Goldscan lV PCB

[Silver Dollar]

I found this somewhere;

[Dean Sarelius]

Hi Silverdollar,
Inside the rar is the "GOLDSCAN IV.LYT" file but when I open with Proteus I dont see anything except for a rectangle.
If you can send this to me I will get some boards made and send one to you for free if you like, if I have any spares I will give these away also..!
Cheers,
Dean

[Silver Dollar]

Funny I open it with 7.7 and see this;

[greylourie]

Hello all,

Sinclairuser is right, there is no decent board layout available. The board that Jose' used, is (I think) the smd one, with schematic produced in ISIS. And he had found it was difficult to get working, requiring some fiddling and hacking. The one that Silver Dollar posted is a Turkish clone. Have not seen anyone build that one.

Alexismex posted the first back-engineered schematic. He also posted some nice photos of the original board, that could conceivably be used as reference for a new board. Sadly I have zero experience in using schematic/layout software (maybe the time is nigh).

Ivconic has posted up a schematic (http://www.geotech1.com/forums/showt...691#post181691) in ExpressSCH format, BUT, at the time had not gone over it to make the various corrections and modifications that were suggested in various posts scattered over a few threads.

Possibly Ivconic had some spare time over the winter, to update his work... and will reply here ?

[Dean Sarelius]

Hi Silverdollar,
When I open with 7.8, I see the following..

[sinclairuser]

the main problem here is no one is prepared to reverse engineer eric's designs in a pure manner(except george), they allways tinker and change, the subtle ways eric does things will be lost that way.
the only way to do this is like how george has done the mini pulse, reproduce it completely from the board up, then just modernise the bits that are hard to find, or not used.
you must resist the temptation to change components willy nilly, if you do that with one of eric's designs it will wend up a mess.
and it will not work as intended, he comes here, ask him to let us have the proper design, or at least over see the attempt, why bother unpicking this if we can have it pure.

[bernte_one]

forget goldscan
the performance isn´t that what most suppose

there are some analog and µC units which perform better
what some forget is that most thinks that have gold in its name are not every time deep seeking machines
they are often better for small pieces

[greylourie]

Hi sinclairuser,

I hear what you are saying. It would be nice to have a vanilla version for people to work on. But we have to be sure if we want a replica, or as many builders have asked for here in the past - a ground balancing P.I ? Because I think that the Goldscan would make an excellent basis for modernisation, simplification and improvement. From a purists perspective, I would love to say I have built a replica 100% true to original. But from a Geotech perspective, perhaps a project that would be easier to build and debug would be the way to go.

On the few threads covering the Goldscan, theres a large number of posts by Reg, Jose' and others that suggest improvements that would make it easier to build, and set-up. The four part schematic by Alexismex reportedly contains one error and one omission. All the other schematics have the added 47K resistors that modify it from non-motion to motion type behaviour and remove the drift that all builders experienced. The other issue highlighted is the noise that comes from the power supply,with posts offering solutions to that.

Reg has also made numerous posts covering the use of low/zero-offset opamps that make it possible to remove of some of the tricky offset trimmers. This would remove another potential stumbling block for builders. And improve sensitivity.

In Ferric Toes thread (http://www.geotech1.com/forums/showt...ircuits-for-PI), he has posted an example of the Track/Hold Differential Integrator that is common to many of his designs. But in that thread he says he does not use it anymore. Perhaps use the simpler integrator topology of say....the Hammerhead ? And follow it with a 2 Pole filter similar to the one KingJL built into his HH. In the Ferric Toe thread I referenced above, the attachment has a comment that CMOS analog gates are better than the J113's. So there is a tip from the man himself on a potential way for incremental improvement in performance.

The work done by Jose' has offered a modification to the schematic that gives a working High/Low conductor setup, and the working example is nicely shown in his youtube video.

What do people want ? A true-to-form replica ? Or a Geotech project that contains elements (TX, Receive, Audio & Power) that make up a good project for construction.

If the right people with electronics and layout expertise had input, this could end up being a great machine to build - with the potential for performance and features similar to commercial detectors that were spawned from the original Goldscan.

[greylourie]

forget goldscan
the performance isn´t that what most suppose

there are some analog and µC units which perform better
what some forget is that most thinks that have gold in its name are not every time deep seeking machines
they are often better for small pieces

Hi bernte_one

The micro-controlled projects are nice. Micro controllers can help eliminate many components and improve performance. But there is nothing wrong with analogue models either.

The name is not important. The fact remains that this was designed by one person with a prolific record for designing some of the most popular analogue P.I.metal detectors ever commercially sold.The Goldscan was introduced as a commercial ground-balancing metal detector. And although the design is well over twenty years old now, it is the grand father and precursor to the Whites TDI.

This detector has a large range of adjustment controls, and requires a steep learning curve (even for some experienced detector operators). With the right input from the experts here on Geotech, it could be simplified and improved. With changes to pulse rate and a rearranged Tx and power supply (amongst other things), there is no reason this could not be similar in performance to commercial models. Or maybe even better......

I think that an improved model would make a great Geotech project, and could be swept along any beach or at any field meet by the owner-constructor with pride and confidence.

[bernte_one]

i think goldscan i really complicate
if you search a good analog modell with great documetation
i think the hammerhead, crossbow classic pi or the mirage pi are much better

i have made goldscan partially (self etched smd board, some components..) but see yourself try it

[mschmahl]

I have an original Goldscan 4. Only Coil and Battery is not original. So i can messure some part´s and make photo´s if something is necessary. The depht in normal mode without GB and Disc is very good. But with GB and Disc it lost a good part. But this could be because the homebuilt coil and wrong adjustments of the internal controls.

[Qiaozhi]

The depht in normal mode without GB and Disc is very good. But with GB and Disc it lost a good part. But this could be because the homebuilt coil and wrong adjustments of the internal controls.

The loss of depth with GB switched on is due to the subtractive method that is being used. However, with GB turned off, it can be impossible to use the detector in some highly mineralized areas. So lack of depth is the price you pay for having ground balance. The idea here is that it's better to be able to detect shallow targets than none at all.

The DISC feature is similar to the TDI, in that it discriminates using target conductivity. This is not ferrous / non-ferrous discrimination like a VLF.

[Toros]

Hi Silverdollar,
When I open with 7.8, I see the following..

.gif is not Proteus PCB file. Open it with Windows paint program.

[satdaveuk]

I for personally welcome modifications and improvements to old designs but lets get the originals where possible fully functional as per manufactures specification first , Not just a quick fix due to lack of understanding and knowledge of how the design suppose to perform or lack of skills regarding construction.
Seen it here a few times where by components have been deleted in later designs with total disregard to there original purpose, which in my opinion is poor and not a professional example for the young up and coming engineers on here.

Another thing while on the subject which should have been implemented along time ago is, If a original design is dramatically altered from the original manufactures specification its should be named as such instead of confusing everyone with different versions, A good example of doing things correctly was the Tesoro Golden Sabre which Ivonics modified and refined and named it Tesoro Golden Sabre Light (TGSL) which I thought was fitting due to it been a lighter design because he had done away with Notch facility together with some extra refinements without destroying the original manufactures design.
A bad example which started off so well was the Famous Barracuda by Anchor Electronics a non Motion PI far ahead of its time, which if replicated identically to the original design is outstanding. But to this day for reasons I cannot understand and never been explained why the Silverdog kit was modified in such a way its working characteristics replicated the same as the Whites Surf a motion PI which is fine, but should never have been called Barracuda- anything period, because it was altered to something other than Barracuda.

Going back to the Gold Scan, Would be great if it could be sorted out to a practical working design, Been following it on/off for the last couple of years, got all the earlier diagrams etc which willing to share if they are of any help but proberly not.

Regards

[Dean Sarelius]

Hi All,

I managed to get the Goldscan PCB to load up in 7.8 it was a path issue when I was opening the file it kept defaulting to "untitled.lyt" so was struggling to open the file..!
So before I get some PCB's made can someone verify that this is the most up to date version please..?