The Sand Shark's Pulse Delay

Status
Not open for further replies.

Terry Soloman

Elite Member
Forum Supporter
Joined
May 23, 2011
Messages
6,044
Location
White Plains, NY and Congress, AZ
There is a lot of controversy over "Pulse Delay," and its importance to depth and small target sensitivity. Unfortunately, most people don't understand that a setting of 10us pulse delay, is very noisey and unsteady on wet ocean sand. So even though you may be getting more sensitivity to smaller targets, you might not hear them.

Now, move your coil from the wet sand and into the water and you will have to increase your pulse delay to at least 15us to smooth out the threshold. By the time you have reached a depth of five-feet in saltwater, you'll need a pulse delay of about 20us.

Those who fault the Tesoro Sand Shark for running a 19.5us pulse delay, instead of a 15us pulse delay, claiming it is less sensitive or lacks depth compared to other machines costing twice its price are welcome to their opinion, but if you are a water hunter and have used the different machines like I have, you know better.

The pulse delay must be coupled with power to the coil, and circuitry that filters and reads the return signal. The performance of a machine is NOT based soley on pulse delay. That is my opinion, and why I think I would rather have a set pulse delay of 20us, than 15us.

Placing my flame retarding long johns on now.. :cool:
 
Target response also is dependant on pulse width and sampling timing.

EVERYTHING is a trade off. When you enhance one aspect, you degrade another.
 
Do you ever take a day off? Here it is Sunday and you're still stirring the pot. And you wonder why the numbers keep growing each week with the people that disagree with your posts. We won't even go into the silent majority :lol:
 
Do you ever take a day off? Here it is Sunday and you're still stirring the pot. And you wonder why the numbers keep growing each week with the people that disagree with your posts. We won't even go into the silent majority :lol:

I couldn't have said it better myself... :D
 
Terry, I love you man! You really love that SS..

Terry
but if you are a water hunter and have used the different machines like I have, you know better.

I have one question, and maybe I'm just a slow learner. Been using the Excalibur's for about 6 to 7 years now, Finally...... at this point I feel I have come to know Mine well enough I can hunt with the best.... But give me another, like the CZ20, DF, GoldScan, infinium, or even A bone Stock Excalibur II (which all I have and have used but alot less time)..I feel like a rookie and would have a hard time saying that I could pick up one and give it a honest Evaluation. Could you tell us which water machines you have used, and the amount of time it took you tweek them to there fullest (like the SS) and maybe we can see your point..

Terry
Placing my flame retarding long johns on now
Thats funny!
 
I have one question, and maybe I'm just a slow learner. Been using the Excalibur's for about 6 to 7 years now, Finally...... at this point I feel I have come to know Mine well enough I can hunt with the best.... But give me another, like the CZ20, DF, GoldScan, infinium, or even A bone Stock Excalibur II (which all I have and have used but alot less time)..I feel like a rookie and would have a hard time saying that I could pick up one and give it a honest Evaluation. Could you tell us which water machines you have used, and the amount of time it took you tweek them to there fullest (like the SS) and maybe we can see your point..

OBN, your intelligences I have to admire.
 
There is a lot of controversy over "Pulse Delay," and its importance to depth and small target sensitivity. Unfortunately, most people don't understand that a setting of 10us pulse delay, is very noisey and unsteady on wet ocean sand. So even though you may be getting more sensitivity to smaller targets, you might not hear them.

Now, move your coil from the wet sand and into the water and you will have to increase your pulse delay to at least 15us to smooth out the threshold. By the time you have reached a depth of five-feet in saltwater, you'll need a pulse delay of about 20us.

Those who fault the Tesoro Sand Shark for running a 19.5us pulse delay, instead of a 15us pulse delay, claiming it is less sensitive or lacks depth compared to other machines costing twice its price are welcome to their opinion, but if you are a water hunter and have used the different machines like I have, you know better.

The pulse delay must be coupled with power to the coil, and circuitry that filters and reads the return signal. The performance of a machine is NOT based soley on pulse delay. That is my opinion, and why I think I would rather have a set pulse delay of 20us, than 15us.

Placing my flame retarding long johns on now.. :cool:

It makes sense but does pulse delay affect different metals differently? For example does it have an effect and other garbage? Edited by Admin
 
Last edited by a moderator:
Why did I look on here???? According to your own posts you found your first water gold ring on 7-11-11. Less than a year ago but your already wrighting water hunting articles for magazines and telling people that have been PI detecting for up to like 30 years they are wrong?? It is obvious that you have a pesonal agenda to make everyone think you are an expert. Go ahead and promote your name all you want but stop acting like the expert. There are members on here that you have misslead and it cost them $$$ There should be a disclaimer in your signature. You and Midas should just clear all the beaches of gold so we can all move onto another hobby. Stuff like this is why I post less on here now,tired of the bs. I can't wait to see how all this gets blown out of proportion, if I even bother to look anymore. :roll:
 
Why did I look on here???? According to your own posts you found your first water gold ring on 7-11-11. Less than a year ago but your already wrighting water hunting articles for magazines and telling people that have been PI detecting for up to like 30 years they are wrong?? It is obvious that you have a pesonal agenda to make everyone think you are an expert. Go ahead and promote your name all you want but stop acting like the expert. There are members on here that you have misslead and it cost them $$$ There should be a disclaimer in your signature. You and Midas should just clear all the beaches of gold so we can all move onto another hobby. Stuff like this is why I post less on here now,tired of the bs. I can't wait to see how all this gets blown out of proportion, if I even bother to look anymore. :roll:

Tom... Terry has been using pulse machines nugget hunting... that is where he talks about 30 years...
 
Tom... Terry has been using pulse machines nugget hunting... that is where he talks about 30 years...

Last I looked there was no Salt water in Arizona. :lol: He could be the best nugget hunter in the world for all I know but all the misinformation about water detecting makes me question everything. :?: Sorry just the way I am and I'll bet a lot feel the same but prefer to keep to themselves. I just wish I was just as smart and knew everything too. More useless (expert)babble to follow.:lol: His posts are starting to sound like the parents on the Peanuts cartoon.
 
It makes sense but does pulse delay affect different metals differently? For example does it have an effect on other garbage?

Speaking of garbage, does Tom know what you have been posting for finds on the internet?
 
Last edited by a moderator:
There is a lot of controversy over "Pulse Delay," and its importance to depth and small target sensitivity. Unfortunately, most people don't understand that a setting of 10us pulse delay, is very noisey and unsteady on wet ocean sand. So even though you may be getting more sensitivity to smaller targets, you might not hear them.

Now, move your coil from the wet sand and into the water and you will have to increase your pulse delay to at least 15us to smooth out the threshold. By the time you have reached a depth of five-feet in saltwater, you'll need a pulse delay of about 20us.

Those who fault the Tesoro Sand Shark for running a 19.5us pulse delay, instead of a 15us pulse delay, claiming it is less sensitive or lacks depth compared to other machines costing twice its price are welcome to their opinion, but if you are a water hunter and have used the different machines like I have, you know better.

The pulse delay must be coupled with power to the coil, and circuitry that filters and reads the return signal. The performance of a machine is NOT based soley on pulse delay. That is my opinion, and why I think I would rather have a set pulse delay of 20us, than 15us.

Placing my flame retarding long johns on now.. :cool:

Whoever made a claim that shorter pulse delays lead to more depth lacks an understanding of physics, geophysics and electronics.

Having said that, a detector capable of stably operating at shorter pulse delays will, everything else being equal, be more sensitive to small gold items and other so called "low conductors". Target signals are spread in time from the transmit pulse shut off. The signals will reach a peak sometime after the transmit pulse is turned off and this time is given by the geometric shape of the target, its mass and its admittance (a vector quantity combining its conductance and reactance). The signals from low conductors (including ground mineralization) are the first ones to decay after the transmit pulse is turned off. High conductors --such as silver-- peak later and will hang around a lot longer because their high conductivity do a better job of supporting Eddy currents for a longer time. Ideally, for maximum pickup, we would like the detector's sampling delay to not happen after the target's signal has totally decayed. One could envision the delay time acting as a sort of discriminator, progressively discriminating out lower conductors as we increase the delay time.

Now, we can't start sampling immediately after removing the transmit pulse. Inductors (which is what the coil is) resist an instantaneous change in current flowing through them and will respond with a very large transient voltage spike, trying to keep the current through them flowing. During this voltage spike the detector can't sample anything, it is blinded by said transient.

We may ask what determines the length of time this transient condition exists. Although there are things an engineer can do to minimize the length of time the transient takes e.g. clamping diodes, damping resistors, etc., the coil's inductance and parasitic capacitance play a large role. For depth and reception sensitivity, we want a large inductance, but how large is limited by things like coil wiring resistance, power source, design target pulse repetition rate, etc. Parasitic capacitance is something we can do without. Certainly the coil's self-resonant frequency needs to be dealt with, but in general, a larger than necessary capacitance is undesirable and may lengthen the time at which the detector is able to sample. In this regard it should be noted that --for the same inductance value-- a coil made from a spiral PCB trace will have a significantly larger parasitic capacitance than a well designed wire coil. This is plain physics and it's due to the much higher dielectric constant (µr) of the PCB substrate (usually an FR4 type copper clad material), compared to enameled wire and air as the dielectric. A detector with a PCB coil can not in general be used at lower sampling delay values as one made with a well engineered wire coil. It does however have a cost advantage as PCB spiral coils can be manufactured in a batch process and each unit has a near identical behavior, cutting down on manual tuning.

Wether a particular ground/gain combination allows the delay to be set at 10µs is immaterial. It could well allow a delay of 15µs and pick up a small gold item that may not be "seen" by a detector with a longer delay, simply because the signal has peaked and has practically decayed to nothing before the longer delay machine gets to sample the signal. Perhaps this is the reason why you may have heard some people say the shorter delay machines go deeper?

As you said, pulse delay is but one parameter of a machine's performance. Filtering, good low noise amplifiers on the receive side, coil power are also important, as are others not even mentioned.
 
So, other than insulting me and questioning my knowlrdge base and experience, I noticed that not one of you actually disputed my original post. Is that because it is factual and you can't?

Just out of curiosity, how many of you think this whole metal detecting thing is rocket science? Seriously, It takes about 50-hours for the average person to feel comfortable on most machines, although I would say the Minelab GPX probably requires more like 200-hours.

Reading a beach took me about 5-minutes to get down, just like it would anybody else that had a good teacher (in my case a Navy SEAL). Reading the mountains and learning the geology of gold prospecting is many times more difficult

I now have about 150-hours on the Dual Field; 70-hours on the Garrett Seahunter; and well over 300-hours on the Infinium. I never stated any of these machines were bad or not capable. I have repeatedly said that the Sand Shark is just as good as any of them, easier to learn, and has a better warranty for less money.

So, do ANY of you have ANYTHING intelligent to add to my original post? Anyone disagree with my assertions on pulse delay? I do get a chuckle out of the "Core-Four" here that can't stand me because I won't bend to their "superior experience and knowledge."

While the Core-Four are busy bashing my experience and knowlrdge, I would ask what articles they have written and where they are published. My very first article on Beach Detecting was publshed by Lost Treasure Magazine just this year. I guess Carla Banning decided I DID know what I was talking about.

OK. I have had a lot of fun, but unless someone really has something intelligent to add, I have more than made my point about this silly pulse delay argument. - Discuss.. :cool:
 
Now that's a great post!

Whoever made a claim that shorter pulse delays lead to more depth lacks an understanding of physics, geophysics and electronics.

Having said that, a detector capable of stably operating at shorter pulse delays will, everything else being equal, be more sensitive to small gold items and other so called "low conductors". Target signals are spread in time from the transmit pulse shut off. The signals will reach a peak sometime after the transmit pulse is turned off and this time is given by the geometric shape of the target, its mass and its admittance (a vector quantity combining its conductance and reactance). The signals from low conductors (including ground mineralization) are the first ones to decay after the transmit pulse is turned off. High conductors --such as silver-- peak later and will hang around a lot longer because their high conductivity do a better job of supporting Eddy currents. Ideally, for maximum pickup, we would like the detector's sampling delay to not happen after the target's signal has totally decayed. One could envision the delay time acting as a sort of discriminator, progressively discriminating out lower conductors as we increase the delay time.

Now, we can't start sampling immediately after removing the transmit pulse. Inductors (which is what the coil is) resist an instantaneous change in current flowing through them and will respond with a very large transient voltage spike, trying to keep the current through them flowing. During this voltage spike the detector can't sample a think, it is blinded by said transient.

We may ask what determines the length of time this transient condition exists. Although there are things an engineer can do to minimize the length of time the transient takes e.g. clamping diodes, damping resistors, etc., the coil's inductance and parasitic capacitance play a large role. For depth and reception sensitivity, we want a large inductance, but how large is limited by things like coil wiring resistance, power source, target pulse repetition rate, etc. Parasitic capacitance is something we can do without. Certainly the coil's self resonant frequency needs to be dealt with, but in general, a larger than necessary capacitance is undesirable and may lengthen the time at which the detector is able to sample. In this regard it should be noted that --for the same inductance value-- a coil made from a spiral PCB trace will have a significantly larger parasitic capacitance than a well designed wire coil. This is plain physics and it's due to the much higher dielectric constant µr of the PCB substrate (usually an FR4 type copper clad material), compared to enameled wire and air as the dielectric. A detector with a PCB coil can not in general be used at lower sampling delay values as one made with a well engineered wire coil. It does however have a cost advantage as PCB spiral coils can be manufactured in a batch process and each unit has a near identical behavior, cutting down on manual tuning.

Wether a particular ground/gain combination allows the delay to be set at 10µs is immaterial. It could well allow a delay of 15µs and pick up a small gold item that may not be "seen" by a detector with a longer delay, simply because the signal has peaked and has practically decayed to nothing before the longer delay machine gets to sample the signal. Perhaps this is the reason why you may have heard some people say the shorter delay machines go deeper?

As you said, pulse delay is but one parameter of a machine's performance. Filtering, good low noise amplifiers on the receive side, coil power are also important, as are others not even mentioned.

Great post Rudy. So, did you see a factual problem with my original post in this thread? :cool:
 
Darn..... i was about to say that Rudy. I have no idea why Terry posted this ..... was it to educate or irritate? I did notice awhile back he finally posted a hunt and got moved to the BIG SCREEN and given an badge.... so someone love him for his expertise. BUT.... when i think SS i think DewGuru.

Dew
 
Terry,

I have seen your Crazy, Trolling, posts ALL over the internet in almost ever forum that people go to for information. I see with your nutso attitude you have been ban from a few of those forums.

Personally I hope you convince EVERY hunter that is hunting Florida or is planning on hunting Florida beaches to purchase Sand Shark detectors. That is the biggest favor you could do for ALL of us seasoned hunters here in FL.

I had the enjoyment of hunting behind a Sand Shark the other day and I must say, it was most enjoyable following him with the detector I was using :lol:
 
Why did I look on here???? According to your own posts you found your first water gold ring on 7-11-11. Less than a year ago but your already wrighting water hunting articles for magazines and telling people that have been PI detecting for up to like 30 years they are wrong?? It is obvious that you have a pesonal agenda to make everyone think you are an expert. Go ahead and promote your name all you want but stop acting like the expert. There are members on here that you have misslead and it cost them $$$ There should be a disclaimer in your signature. You and Midas should just clear all the beaches of gold so we can all move onto another hobby. Stuff like this is why I post less on here now,tired of the bs. I can't wait to see how all this gets blown out of proportion, if I even bother to look anymore. :roll:

Okay comparing Terry to Midas is just down right dirty! I have taken advice from many members on the forum here. I have never felt that anyone has tried to mislead me or cost me money. I am smart enough to make my own decisions based on the opinions and advice this site generates. We are a competitive bunch. The power struggles playing out on this site can be entertaining from time to time. However they are becoming more frequent and personal. The site will lose some of what makes it so great if it persists. Just my crusty 2 cents :badrain:
 
Status
Not open for further replies.
Back
Top Bottom