Posted by Reg
on 7/2/2009, 11:40 pm, in reply to "Reg, I was hoping you would respond."
76.25.124.194
Hi Mike,
One really needs the schematic to assure the correct design is implemented properly. The GQ or even an older C Scope 6PI is a good candidate. (I have picked up a 6PI quite reasonable in the past so I know they are out there.) It just takes time to find one. In any case, the additional circuitry also requires a different housing to enclose everything.
Now, the ideal way is to try to find a used TDI or a GS 5 at a good price. Earlier GS 5's can be converted to the single tone feature quite easily so if a person can find one of those it would work too.
The tone feature works best on the higher powered PI's because they simply go deeper because of the increased power involved.
The low powered PI such as the GQ is a good gold machine but the low power isn't the ideal setup for hunting for the older silver and copper coins. Both silver and copper really require a longer pulse signal to obtain the best results.
The shorter pulse length of the GQ works extremely well for gold objects in the typical jewelry size and smaller. This is why it is so popular and works so well on the beaches. Also, beaches do not require a form of ground balance (GB) as a general rule.
Any form of GB will reduce the sensitivity. However, I had been toying with the idea of coming up with a little different design that would allow the use of no GB for depth, but use the GB circuitry to develop a tone system. This would allow for maximum depth and still provide some unique target separation. Unfortunately, that design hasn't been fully developed yet.
Now, I really do not like the idea of trying to implement this concept on a probe. What I have found is strange things happen with probes. I have one I use with my TDI and switching to it doesn't always give me the signal I would expect. I am not sure why either. Since it isn't a major problem, it isn't high on my list of things to figure out.
Reg
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