PICKINI V4 - an easy to build, self adjusting PI detector

[Tim]

Perhaps George or Ivconic or other knowledgeable persons here could make some op-amp/front-end design suggestions? I would dearly love to see more here at Geotech regarding small gold, and brutal mineralisation, as opposed to relics, coins, and deep stuff in "easy" ground.......??
The only things I have found here truly relevant to gold, is the ancient Goldmaster schem, and Lobo. As far as mineralisation, 2 samplers like HH, Goldscan, Pulse1&2, limited stuff on the Mirage. The SD2000 is a pipe dream for all but the most dedicated and learned.
Perhaps there is a way to incorporate temporal sampling, and a multiple ground samples (a-la Hammerhead) to "punch through" the hard ground?
Food for thought?

Thanks for this F117. I have my pics. Now awaiting the pickit on the slow boat from China.

[ivconic]

These are good guidelines, post #63:
http://www.geotech1.com/forums/showt...Settling/page3

[Tim]

Yes, thanks Ivconic. I have read this and much other theory and testing...So... Looking at 500-1000hZ, 100-160 pulse width, 6-10uS Delay-for a single-sample. I have read the on-time etc. for double samples, and checked the scopics of the SD2000.(Although I don't know these off by heart).
But which of, and how, can these specifications be related or utilised in a temporal domain detector?
I have seen cut-and-shut designs here, and realise many of your masterpieces utilise sections from previous designs. Everything old is new again.
Basically I would like to see enough interest here to stimulate F117's request to optimise the front end.

Some ideas that may or may not float.
Op-amp change.
Variable offset on op-amp.
Comparator reference adjustment.
Maybe the two 74HC221 circuits from the Hammerhead can be adapted as secondary and tertiary delay? One through RC3/pin7?

Please don't laugh at me.

[F117]

@Tim & Ivconic: thank you for all the extra inspirational thoughts !

Variable offset on op-amp.
Comparator reference adjustment.

These 2 are now implemented in the Pickini V4 version.
The comparator slicing level ( reference ) could be a potmeter 0..5V if you wan to have full manual control and like fine tuning.
No idea if this will be useful in a highly mineralized environment.
Also: is there any difference when measuring the pulse width between a slow coil and a very fast one ? ( eg. 10 microseconds vs 100 microseconds )
The temporal change should be far less with a fast coil, but still detectable with a high resolution timer like this ?

I was under the impression that temporal sampling would be less coil dependent than delayed voltage sampling since everything is relative, independent of the absoulute pulse width.
The closer the pulse width can be measured to the steady state value, the more sensitive the detector.

Best regards,
- Bernard

[Tim]

So the faster the coil, the faster the natural delay will be? And higher the sensitivity will be able to be adjusted??
I am very eager for my pickit to arrive. This sounds like a great project.
Yes effect of comparator level will be interesting. How about RC3/pin7? Can we utilise this for another sample input?
More food for thought Bernard.

[eclipse]

While waiting for the parts to arrive I tried to play with the firmware a bit.
I used MikroC 6.6.3 (latest) to compile the source. It compiles without errors however the hex file is not the same as the original.
Perhaps some setting in Project/Edit Project Menu is different?

[Arionas]

[eclipse]

Errr... I'm pretty sure cracking the software won't make a difference.
It's probably due to different project settings.

[F117]

Here are my project settings:

[eclipse]

That helps a lot Bernard!
I made my configuration registers match yours.

Still hex has some differences but I loaded in Proteus and looks to be working fine.
Probably some internal compiler differences (maybe?!) give somewhat different results.

[F117]

I use MikroC Pro 5.61 as compiler.

Why are you trying to recompile the source code to match the exact binary/hex output ?

You can use the source code as a reference to change some things.
Or - you just take the hex file as is and program the PIC.

Best regards,
- Bernard

[eclipse]

I wanted to make few changes (inverse TX polarity, slightly increase pulse width).
With the help of the correct project settings I'm sure the changed hex will be working just fine.
Here's my board. It's 80x45 in size, few cosmetic changes here and there to fit parts I already have.

[F117]

Nice work !
I assume that the extra chip IC4 is a FET driver ?

Looking forward to seeing the complete stuffed board in action.

- Bernard

[eclipse]

Yes instead of the BS170 & 3 resistors there (I kept R13/10R) I will have MCP1407, since I have those from previous builds.
I needed to inverse the TX signal because otherwise I would need to use inverting chip which I don't have.

[Tim]

Okay, I got my pickit 3 today. Downloaded MPLAB v8.92. It was a zip file. Eventually and tentatively I unzipped it and double-clicked the Setup wizard. I have installed it, but unsure if I did this properly. Got shortcuts and windows, usb recognises pickit unit. But all the files from the zip are still in downloads. Can anyone tell me where they should be, or if the install will have put them(copies) where they should be?
What do I do next?
I searched for hours online, and nothing back to these basics, and the rest is gobbledigook. I have 3 PDF versions of instructions-all mean nothing to me. Much talks about de-bugging, and all I want to do is program the bloody chip. But I have no idea where to start.
Any advice greatly appreciated- no acronyms please.