steve herschbach
New member
Hi,
The following is a
The following is a
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White's TDI Coin Settings and Target Responses
- Thread starter steve herschbach
- Start date
I am serious, no joke.steve herschbach
New member
Hi,
The TDI was designed first and foremost to find gold. The coin hunting capability was almost an accident. I'd like to help you out, but my TDIs are already on the way to the mine and will be finding gold in a few days.
Steve Herschbach
The TDI was designed first and foremost to find gold. The coin hunting capability was almost an accident. I'd like to help you out, but my TDIs are already on the way to the mine and will be finding gold in a few days.
Steve Herschbach
Hi Jawbone,
There is no adjustment on the TDI to adjust the pulse width. The initial design of the TDI was for gold hunting and, as such, the wider pulse width appeared to be of little value when hunting the size of gold we normally find here in the US. So, my guess is the control was left off to reduce the cost of the detector. Keep in mind, I am guessing, but it makes sense.
Reg
There is no adjustment on the TDI to adjust the pulse width. The initial design of the TDI was for gold hunting and, as such, the wider pulse width appeared to be of little value when hunting the size of gold we normally find here in the US. So, my guess is the control was left off to reduce the cost of the detector. Keep in mind, I am guessing, but it makes sense.
Reg
woodchiphustler
New member
Great post Steve. I think opposite every time I use the TDI. Best regard's, George K.
William Morrow
New member
Hi guy's well I got a TDI about a week ago and have had a great time with a MXT but now think that I have bit off more than my simple mind can comprehend. I look at all the dills and the only one I understand is the off and on switch. I tried to set it up to the manual and all I found were bobby pins and bottle caps. Is there some simplicity to understand this great machine? I did purchase it with desert hunting in mind.
Hi William,
You mention you bought the TDI with desert hunting in mind, however, you then mention bottle caps and bobby pins. I don't think I ever found a bobby pin on the desert. Hmmm.
Ok, if you are making a transition from the MXT to the TDI you are in for a shock. As you have found out, there are few similarities between the two. So, the first thing to do is don't try to use any techniques you use on the MXT on the TDI. Instead, think of it as a totally new machine that has to be learned from scratch.
Now, with that said, there are a few most general similarities between the TDI and a VLF and those are, the ground balance normally adjusts the signal so one gets the least ground signal when the coil is bobbed on either machine. Also, the sensitivity on both types of detectors generally sets the gain or depth capabilities. The threshold on both does the same and sets the audio level we hear with no target present. the ON/OFF switch is a given in the fact it does just what it says it does.
So, now we are left with the Delay and a switch called the conductivity to learn. To learn just how the conductivity control works, requires one to better understand how a PI works and what happens when we adjust the ground balance. In other words, there is a direct relationship and interaction between the two controls. Both of these controls will interact with the Delay, so to fully understand this PI you will have to have a good idea of just what is happening when you adjust any or all of these controls.
Now, to fully describe all that can happen or will happen will take quite a report, so it would be best to find lengthy write-ups on these controls on this forum and on the TDI tech forum. In the interim I will try to summarize the controls now.
PI's operate on the principle of generating a very strong pulse in the coil and shutting that pulse off as quickly as possible. When that happens, the coil signal will jump to a very high voltage and then begin to decay (drop down quickly) until it gets to 0 volts. Once the decay is at 0 volts, a small sample is taken of that signal. If an object comes into the field of the coil this decay will be altered and when the sample is taken, the voltage will no longer be 0 V but will be some other voltage depending upon the type and size of the target. So, the voltage will be different.
Now, this sample voltage is held in what is called an integrator where additional samples are added and averaged. So, if a target comes into the picture this sample hold voltage will increase to a level determined by the target. This increase in voltage is amplified and becomes the signal we hear.
Now, to obtain the ground balance a later sample is taken and again is held in a different integrator where that signal will be amplified. This later signal is then amplified sufficiently that the ground signal is strong enough that when this later signal is subtracted from the main sample signal, the ground signal will cancel, thus one will hear little or no ground response. This will usually happen at about 9 on the GB scale when the delay is at 10 usec. Change the delay and the ratio changes so a different setting will be required.
Now, one must keep in mind that when the later sample is amplified, that sample will contain both the ground signal and the signal from a target also. So, the target signal is also amplified and ultimately subtracted also. Knowing this is very important. Also it is important to know that most targets decay at a different rate than the ground signal with some decaying sooner and some taking longer.
Now, what is also important to know is the GB control adjusts the gain of the later sample signal voltage. So, turn up the delay and the subtract signal is greater, thus allowing the operator to find just the right voltage to make the ground signal cancel.
Now, remember that other signals from targets are also present and those signals that decay sooner will generate a positive signal and those taking longer will generate a negative tone if the GB control is set high enough for the subtract process to cause the voltage switch.
Ok, here is where it can get sort of complicated to understand. Lets say the ground signal cancels at a GB level of 9. At that setting, some other targets already are strong enough to cause a negative response. Such targets are nails, silver and copper coins, and many other higher conductive objects. Turn the GB back to something like 5 and many nails no longer create a negative signal, but silver and copper coins still do.
Now lets look at the conductive switch. The settings are high conductor, low conductor or both. If we set the control for high conductor, only those targets that respond as a high conductor will cause a signal. If we set the control for low conductor, then only those targets that act like a low conductor will cause a signal. If set for both, then all targets will cause a signal.
Now, getting back to the nail and coin setting where the GB is at 5, most nails or at least many will now cause a high tone which is what a low conductor target does. The coins are still high conductors so they will still cause a low tone. Select the HI conductor position and you will only hear the coins and not the nails. Select the low conductor setting and you will only hear the nails and not the coins.
Adjust the GB and you can alter just what target will be a high conductor or a low conductor within a certain range of targets. Some objects will not change regardless of the GB setting. Tinfoil like that found on gum is one of them. It will always be a high tone or a low conductor.
So, go to a park, select high conductor mode, turn the GB back to 4 or 5, leave the delay setting at 10 usec, and you can hunt for older silver and copper coins and ignore most nails, foil, bottle caps, bobby pins, etc. You could turn the delay up to 17 as mentioned in the manual but the GB settings will change as to where they reject nails, so keep that in mind.
Dealing with low conductive trash targets is a different topic that is more complicated and would take a whole lot more writing. That is why I mentioned the other forum where the topic has been thoroughly discussed.
One final note, most people who move from a VLF to the TDI have a very difficult time adjusting. That is normal and will not happen over night. It does take time and patience. Unfortunately, many people do not want to take that time. For those who do and fully learn the detector, they will find it will open up new areas and find targets at greater depths that thought of before. At least it does in areas where the ground is difficult to hunt.
Reg
You mention you bought the TDI with desert hunting in mind, however, you then mention bottle caps and bobby pins. I don't think I ever found a bobby pin on the desert. Hmmm.
Ok, if you are making a transition from the MXT to the TDI you are in for a shock. As you have found out, there are few similarities between the two. So, the first thing to do is don't try to use any techniques you use on the MXT on the TDI. Instead, think of it as a totally new machine that has to be learned from scratch.
Now, with that said, there are a few most general similarities between the TDI and a VLF and those are, the ground balance normally adjusts the signal so one gets the least ground signal when the coil is bobbed on either machine. Also, the sensitivity on both types of detectors generally sets the gain or depth capabilities. The threshold on both does the same and sets the audio level we hear with no target present. the ON/OFF switch is a given in the fact it does just what it says it does.
So, now we are left with the Delay and a switch called the conductivity to learn. To learn just how the conductivity control works, requires one to better understand how a PI works and what happens when we adjust the ground balance. In other words, there is a direct relationship and interaction between the two controls. Both of these controls will interact with the Delay, so to fully understand this PI you will have to have a good idea of just what is happening when you adjust any or all of these controls.
Now, to fully describe all that can happen or will happen will take quite a report, so it would be best to find lengthy write-ups on these controls on this forum and on the TDI tech forum. In the interim I will try to summarize the controls now.
PI's operate on the principle of generating a very strong pulse in the coil and shutting that pulse off as quickly as possible. When that happens, the coil signal will jump to a very high voltage and then begin to decay (drop down quickly) until it gets to 0 volts. Once the decay is at 0 volts, a small sample is taken of that signal. If an object comes into the field of the coil this decay will be altered and when the sample is taken, the voltage will no longer be 0 V but will be some other voltage depending upon the type and size of the target. So, the voltage will be different.
Now, this sample voltage is held in what is called an integrator where additional samples are added and averaged. So, if a target comes into the picture this sample hold voltage will increase to a level determined by the target. This increase in voltage is amplified and becomes the signal we hear.
Now, to obtain the ground balance a later sample is taken and again is held in a different integrator where that signal will be amplified. This later signal is then amplified sufficiently that the ground signal is strong enough that when this later signal is subtracted from the main sample signal, the ground signal will cancel, thus one will hear little or no ground response. This will usually happen at about 9 on the GB scale when the delay is at 10 usec. Change the delay and the ratio changes so a different setting will be required.
Now, one must keep in mind that when the later sample is amplified, that sample will contain both the ground signal and the signal from a target also. So, the target signal is also amplified and ultimately subtracted also. Knowing this is very important. Also it is important to know that most targets decay at a different rate than the ground signal with some decaying sooner and some taking longer.
Now, what is also important to know is the GB control adjusts the gain of the later sample signal voltage. So, turn up the delay and the subtract signal is greater, thus allowing the operator to find just the right voltage to make the ground signal cancel.
Now, remember that other signals from targets are also present and those signals that decay sooner will generate a positive signal and those taking longer will generate a negative tone if the GB control is set high enough for the subtract process to cause the voltage switch.
Ok, here is where it can get sort of complicated to understand. Lets say the ground signal cancels at a GB level of 9. At that setting, some other targets already are strong enough to cause a negative response. Such targets are nails, silver and copper coins, and many other higher conductive objects. Turn the GB back to something like 5 and many nails no longer create a negative signal, but silver and copper coins still do.
Now lets look at the conductive switch. The settings are high conductor, low conductor or both. If we set the control for high conductor, only those targets that respond as a high conductor will cause a signal. If we set the control for low conductor, then only those targets that act like a low conductor will cause a signal. If set for both, then all targets will cause a signal.
Now, getting back to the nail and coin setting where the GB is at 5, most nails or at least many will now cause a high tone which is what a low conductor target does. The coins are still high conductors so they will still cause a low tone. Select the HI conductor position and you will only hear the coins and not the nails. Select the low conductor setting and you will only hear the nails and not the coins.
Adjust the GB and you can alter just what target will be a high conductor or a low conductor within a certain range of targets. Some objects will not change regardless of the GB setting. Tinfoil like that found on gum is one of them. It will always be a high tone or a low conductor.
So, go to a park, select high conductor mode, turn the GB back to 4 or 5, leave the delay setting at 10 usec, and you can hunt for older silver and copper coins and ignore most nails, foil, bottle caps, bobby pins, etc. You could turn the delay up to 17 as mentioned in the manual but the GB settings will change as to where they reject nails, so keep that in mind.
Dealing with low conductive trash targets is a different topic that is more complicated and would take a whole lot more writing. That is why I mentioned the other forum where the topic has been thoroughly discussed.
One final note, most people who move from a VLF to the TDI have a very difficult time adjusting. That is normal and will not happen over night. It does take time and patience. Unfortunately, many people do not want to take that time. For those who do and fully learn the detector, they will find it will open up new areas and find targets at greater depths that thought of before. At least it does in areas where the ground is difficult to hunt.
Reg
Hi Therover,
If you go to the Whites TDI tech forum (google it if my link is removed), there is more info on how the TDI works including this subject of the conductivity, ground balance and the conductivity control. Here is the link;
http://tdi.invisionplus.net/?mforum=tdi&act=SF&s=&f=3
The TDI forum has a lot of info on the TDI and how it works. Much of this info is applicable to Eric's GS 5 series also.
Reg
If you go to the Whites TDI tech forum (google it if my link is removed), there is more info on how the TDI works including this subject of the conductivity, ground balance and the conductivity control. Here is the link;
http://tdi.invisionplus.net/?mforum=tdi&act=SF&s=&f=3
The TDI forum has a lot of info on the TDI and how it works. Much of this info is applicable to Eric's GS 5 series also.
Reg
Best site I know of to learn about the TDI. Bad thing is, every time I do there and read, I want one more and more ! Seems this machine is one of the simplest yet fully adjustable machines out there.
One of the main applications I am thinking about is beach hunting, where there are sections of beach where it's pretty clean and then you run up on patches of sand where there are lots of nails or iron targets, yet there may be other non-ferrous targets among them.
When using my standard PI machines, I have to either dig all, or move on. Thinking that the TDI may be able to hunt these areas ( ok, maybe not with the depth when in pure PI mode) but at least I may be able to hunt the area and not be driven crazy by diggin all the nails.
I also really like the video posted of the 7.5 inch coil hitting the targets on the side walk, and discrimination out the nails and still hitting the silver and clad. Cool stuff.
John
One of the main applications I am thinking about is beach hunting, where there are sections of beach where it's pretty clean and then you run up on patches of sand where there are lots of nails or iron targets, yet there may be other non-ferrous targets among them.
When using my standard PI machines, I have to either dig all, or move on. Thinking that the TDI may be able to hunt these areas ( ok, maybe not with the depth when in pure PI mode) but at least I may be able to hunt the area and not be driven crazy by diggin all the nails.
I also really like the video posted of the 7.5 inch coil hitting the targets on the side walk, and discrimination out the nails and still hitting the silver and clad. Cool stuff.
John