in CO.

One you get it setup, you should experiment with some nails, foil trash, and coins in your yard...just to see how close you can get them together.
I think you'll be pleasantly surprised.

Mike gives a pretty good wrap-up ! However, the only thing I would add is:

Don't confuse "all-metal TR" with "disc. TR". I don't know where the Stingray's TR fits in with this discussion, but :

I think most all of the TR disc's ever put on detectors, did NOT have the "nail-see-through" ability. It was only all-metal TR that could do that trick. The all-metal TR's (like the 77b and 66TR) would have zero ability to discriminate anything (foil, tabs, etc...) yet would not beep on small iron (individual nails). Only larger iron like domino sized cast-iron pieces, or very big nails (RR spikes, etc...) would bleed through (albeit with tell-tale audio). But for solo rusty nails, it would not only null over them, but sort of see-through them (eliminating masking) as well. Up to a degree anyhow. By the time you added the 3rd or 4th nail over a test coin, you'd start to loose the coin. Depending on nail sizes, placement of coin, etc.....

But with TR disc. on machines like the original 5000D, or Groundhog, and so forth : No, the TR on those machines was not the same type of TR.

To further clarify the distinction, I believe that it had something to do with the internal fixed points of calibration on the internals of the control pots. So what I mean is: The TR on each was actually the same principle. But that TR "disc" bottom-most level of disc. was typically set high enough , that you no longer saw through nails . But apparently some other TR disc. machines had their "lowest setting" that mimicked the all-metal TR ability of earlier all-metal TR machines.

I forget which machines had which. This is a question for Monte !

Tom,
Probably the biggest advantage of those early Compass models (for it's efficiency in iron) was it's operating frequency...over 100k.
Compare to the later TR Disc machines running at around 17k, (and lower) make the Compass work great in iron.

However those old TR Disc machines still had/have the advantage of not being nearly as sensitive to the motion detectors effect/habit of 'masking' adjacent targets.
Most of my TR machines can easily see a dime and a rusty nail (or two..or three) all held together...it's a beautiful thing.



Edited 1 time(s). Last edit at 05/06/2019 10:11PM by Mike in CO.

Mike in CO Wrote:
-------------------------------------------------------
> Tom,
> Probably the biggest advantage of those early Comp
> ass models (for it's efficiency in iron) was it's
> operating frequency...over 100k.
> Compare to the later TR Disc machines running at a
> round 17k, (and lower) make the Compass work great
> in iron.
>
> However those old TR Disc machines still had/have
> the advantage of not being nearly as sensitive to
> the motion detectors effect/habit of 'masking' adj
> acent targets.
> Most of my TR machines can easily see a dime and a
> rusty nail (or two..or three) all held together...
> it's a beautiful thing.


Thanx for clarifying the different types of TR. Thus not all TR's are the types that were touted as seeing-through-nails.

Yes, In the early days of motion disc (6000d, 6db, etc...) they were prone to have "tails" in the swings/responses. Thus they were more prone to masking. So even though they went much deeper, and covered ground much faster than TR disc, yet TR still had the ability to separate targets better. As time went on (through the 1980s and '90s) that swing speed got slowed down, to the point where it's a "crawl" these days. So that masking is less pronounced nowadays, for today's motion machines.

So whatever benefit the early TR discriminators had over the early motion discriminators, was not a function of "see-through" (like the all-metal TR's had), but rather, a function of separation. Because with the TR discriminator you could "stop right on top of the target", to "see" the slightest little peak of the target. Versus the motion machine , where you had to be constantly swinging. On the TR discriminators though, if the coin were *truly* dead-center under a nail, it would mask. It would not do the averaging see-through trick like the all-metal TR's could.

Thanks Mike! That was what I was looking for. I have an old Compass Judge II and the tips will help there too. I believe it has both all metal TR and discrimination TR but the Stingray is lighter and waterproof and only takes 6 batteries instead of 12! Anyway thanks guys for your help.