TDI Pulsescan modifications AND BIG coils

Prospecting Australia

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no prob detecting my pallasite & siderite slices :)

only wish I had found the original myself...

1642145064_meteorites_1.jpg
 
Please forgive my absence, I've been struggling with Omicron COVID and have been pretty tired. I am 3x vaccinated so the symptoms, beyond fatigue, have been mild.

EVERYONE is this country has Omicron, had Omicron, or is about to get Omicron. My wife is recovering as well.

This country has not responded well to the pandemic--very few masks are being worn.

Should be better tomorrow!

Rob
 
Well... I'm back. More or less. (Headache and tired early in the evening.) Also, my youngest daughter and her fiance are now recovering from COVID. Daughter was 3x vaccinated and her symptoms have been mild, mostly fatigue. Fiance was only 2x vaccinated and he has fractured ribs from coughing so hard and long--he's been rather ill.

Get 3x vaccinated, the difference in COVID illness is remarkable.

Question: The size of the coil is a BIG factor in depth, no? So, if that is true, doesn't this make sense: Detech 32" Concentric Search Coil.

1643161257_detech32concentriccoil_1000.jpg


A super large coil also allows you to cover a lot more country, as in open farm fields, no?

Also, is the machine more or less stable will super big coils? Any other advantages or disadvantages?

I hope all is good and your your summer's are going well.

Rob
 
Another question, a little off topic, but I thought I would ask.

I've notice a HUGE DIFFERENCE with both the TDI and VLF (ETrac) detector when detecting old, large iron. With the ETrac big iron objects scream at extreme depth--it's incredible. And also, there is a detectable halo around long buried iron objects, you can be 4-feet off-target and still be getting a signal.

Question: How much different is gold and silver coins in detectability than iron. (I've only discovered a few silver coins and they were only an inch deep.)

If three (3) samples of metal: (1) 19th century iron, (2) gold coins, (3) silver coins, each sample the size of your fist, :fistpump: were buried at 30 cm increments (30, 60, 90, 120 cm) how would the detection differ (PI and VLF) at those depths? Iron = 1st, Silver = 2nd, Place Gold = 3rd?

How deep can you detect each of these, knowing iron is super easy.

Rob
 
Huge coils are a PITA unless ground is flat and devoid of sticks bushes etc

I have never had the pleasure of a fistfull of gold coins to bury, or even silver for that matter.:) For any targets of exactly the same geometry the most conductive will be detected deeper by any machine so Ag deepest then Au then Fe.

Similarly for all else being equal VLF vs PI distance comes down to ground mineralisation - mild= VLF deeper, high mineralise = PI deeper.

Since the real answer is "it depends "- depends on detector, coil, ground, target, settings ....., the best way is for you to go play with your own 2 detectors in your own area with your own targets and answer those questions for your circumstances. Go bury those gold coins and see if you can find them again :)

Have you dug even one 120cm deep hole yet ? Thats a couple of hours of hard work even in relatively soft ground.

Try it & you might lose the enthusiasm for deep detecting given that without discrimination or truly virgin ground, the valuable item to trash ratio starts at 1:50 and can get to 1:500 .
 
Very often I detect abandoned homesteads and in and around little rural towns where a metal detector is still a true novelty. Almost every day I can and do detect a place that has never been metal detected before. Despite this, I very rarely find silver coins and I have never see a gold one in the ground. The E-Trac has the reputation of being a silver magnet. (I think it was specially {secretly} designed to be especially good with it.) It's frustrating.

I've found meteorites in Wyoming and Kansas. Gold nuggets in Colorado. Iron Indian (trade) arrowheads in New Mexico... But coins seem to evade me.

Rob
 
I had the TDI out the day before it snowed--a lot. I placed four (4) older Canadian pennies linearly in duct tape and buried them 13" deep. (Great for test gardens, old Canadian pennies are known for their high quality copper/tin (bronze) content and they sing on a VLF-machine exactly like 19th-century US pennies.

Anyway, at 13-inches, I managed to get a response from the TDI with GB turned on. (I did not document the Pulse Delay, but I'm pretty certain it was 17.5.)

Interesting thing though: the signal ALWAYS sounded as the coil moved OFF the target. No sound coming in or directly over, but always as the coil was leaving. Is this normal?

Set on 25 Pulse Delay, I didn't get anything. AND, I was experimenting with all the knobs to the point that I am not quite certain how it was set to get the detection!!

Simply said: I Have A Lot To Learn. And, the TDI is an instrument that will require use and dedication to master.

Rob
 
THANK YOU!

The manual that came with my NEW TDI Pulse Scan (in the box) was a pre-print Draft copy, and it is hard to read and not very good.

Downloaded it and THANK YOU, once again.

Rob
 
Hmm , cant say I recall ever having that "1/2 response" for a target. Try swinging at 90 deg ie E-W if you were swinging N-S before to see if it is some weird target orientation thing or the detector itself.

Do you have that 1/2 response with a reasonable signal or is it a weak, limit of detection sound.

I have seen something a bit similar with variable mineralised ground where you get a response swinging in one direction and not the other but the signal has been from ground not target.

If your VLF detected the pennies at 13" then should be reasonably mild ground. What was your GB setting?
 
AVXVA said:
I had the TDI out the day before it snowed--a lot. I placed four (4) older Canadian pennies linearly in duct tape and buried them 13" deep. (Great for test gardens, old Canadian pennies are known for their high quality copper/tin (bronze) content and they sing on a VLF-machine exactly like 19th-century US pennies.

Anyway, at 13-inches, I managed to get a response from the TDI with GB turned on. (I did not document the Pulse Delay, but I'm pretty certain it was 17.5.)

Interesting thing though: the signal ALWAYS sounded as the coil moved OFF the target. No sound coming in or directly over, but always as the coil was leaving. Is this normal?

Set on 25 Pulse Delay, I didn't get anything. AND, I was experimenting with all the knobs to the point that I am not quite certain how it was set to get the detection!!

Simply said: I Have A Lot To Learn. And, the TDI is an instrument that will require use and dedication to master.

Rob
Click to expand...

I have noticed that delayed tone with some aftermarket coils where the target signal was slightly off centre but nothing drastic.
Ground balancing, auto retune vlf detectors can do that depending on ground minerals.

You are not using wireless headphones by any chance. The cheapies have a signal delay that can be irritating.
Is that delay with both fast and slow sweep speeds?....Maybe slow your sweep speed down a bit?

Unusual for a PI to have a signal delay. .
I have been trying to reproduce your fault with various hot rocks, gb on and gb off and delay settings on my TDI but have not been able to do so.
 
To answer XLOOXs question, the E-Trac VLF detector has automatic GB and it sees the 4-penny target at 13-inches on every Automatic setting. On Manual it sees it at a 10 out of 30 Gain (1/3) power. The E-Trac is unbeatable among VLF detectors--with one giant exception. ~> It is an aluminum finding mad dog. The E-Trac was specially designed to hit silver and apparently aluminum was accidentally enhanced too. The aluminum signal on an E-Trac displays on and between a US $10 gold coin and a US $20 gold coin. There is no known aluminum discrimination setting.

However, I was AMAZED to discover today that the TDI discriminates out aluminum shockingly well. This ability alone makes it an amazing machine.

I was experimenting with the TDI on coins today, and I must say, I am very impressed. The TDI does not mess around. With Pulse Delay = 17.5, Gain = 6 and GB = 6 with the toggle set to Conductive, the TDI absolutely hammers coins--except US nickels which are low conductors. AND, the machine discriminates aluminum like a charm.

There is no maybe it is there and/or maybe it is not with the TDI. It is a very forthright machine.

Rob
 
The ability to knock out small iron, hair pins and fish hooks.. while still hitting gold and combined with good depth makes it a very versatile machine. I'm loving the Tdi Pro with the Nuggetteer 18 x 6 mono, good balance and great ground coverage. It is a beach monster, the coil is highly resistant to EMI and punches deep. The Tdi is not the latest or the greatest, but on the beach it does very well.
1644409608_1579774718_img_1712_edited.jpg


Set it up to disk iron and you miss on Australian $1 and $2 coins, but still hit gold rings etc. Expect less depth, roughly 10 to 20 percent. A killer combo in the shallows and wet sand but too much work in the dry sand areas. Large coils on the Tdi can work well, a versatile and honest machine. All the best.
 
Does it make sense to use the TDI with a 32-inch coil for scouting gold? Say you`re way out in the desert with a dozen different dry washes that all look the same (in a 50-square mile chunk of country) and you don`t what has gold and what does not.

The 32-inch coil covers a lot of ground. Can you test / survey a bunch of dry sinks and holes with the 32 in a speedy way until the TDI starts to talk? I`m thinking being on a 4-wheeler and covering a lot of country fast--ten minutes in each place--test and go.

Will it work?

Rob
 
Is there an online tutorial or book that provides a step-by-step (and I do mean `step-by-step`) explanation and parts list on how to make a DIY 1-meter (36-inch to 40-inch) concentric or dual-field coil for the TDI PI detector?

I want to make a BIG coil that has wheels like a GPR unit--but with taller wheels--and with a coil height adjustment. I`m going to push it around like a shopping cart.

Rob
 
How is everyone's winter going? Summer here has been remarkably bearable--no complaints.

A couple of questions!

With the GEB circuit turned OFF (Ground Balancing Knob = Inactive) the PulseScan TDI ground balances using it's internal circuitry alone. Is it possible to use the Threshold to quasi-ground balance? That is to turn the Threshold way down so the machine is mostly silent. The TDI comes to life over a shallow target doing this, but am I kidding myself?

I am seriously considering spending a stupid amount of money on a Detech 32" Concentric coil. I need 5 or 6 feet or more of depth to located football-sized or larger chunks of meteorite in western Kansas. And the ground is really dry. My VLF isn't cutting it. Am I wasting my money?

Does anyone have experience with these super-sized coils on a TDI?

Thanks!

Rob
 

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AVXVA said:
With the GEB circuit turned OFF (Ground Balancing Knob = Inactive) the PulseScan TDI ground balances using it's internal circuitry alone. Is it possible to use the Threshold to quasi-ground balance? That is to turn the Threshold way down so the machine is mostly silent. The TDI comes to life over a shallow target doing this, but am I kidding myself?
Click to expand...
The problem with a silent threshhold is that deep targets (at the detector depth limits of the coil/machine), can register as a negative signal, where the threshhold volume dips rather than rises. If you are running your machine with a silent threshhold at the time, you will walk over these potentially great targets without having any inkling of their existence, even though your gear detected them.
 

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