Universal PI Micro

[bugwhiskers]

Maximising sensitivity

To maximise sensitivity it is recommended that all the sample and hold capacitors be polypropylene types and the muxes be the MAX405x family due to their better leakage figures, 10 times better in fact than the standard 405X or 74HC405X series.


regards
bugwhiskers

[bugwhiskers]

Correction

Correction to the above post, I meant to say the MAX405xA family. The "A" suffix denoting the premium parts with better specs. They are not cheap nor readily available but worth the effort as the voltage at the threshold of detection is miniscule and can easily bleed away via chip/cap leakage.

regards
bugwhiskers

[Unregistered]

Hi there,
This thread has gone very quiet. Has there been any progress or has it gone underground?

Interested bystander.

[Unregistered]

Hi there,
This thread has gone very quiet. Has there been any progress or has it gone underground?

Interested bystander.

Bugwhiskers now mostly only posts on a new forum:
http://goldprospecting.invisionplus.net/
Well worth a look at this forum,a lot of good electronic and other stuff both for members and guests.

[Unregistered]

Thanks DOUG

[amtech2005]

Universal PI Micro

I DID CHECK OUT THE http://www.goldprospecting.invisionplus.net AND ITS A GREAT NEW SITE WITH ALL ITS NEW ELECTRONIC DESIGN TOPICS OR THREADS. BUT SOMETHING IS MISSING AND ITS BIG !!!! SO I WILL START A NEW THREAD HERE ON GEOTECH THAT WILL HELP A LOT OF PEOPLE INCLUDING MYSELF . AND IT WILL BE A TOPIC THAT IS NOT COPIED FROM ANY OTHER FORUM. IT WAS SOMETHING I WAS TRYING TO START 3 OR 4 YEARS AGO AND NEVER GOT AROUND TO IT. YOU WILL SEE IT TONIGHT OR TOMORROW. IT WILL BE NAMED SOMETHING TO THE EFFECT OF "I.C." [INTEGRATED CIRCUIT] APPLICATIONS FOR V.L.F AND P.I. METAL DETECTOR'S. I WILL EXPLAIN WHAT I AM TRYING TO DO ON THE FIRST POST...............EUGENE

[amtech2005]

Universal PI Micro

Where is bugwhiskers ?? Did he ever complete his PI MICRO Metal Detector ?? I will go through all the posts here again and try to refresh my memory , if he posted all the complete final schematics and software , or if his P.I. Micro metal detector is only for sale , and not for us to build ?? This post went dead Quick !!!..........Eugene

[Sean_Goddard]

Hi All, just "re-found this thread".

BW I'll take one of those when it's finished. I suggest a PAYPAL account and website so that we can buy directly from you .

I assume the reason for the 64 caps is that the Atmel A/D is not fast enough to directly sample the decay, so you are "retiming" the waveform and using the blanking period between Tx pulses to do the processing? Or am I just being an idiot (again) and missing something else?

In the mean time, Can I suggest these;

http://www.cirrus.com/en/products/pro/detail/P1024.html

You can interleave left and right channels and sample at a whopping 384KHz with inherent 120dB s/n. Talk to J.L. King about this IC I sent him one to evaluate.

Instead of the 64 stages why not use 2048 in a BL3208A (or similar) Bucket Brigade Delayline??

If you don't need all 2048 stages I have an idea. Say for example that you only need 128 samples, then what you could do is take your 128 at say 11Ms/s then ground the BBD input (to reduce noise) and "up" the clock frequency to, say 5MHz, "race" the data through the remaining unused stages until the wanted data was then near the output pin (near in terms of number of internal caps to traverse). Then simply drop the clock frequency to match your required A/D sample rate and hey presto, you can accurately digitise the decay curve.

You could also use a television CCD device (stores one line of analogue video) as these things are meant to work REALLY fast (around 5MHz)

If you did the timing circuit in an FPGA ,then you could experiment with different sample rates and number of samples taken very easily.

Of course the above may not be what you want to do, but the BBD is just a small DIP8 instead of a bank of 64 caps and takes up a LOT less space in board real estate.

Hope this gives you some ideas.

GREAT project BTW

[Sean_Goddard]

Apparently not everyone is driven by greed. I've followed BW's threads with great interest as it appears to be one of the most superior projects here. What disapoints me is that status is not merited by intelligence but by favouritism. It's blatantly obvious that this guy knows more about ee than most that post on this site. I have no doubt he's capable of a design that matches or exceeds any commercial design made.

I will agree there are freeloaders lurking about but I also see lots of "wannabee's" with little to no knowledge. If the commercial project can come up with anything even close to this design I'll be happy for them but at the same time extremely surprised.

IMO

And you are WHO now? Could YOU do better?

I think you serisously underestimate some of the people here. Yes a lot of ideas are thrown around, so why not sign in with a REAL name and join the debates constructively instead of just passing semi snide remarks and hiding behind anonimity? that smacks of a UKDN member (= BIGTIME, know nothing LAMER ) to me.

Yes BW's project is VERY promising, but as you can see a few others have thought about and recognised what he is trying to achieve, and suggested more technical and effective ways to get the same results and as for favouritism, that's just plain BS. A few post regularly anad ALL are welcome, there is no discrimination of favouritism here that I am aware of, Carl ensures this. Please cite examples.

Not ALL of us have the time to do as much as we would like. If I didn't have to "work" to pay the bills, then MAYBE I could be churning out projects like this or, more likely, I'd just be drunk in the corner of a bar somewhere, still we all have our crosses to bear.

[Sean_Goddard]

Every one here seems to be a nut case mumbling to themselves, just like a cpu talking to ram without any proper output, with their clone schematics, try to get to the front end circuitry you fellows. Just changing the display with graphical one and cloning the hardware wil not help you fellows, since year 2000 i am seeing this site, and no improvement, many 2nd grade manufacturers in India has a PI detector which can detect a cannon ball 5 feet away in air, you fellows dont even come to this limit, and you cant come to the speck of 20 feet detectors....

SURE I CAN!!

I could pulse 200+ Amps through a coil and detect a cannon ball at 40feet plus, but why would I want to do a lame thing like that? Moreover Why would I want to dig 20ft for a cannon ball?

You're talking bovine faecal matter mate. Have some constructive input or shut up and shove off..troll!

[Sean_Goddard]

Whats assembly going to do ..use c program, its standard and easy, and run the micro at max spped ie 40-80Mhz, c avoids complex prog patterns and helps in seeing interrupt latency and delays.

Yes and you're no programmer either!!!

Use C?????????? WHOOP DE DO....OMG!!!! In what way can you even PRETEND to accurately control the timings of loops down to uS with a C compiler that produces code bloat and thus timings in days rather than uS?? Sorry dude, but it's ASSEMBLER every time for an app. like this. If you have ANY embedded experience you would know this simple fact.

Q: What are C's LOW LEVEL (direct hardware) drivers written in??

A: ASSEMBLER..10 points if you got that one (which you didn't).

And as for implementing interrupt service routines in C, the same applies. they need servicing NOW, not when the compiler decides to put in the code with associated delays to say "anytime this week will do".

Amazing just how all these "know it alls" with nothing to say except criticise and pass snide comments hide behind the "unregistered" tag.

No wonder poor BugWhiskers left this forum, all the trolls asking him stupid questions when they should read the whole thread. "The answer is out there" to quote the X-Files

[Atul Asthana]

Assembly is the way to go

I agree with Sean for use of assembly.
Though a little tough, assembly gives you the control and flexibility. And, a large amount of libraries are available for AVRs, on the web to reduce your burden.

[Tinkerer]

assembler

Yes and you're no programmer either!!!

Use C?????????? WHOOP DE DO....OMG!!!! In what way can you even PRETEND to accurately control the timings of loops down to uS with a C compiler that produces code bloat and thus timings in days rather than uS?? Sorry dude, but it's ASSEMBLER every time for an app. like this. If you have ANY embedded experience you would know this simple fact.

Q: What are C's LOW LEVEL (direct hardware) drivers written in??

A: ASSEMBLER..10 points if you got that one (which you didn't).

And as for implementing interrupt service routines in C, the same applies. they need servicing NOW, not when the compiler decides to put in the code with associated delays to say "anytime this week will do".

Amazing just how all these "know it alls" with nothing to say except criticise and pass snide comments hide behind the "unregistered" tag.

No wonder poor BugWhiskers left this forum, all the trolls asking him stupid questions when they should read the whole thread. "The answer is out there" to quote the X-Files

Thanks for your post. It makes me feel a lot better with my feeble attempts at getting the timing right.

Tinkerer

[Sean_Goddard]

OOER....I hope you don't think I was having a "go" at you Tinkerer . I know your skillset outclasses mine in so many areas, no really I MEAN that. I have the greatest respect for you. Having read many of your previous posts.

The unregistered post I saw seemed to be telling BW that he didn't know what he was doing it, and it kind of hacks me off that some are all too ready to point out problems without providing suggestions as to answers. I used to do it until someone pointed out that is was just NOT the "done" thing. Now at least I'm aware when I'm being an *** (mostly).

I have been coding MC (machine code) since I was 13 years old (I used to write SW in HEX for the ZX Spectrum) although I gave it up and now use compilers myself.

Took me ages to work out why my critical timing stuff didn't work when written using compiled C and the like. Turns out I'm not as smart as I thought I was . You learn something everyday eh?

[Tinkerer]

writing assemby

OOER....I hope you don't think I was having a "go" at you Tinkerer . I know your skillset outclasses mine in so many areas, no really I MEAN that. I have the greatest respect for you. Having read many of your previous posts.

The unregistered post I saw seemed to be telling BW that he didn't know what he was doing it, and it kind of hacks me off that some are all too ready to point out problems without providing suggestions as to answers. I used to do it until someone pointed out that is was just NOT the "done" thing. Now at least I'm aware when I'm being an *** (mostly).

I have been coding MC (machine code) since I was 13 years old (I used to write SW in HEX for the ZX Spectrum) although I gave it up and now use compilers myself.

Took me ages to work out why my critical timing stuff didn't work when written using compiled C and the like. Turns out I'm not as smart as I thought I was . You learn something everyday eh?

Sean,

writing assembly code is a painfully slow process for me. But I have found nobody to do it for me so I have to bite the bullet.
People tell me I should learn C that is easier. Or C## or what not, well there just are things that one is too old to do.
Today I managed to have my PI with PIC timer running just exactly the way I wanted.
Exactly 10,000 PPS
5 different samples of 5us each at exactly the right time.
Blocking the flyback at exactly the right time within 1\2us in spite of the analog delays caused by the transistors.
First sample taken at 5us with a gain of 2000 on the preamp. 320mA coil current.
So I felt reasonably good, just that nagging thought:"got to start learning C"
So when I saw your post, it really made me feel better. For somebody with the vast experience like you to say that assembly has its merit and that a lot can be done with assembly has made my day. Thank you.