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SandShark Pulse Width Adjustment

A

Anonymous

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I have a Tesoro SandShark and I was wondering if adjusting the Pulse Width is a change in the frequency in uS. I understand that 10uS is the best for gold and if you get up around 15uS you could miss the gold and it could be silver, copper, iron or any numbers of other metals. According to the manual, increasing the Pulse Width increases the depth and sensitivity. It appears to me that if you increase the depth you would loose the sensitivity to gold. If this is true, does anyone know what the high and the low Pulse Width adjustment in uS on my SandShark? Am I totally missing something here? Thanks!!!
 
Randal,
I have been looking at the Sandshark myself.
I believe (and I could be wrong) that the adjustment is for transmit pulse length, or frequency. That would explain the battery drain at higher settings.
What I would appreciate hearing from someone is how the sampling delay on this machine compares to others as it appears from all the technical posts here that that is perhaps more important to sensitivity to small gold. Maybe DJ knows and could answer?
The price sure is right for a waterproof machine.
Tlom
 
Randal et al:
Although I used to work for Tesoro at one time, I wasn't involved with the PI units, and so for that reason know almost nothing about them.
If I had been involved with the PI units, I would have to protect trade secrets (if any) related to them.
From other posts here about the SandShark, I get the impression that the pulse control on the SandShark varies transmit on-time duration, but not any other part of the whole sequence. This would preserve sensitivity to small targets. The maximum settings would give best sensitivity to large targets and iron, but at the price of higher power consumption.
If it is set up to vary only the transmit on-duration part of the sequence, the total sequence time varying along with it, then this control might also be useful for minimizing electrical interference. If the total sequence length is fixed, this benefit would not accrue.
Since transmit power consumption and electrical interference are such prominent concerns in most PI topologies, this would seem to be a worthwhile feature to offer.
--Dave J.
 
The SandShark pulse width control only varies the TX on time. The sample delay is set by the PIC microcontroller and can only be changed in code (i.e., not at all). I've just finished probing out the SS front-end circuitry and timing, will post if anyone's interested.
- Carl
 
Me 2. I am interested in seeing the front end, Dave. * * *
 
Simple answer is that as you vary the TX pulse width, you allow a greater magnetic field to build up in the coil.
Sure, you'll get better depth, as you're punching out a much heftier signal, nad thus penetrating deeper, BUT, you'll kill your batteries in a much shorter period.
 
If the person who posted the CCT diagram of this machine, would care to complete it, I'm working on a modificationusing a trimmer and a small PCB which fits into the SS case, and lets you tweak the sample time.
The system will need a new PIC as the internal program is different.
Cannot procede without complete CCT diagram.
 
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