Pinpointer with tone discrimination Metaldetector

Everyone,

Here is a photo of my finished pinpointer. Testing will bgin tomorrow.
Dusty Carl

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A bad day at gold prospecting or metal detecting is better than a good day at work.

That's a possibility. Thanks

Dusty Carl

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A bad day at gold prospecting or metal detecting is better than a good day at work.

A standard 9 volt snap battery. It fits in the handle. Case is 1 inch schedule 20 (or class 200) for handle and 3/4 inch schedule 20 (class 200) for the board and rod. Inside diameter of schedule 40 is too small. Don't know how that translates to products in foreign countries.


Dusty Carl

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A bad day at gold prospecting or metal detecting is better than a good day at work.

		Quote:			Posted by homefire
	Did you put a O ring in the joint of the PVC?

No. When this type of reducing coupler is pushed tight, it is almost impossible to get it off without a vise and hammer. It is internally tapered. You can use pvc glue if you want to seal it permanently,  but I  wouldn't. What if you ever want to reprogram the chip with an update?

I have done some initial testing. I buried a penny at 4 inches in regular dirt in the front yard. After removing some soil, the probe began detecting it at 3 inches. About the same for my Vibraprobe. Was surprised to see that it detected very large targets at 8 inches. My Vibraprobe does not do that. Due to that sensitivity, I  will do the rest of my tests outside. Next test up? Thermal stability . It is cool and overcast now but will get sunny later.

Dusty Carl

Posted on: April 26, 2015, 12:11:19 pm

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Ok, an hour outside. Left turned on unattended. Ambient temp increased 3 degrees. Probe stable. Next test: disassembled on bench for actual drift measurement test with temp probe, oscilloscope, and variable heat/cold source. One problem noticed so far. If probe is brought near a large object, it will overload and continue to buzz after taking it away. Have to push reset to get it to stop. Software might have a never ending loop somewhere or watchdog timer being ignored. It is turned on in code.

Dusty Carl
 

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A bad day at gold prospecting or metal detecting is better than a good day at work.

		Quote:			Posted by homefire
	Yep Magnetic Switch could be the ticket.  Old Key Boards had reed switches less then a 1/4 inch.   A slidable Magnet on the out side would do the job.  Neyembiums are far better then when the key boards were in use.

Thanks for your suggestions. Don't have any of the really old keyboards though. I am working on some other  designs for this circuit. I bet I  could use it to detect aliens! 

Dusty Carl

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A bad day at gold prospecting or metal detecting is better than a good day at work.