Pinpointer with tone discrimination Metaldetector

There are a lot of modification I see in this MetFM2 as long as we have the source code, now what i have to do
is trying to convert the hex file in asm. from the power reg. you can use 78L05, LM317 or even LD1117.
I order my 675 in here;

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   How does this thing work?    I see a resonant Circuit on the coil.    Feeding back to the Brain.  The Brain is being clocked at 20Khz.  Is it just doing a Digital version of a BFO?

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		Quote:			Posted by homefire
	How does this thing work?    I see a resonant Circuit on the coil.    Feeding back to the Brain.  The Brain is being clocked at 20Khz.  Is it just doing a Digital version of a BFO?

Could be BFO. Might be just measuring a direct frequency or phase change. The brain just takes the 20 MHz in and divides  it by 4 to run things at 5 MHz. There are 3 timers (0-2), but I  doubt if he is using 1 of the timers. More like using interrupt on change.

Dusty Carl

Posted on: April 12, 2015, 09:37:45 am

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		Quote:			Posted by xavier
	Why are you saying that? one pin of the crystal is on ground and the other on base of T4

Yes that is correct Xavier. T4 and the xtal and associated parts form an external oscillator. I was asking by what Homie meant when he asked about  2 pins . Was he referring to a 2 pin xtal or was he suggesting using the 2 pins of the 12F675 (pins 2 & 3 clkin & clkout) to hook the crystal to such as in the second drawing. Since I  had been talking about the first drawing before, it would take software changes to implement that and we only have the hex file to work with. Hope my long winded explanation wasn't too confusing.

Dusty Carl

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

[ author=xavier link=topic=60126.msg295036#msg295036 date=1428860988]
Now you have lost me. We have the schematic and PCB layout with components placement, this project should only take a few hours to complete once you have all the components.
[/quote]

Didn't mean to confuse you buddy. Going way back, sinclairuser mentioned using the circuit say for a full size md, and you mentioned building it on vero board. Well with those ideas in mind, and since Homie is also building on vero board, a clock oscillator is an easier way to go. Low cost, low real estate requirements, stable, low current draw and low parts count.
What's not to like? I just bought 5 for $3.99 US. 80 cents each. I know true kit builders like to stick to original designs, but is the original design as good as it gets? It's true you would have to change the pc board layout, but if a person has the equipment to make pc boards, then there should be no problem modifying the layout. Now if one uses a third party to make his boards, then he probably stick to the plans. Another long winded explanation.

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 xavier
	OK but Homie got two left hands when it comes to PIC's and anything that looks digital so are you going to make him a new PCB?

I think Homie is smarter than he pretends to be. I woul be glad to make him a board if he asked me, but i no longer have a way to make them. So, it's vero board for me too. I think he could do it, and if he ran into problems, he could always get help here.

Dusty Carl

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