different pi detectors?

[Anonymous]

I have resisted asking so I could educate myself, but after days of searching and reading, I need your help. I can't seem to grasp pi technology.
What is the difference between small pi detectors (like Tesoro's sand shark) and a Lorenz or Pulse Star deepseeker? Can a larger coil be adapted for smaller detectors for deepseeking? Or are we talking apples and oranges? Thanks for being patient with me

 

[Anonymous]

<center><a href="http://www.surfscanner.com"><img src="/metal/html/s-s.jpg"></center>

 

[Anonymous]

Elementary, my dear Watson. So my question still begs an answer. Can I build a 40 in square search coil and apply it to <FONT COLOR="#ff0000">any</FONT> pi detector? Some mfgs sell a pi for a few inches of depth, while others sell for cache hunting. Is the only difference (besides the mfg's name just the size of the coil itself? If they're all the same, then why does one sell for $500 and another for several thousand?

 

[Anonymous]

I think that most of the large coil cache detectors usually have a minimum pulse delay that is much longer than on a coin/ring type detector so you would need to understand that you would have to turn the pulse delay or "reject" control up some for the large coil to be usable on a coin ring detector. Most likely, if you build a large coil to use on a coin/ring detector, you will have to go inside and play with the size of the damping resistor depending on the inductance of the original coil versus the inductance of the large coil.
Going the other way around. You could buy a large coil cache detector and put a small coil on it but most of them have a minimum pulse delay that is much more than the desired 10 to 15uS of a coin/ring detector so your performance would suffer. This would mean that you would need to have some means to lower the pulse delay. A resistor change on an analog detector or reprogramming a PIC or other processor on a microprocessor controlled detector. Also, again you would most likely need to adjust the damping resitor as they are often overdamped on the large coil cache detectors since the minimum pulse delay isn't critical for their intended use.
Good luck,
FJ

 

[Anonymous]

Darren
Sorry for being so vague. <img src="/metal/html/shrug.gif" border=0 width=37 height=15 alt=":shrug">
I doubt you could apply it to "any" PI detector, and I doubt the Tesoro would perform well with a 40" coil on it. A unit like the Tesoro would most likely have it

 

[Anonymous]

Hi Darren,
Generally speaking all PI's are relatively the same in how they operate. They pulse the coil with a brief pulse, wait a short time after the pulse is turned off and then sample the receive signal.
Some PI's use more pulse current than others. Some may use a longer pulse duration. Some will allow a sample to be taken after a very short delay, while other PI's will not. Some PI manufacturers shield their coils, while others do not. All of the above items depend upon the application of the PI and the desired results.
If one is going to look for large iron relics then a large coil and a long delay would most likely be the best combination. There will also be little need for a shielded coil.
However, if one is going to look for small gold objects, then a smaller shielded coil and a very short delay would be a much better choice.
As for your question of whether a larger coil could be adapted to one of the "smaller PI's", the answer is yes, providing the PI allows for adjusting the delay over a fairly wide range. Whether it would be just as efficient or as sensitive as another PI, specicifically designed to use the larger coil is another matter. My guess is it would be reasonably close, but there would be a difference.
A large coil will generally require the delay be longer for proper operation.
I hope this helps a little.
Reg