Another coils for Relic Hawk?

[Eugene52]

Another coils for Relic Hawk?

Hello Sean and everyone , yes many things can be done for noise and RF shielding . And also if we learn to identify and isolate the source of noise , we can create a test procedure for the PCB board before the components are soldered on !!! I mentioned this before on the Golden Sabre "Thread" !! Any Final circuit board design "must" be tested for noise before the components are mounted . And the software used , should have carefull "ground Trace placement" in regards to signal path , supply voltage. Maybe later on down the road we will get into solving these pesky noise problems , a new geotech thread can be called "circuit board noise reduction" under the modifications thread . we can isolate , eliminate all self oscillations or shield the circuit from external RF, and also throw in a few oscilloscope photos......Just an idea ................Regards..........Eugene

[Sean_Goddard]

OK for what it's worth I suggest the following;

1) First off a SYNCHRONOUS DC-DC converter for generating both POSITIVE and NEGATIVE power rails. If it is driven so the flyback of the Tx is used to genarate the voltages, then the noise can be "made" to be in the non sampled (5uS) region of the Rx signal. This will help a LOT.

2) LOTS of filtering in both +ve and -ve rails (with circuitry to remove common mode noise too).

3) HEAVY traces on the PCB which will be a FIVE layer board. Layer 1 and 5 are ground but ONLY commoned at ONE point (star ground). Layers 2 and 4 are signal and layer 3 is Positive rail (layer)

4) THREE boards. Tx, Rx and Audio (including motion circuitry etc).

5) NO sharp angles on PCB, all corners are radiused. All signals on different layers cross at 90 degrees to minimise coupling.

6) ALL large signal areas are FULLY screened using cans and chained vias through the board and are as far as possible from low level signal areas if on the same PCB

7) Input / output impedences of each stage is matched, as are is the characteristic impedence of the tracks.

Low noise amps, metal film resistors and polystyrene caps to be used throughout. Avoid high value electrolytics, they are as noise as hell unless you buy "audio grade" and these can cost over $40 each!!

I think that might be a good start. If I've missed anything off that please feel free to add a few suggestions (polite ones only please).

Of course the PCB will be the most critical for this so we need a VERY good PCB designer, I'm afraid that's NOT my area of expertise..Anyone???

[Eugene52]

Circuit Board Noise Reduction

OK for what it's worth I suggest the following;

1) First off a SYNCHRONOUS DC-DC converter for generating both POSITIVE and NEGATIVE power rails. If it is driven so the flyback of the Tx is used to genarate the voltages, then the noise can be "made" to be in the non sampled (5uS) region of the Rx signal. This will help a LOT.

2) LOTS of filtering in both +ve and -ve rails (with circuitry to remove common mode noise too).

3) HEAVY traces on the PCB which will be a FIVE layer board. Layer 1 and 5 are ground but ONLY commoned at ONE point (star ground). Layers 2 and 4 are signal and layer 3 is Positive rail (layer)

4) THREE boards. Tx, Rx and Audio (including motion circuitry etc).

5) NO sharp angles on PCB, all corners are radiused. All signals on different layers cross at 90 degrees to minimise coupling.

6) ALL large signal areas are FULLY screened using cans and chained vias through the board and are as far as possible from low level signal areas if on the same PCB

7) Input / output impedences of each stage is matched, as are is the characteristic impedence of the tracks.

Low noise amps, metal film resistors and polystyrene caps to be used throughout. Avoid high value electrolytics, they are as noise as hell unless you buy "audio grade" and these can cost over $40 each!!

I think that might be a good start. If I've missed anything off that please feel free to add a few suggestions (polite ones only please).

Of course the PCB will be the most critical for this so we need a VERY good PCB designer, I'm afraid that's NOT my area of expertise..Anyone???

Sean , Excellent response !! Many good suggestions . On this noise subject , I should have started a new thread , away from this search coil thread !!! Anyway , If a cloned "new" metal detector circuit board is copied from an old perfect working machine and there is now noise present , and If the circuit board has different demensions and trace locations than the original . WE know it is the copied pcb board that is creating the noise problems !!! ..Sean did you ever field test your excaliber-1000?????.........Regards.....Eugene

[Sean_Goddard]

Hi, Nope never got that field test done .

Oh I forgot, GUARD RINGS around ALL op-amp inputs AND outputs with ceramic resistor standoffs to inputs. FINALLY, whole board ultrasonically cleaned in isopropyl alchohol then baked for 24 hrs at 80 degrees C (to drive out moisture). Then conformal coating (enviromental sealant) applied to seal out contaminants and thus keep predicted values true.

Oh, PTFE PCB material might help too, NOT usual F4 or Rogers. Bear in mind PTFE is hygroscopic and thus it's impedence changes in damp weather!!

[ivconic]

OK for what it's worth I suggest the following;

1) First off a SYNCHRONOUS DC-DC converter for generating both POSITIVE and NEGATIVE power rails. If it is driven so the flyback of the Tx is used to genarate the voltages, then the noise can be "made" to be in the non sampled (5uS) region of the Rx signal. This will help a LOT.

2) LOTS of filtering in both +ve and -ve rails (with circuitry to remove common mode noise too).

3) HEAVY traces on the PCB which will be a FIVE layer board. Layer 1 and 5 are ground but ONLY commoned at ONE point (star ground). Layers 2 and 4 are signal and layer 3 is Positive rail (layer)

4) THREE boards. Tx, Rx and Audio (including motion circuitry etc).

5) NO sharp angles on PCB, all corners are radiused. All signals on different layers cross at 90 degrees to minimise coupling.

6) ALL large signal areas are FULLY screened using cans and chained vias through the board and are as far as possible from low level signal areas if on the same PCB

7) Input / output impedences of each stage is matched, as are is the characteristic impedence of the tracks.

Low noise amps, metal film resistors and polystyrene caps to be used throughout. Avoid high value electrolytics, they are as noise as hell unless you buy "audio grade" and these can cost over $40 each!!

I think that might be a good start. If I've missed anything off that please feel free to add a few suggestions (polite ones only please).

Of course the PCB will be the most critical for this so we need a VERY good PCB designer, I'm afraid that's NOT my area of expertise..Anyone???

Mmmmhahahhahahahahahahaaa...hah...hah!!!
Sean...you are hard to beat - no doubts!

What you named here is list of conditions to make a PERFECT design...which is in most of cases almost impossible! Pitty!
Not that i only agree with you ..but for real i A G R E E with all what you listed above!
But must admit - it is very hard to achieve and to comply all the conditions.
Refering metal detectors...we must agree that size and shape of pcb is usually restricted hardly due fact that md is mobile/handy device and must comply many objective conditions; lightweight,small as possiblle etc...etc..
Only solution is smt to close up to demands.
Other hand; majority of DIY'ers here (including myself) are not in position to adapt and work in smt area at all...pitty.
So what left to us? Just to try hard to close up our work as more to those conditions. Very hard task!
Yet not enough resons to give up - for sure.
Drawing few TGSL pcb's in Sprint Layout i had on mind all you listed above...but must admit that my final draw is a way out of descent design.
If i obey one - i must "sin" other rule from the list.Damn!
Very hard to achieve.

[Sean_Goddard]

Yes but we TRY and that's what counts.

A few "sins" can be forgiven, but we can get close to perfect maybe close enough. Look at Tesoro's PCB's so badly done it's unreal, yet they work!! YES they could be better. I suggest taking say the Silver Sabre, or your TGS lite as a starting point and applying the simple stuff like guard rings and running ground lines as close as you can get in PARALLEL to the small signal lines (making like a coax if you can see what I mean)

--------------------------------------------------GND
____________________________________________signal
--------------------------------------------------GND
Equal spacing both sides of course

Keep the Tx in a corner of the PCB and isolate everything (ground lines included) using ferrite beads and decoupling caps. Use VERY heavy decoupling on the output comparators (393's) and decouple the wiper of the sensitivity potntiomenter with a 220nF to the star ground (oh yes, Star ground, this is HARD but CRITICAL). I think all this will give BIG impovement.

Oh, forgot, put Rx amp on OPPOSITE corner (imagine rectangular board, then Rx is diagonally opposite) of the PCB.

------------------------------------------------------
|TX CCT
|
|
|
|
|
|
|
| .................................................. ..............RX CCT
|------------------------------------------------------

That's why top PCB designers earn $100 per hour

[Unregistered]

Max on Mars ??

Hi Max and Elie ESA has identified an extra terrestrial cloaca specially for euro people has opened from other dimension jump in very fast, the time window is very narrow

Max is on mars tunelled thru the cloaca, the british military helped him push thru the cloaca to get into another world but due to some software glitch by gates microsoft, he landed on mars

with the recently leaked UFO documents by british military they have kept this Max issue a secret.

Elie is still stuck up in the cloaca due to software glitch by gates microsoft, the body welded thru the cloaca similar to hutchison effect

[Sean_Goddard]

ROFLMAO

[Max]

Max is on mars tunelled thru the cloaca, the british military helped him push thru the cloaca to get into another world but due to some software glitch by gates microsoft, he landed on mars

with the recently leaked UFO documents by british military they have kept this Max issue a secret.

Elie is still stuck up in the cloaca due to software glitch by gates microsoft, the body welded thru the cloaca similar to hutchison effect

Your problem is that you were born in a cloaca, not my fault!

Apart your childish complain here I see no useful post by you... about your 555 experiments on some dead MD project... sure you need a uA709 but you'll not find at your "advanced" country.

Anyway, you , at least, do not need any time/dimension travel to get where you already are. Good for you!

Now I'm a bit... well... distracted by very serious affairs and troubles, I have no time to pi$$ you off more than this for now...

But I will return from "Mars" and will hit you in the back as before, then you could also pray having a stargate inside your outhouse, just to change planet.

Sorry , you must wait a while and perform some new visual basic pearls in my absence.

Kind regards,
Max

[Unregistered]

max and maxi

Your problem is that you were born in a cloaca, not my fault!

Apart your childish complain here I see no useful post by you... about your 555 experiments on some dead MD project... sure you need a uA709 but you'll not find at your "advanced" country.

Anyway, you , at least, do not need any time/dimension travel to get where you already are. Good for you!

Now I'm a bit... well... distracted by very serious affairs and troubles, I have no time to pi$$ you off more than this for now...

But I will return from "Mars" and will hit you in the back as before, then you could also pray having a stargate inside your outhouse, just to change planet.

Sorry , you must wait a while and perform some new visual basic pearls in my absence.

Kind regards,
Max

our max was dropped on floor during his birth. now he's under a maxi. MD's are not dead, they have been getting new design or cloning with out any improvements with different IC's. CA3130, 3140 and LM709 etc etc are made during 1980's, and still we are using them in the world. having mobiles and sapce programmes and some business software doesnt seem to make a country advanced and it applies to other countries too apart from India, what max does is copy and paste from the Internet, critisizing is a very tedious and intilligent artwork, DO U Understand MAX

[Max]

our max was dropped on floor during his birth. now he's under a maxi. MD's are not dead, they have been getting new design or cloning with out any improvements with different IC's. CA3130, 3140 and LM709 etc etc are made during 1980's, and still we are using them in the world. having mobiles and sapce programmes and some business software doesnt seem to make a country advanced and it applies to other countries too apart from India, what max does is copy and paste from the Internet, critisizing is a very tedious and intilligent artwork, DO U Understand MAX

I understand you're bronken from inside!

Aren't you that need an MD that detects diamonds ?

Which kind of metal is a diamond ?

But maybe using a CA3140 you'll solve your problems , eh ?

And what if rubbing it with some eye cream and $hit of camel ???

You need a serious psycotherapy!

Kind regards,
Max

[Unregistered]

I understand you're bronken from inside!

Aren't you that need an MD that detects diamonds ?

Which kind of metal is a diamond ?

But maybe using a CA3140 you'll solve your problems , eh ?

And what if rubbing it with some eye cream and $hit of camel ???

You need a serious psycotherapy!

Kind regards,
Max

Hi max certain south african woo doos practice using these stuff in football fields etc etc, also our max was rubbed with that alien stuff when he was in cloaca....

some in this forum say they detect diamonds with lrl's, people here suceeded, one geologist has a direction finding one and he is a success....

[Max]

Hi max certain south african woo doos practice using these stuff in football fields etc etc, also our max was rubbed with that alien stuff when he was in cloaca....

some in this forum say they detect diamonds with lrl's, people here suceeded, one geologist has a direction finding one and he is a success....

You rub yourself with that eye cream... even in other parts I think.. not just eyes.

That's why you have such "imagination"

Uhm... your diamond adventure will never start... unless you'll use some flower/grass to improve your powers... like popaye the sailor man!

Kind regards,
Max

[Unregistered]

MAX

You rub yourself with that eye cream... even in other parts I think.. not just eyes.

That's why you have such "imagination"

Uhm... your diamond adventure will never start... unless you'll use some flower/grass to improve your powers... like popaye the sailor man!

Kind regards,
Max

Mr Max 555 is not outdated, african and americans use 555 in many projects. ZIf Afircans use 386 based chip u call them outdated project, if one used dual core, u call that country advanced country...most 555, TL071 , LM709 are made in 1980's...u will change ur attitude if u find a devil in a remote outskirts of ur village...then u will think of other issues than ur metal detector variants with different IC's without any increasing depth improvemets....are u still stuck up in that cloaca glued to it....UK has very ancient history...one fellow here by name Great Alex from middle east says his culture is ancient...but its just 1000 years old...his talk is similar to ur talk....

[Rolie]

You rub yourself with that eye cream... even in other parts I think.. not just eyes.

That's why you have such "imagination"

Uhm... your diamond adventure will never start... unless you'll use some flower/grass to improve your powers... like popaye the sailor man!

Kind regards,
Max

sorry for my english, I latin, Max some what keenly involve into this schematics, may be he found a devil in the UK remote villages, I think he not from UK, he may be asian...as one postings say he think using 396 cpu based projects with assembly language are savage and meant for under developed country , dual core base projects with C++ and microsoft are meant for advanced country.....hats of to max