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

[Qiaozhi]

Ok, but when I hit the "Insert Image" button, it prompts me for a file on my computer !!!! So what have i done wrong ? I am just doing what I am told ..

Try using Manage Attachments > Add Files > Done

[SaltyDog]

Try using Manage Attachments > Add Files > Done

I only get that option when I go into Adanced editing mode, I have been using "Quick Reply". As far as I am concerned if you are not to use "Quick Reply" then it should be disabled, or the "Insert Image" button removed

If I go into advanced editing, then I get an "Attachments" pull-down. In there I see my two files that I have uploaded with question marks on them .... no idea what that means ... doesn't seem to be a way to delete them, so I can upload fresh ones ..

What is the story??? Why is this so hard ..

[Qiaozhi]

I only get that option when I go into Adanced editing mode, I have been using "Quick Reply". As far as I am concerned if you are not to use "Quick Reply" then it should be disabled, or the "Insert Image" button removed

If I go into advanced editing, then I get an "Attachments" pull-down. In there I see my two files that I have uploaded with question marks on them .... no idea what that means ... doesn't seem to be a way to delete them, so I can upload fresh ones ..

What is the story??? Why is this so hard ..

OK ... let's try attaching an image using Quick Reply:


Hmmm ... seems to work just fine.

[SaltyDog]

OK ... let's try attaching an image using Quick Reply:
[ATTACH]49658[/ATTACH]

Hmmm ... seems to work just fine.

Ok, I am using a Linux machine and the Pale Moon browser(Firefox compatible), maybe something to do with that combo? However, I am part of numerous forums, and never had an issue with any of them ... go figure ..

[SaltyDog]

Hi Bernard,

Can the pic be programmed in situ? If so, please provide a diagram..

Cheers

[F117]

Look for "ICSP" = in circuit serial programming:
https://www.geotech1.com/forums/showthread.php?23400-PICKINI-V4-an-easy-to-build-self-adjusting-PI-detector&p=236925#post236925
https://www.geotech1.com/forums/show...185#post245185
https://www.geotech1.com/forums/show...429#post245429

On the PCB in the semi-kit, the connections for ICSP are not foreseen. You will need to hook up wires to an external connector that matches eg the Pickit3 programmer yourself.

[waltr]

On the PCB in the semi-kit, the connections for ICSP are not foreseen. You will need to hook up wires to an external connector that matches eg the Pickit3 programmer yourself.

Another PCB design that did not put the ICSP header on the board!

[SaltyDog]

Another PCB design that did not put the ICSP header on the board!

Yes, I feel that is a serious omission, maybe the next version?

[Goaty]

I have just finished preliminary testing of a waterproof detector housing using a standard Pickini board and all seems to be working well.





One question I have is in regard to the auto-tune function – Is it best to auto-tune with the coil in air or under water where it will be used?


Here are some pictures of my latest effort -






The Pickini seems ideal for underwater use as the sensitivity can be an internal pre-set pot and the only controls through the housing are the on/off switch and pinpoint switch. Switches are easier to waterproof using the rubber boots readily available online, provided a couple of steps are taken to make them more effectively sealed. These include locking in the threaded metal ring with CA glue and some extra sealing with silicone or urethane sealant.


Once I have had a chance to do more testing I will provide more info if anyone is interested. Hopefully no more leaks with this housing!

[6666]

Looks good

[F117]

One question I have is in regard to the auto-tune function – Is it best to auto-tune with the coil in air or under water where it will be used?

The theoretical answer is: switch it on submerged and let it go through calibration while in the water.
The pragmatic answer is: it doesn't matter whether the coil is in the water or not, as long as there is no metal near the coil during the initial calibration.

Nice build

[F117]

Another PCB design that did not put the ICSP header on the board!

At the start of this project, over 3 years ago, it was not foreseen on the PCB.
I always plug the PIC in a socket on the board and get it out and back in again to reprogram.
If you have a connector on the PCB, it would be even more useful to provide a connector on the housing in order to reprogram it without having to open anything.
Or better yet: bluetooth. A serial connection that reprograms the flash/EEPROM.



@Goaty

Some minor remarks to your nice build:
I would have placed the coil connector at the bottom of the housing.
Also, the stem looks rather long to search in water: resistance / drag...
The coil looks quite "hydrodynamic" though !

[SaltyDog]

Hi Bernard,

Back to discrimination ... I have managed a coil/front end to have a discharge curve of <2uS .. this makes the coil extremely sensitive to small gold (my aim).
(For example .. my ring is detectable 300mm away )

I think that with judicious use of the slice level, you can discriminate even with just the one comparator, I intend to change the code to give a different tone when the current period is < than the average (non-ferrous)
compared with current period > average (ferrous). (as you currently have it)

This can only be done with a fast coil as I have just built .. and operating in the correct part of the discharge curve (i.e slice level)

When my semi-kit arrives from you , I will test my theory out .. here's hoping it arrives soon ..

I have attached the curves again .... think of the slice level being around 0.4v on the vertical axis.

[Hammerhead]

[Goaty]

Thanks Bernard and 6666 on your kind words on my detector.


@F117

“Some minor remarks to your nice build:
I would have placed the coil connector at the bottom of the housing.
Also, the stem looks rather long to search in water: resistance / drag...
The coil looks quite "hydrodynamic" though ! “


I appreciate you constructive criticisms and should perhaps reply with my reasons behind the design -
Up to this build I have experiment with several different styles of underwater housing but all had design faults which ultimately caused leakage and damage to electronics and batteries. These previous housings also had problems in accessing the wiring and internal components to make repairs and alterations. Most were made of PVC plumbing and pipe fittings which has the advantage of being readily available and the ability to make strong waterproof joins using PVC plumbing adhesives and , importantly, the priming fluid which greatly improves the effectiveness of the adhesive. The PVC also has the advantage that it can be bent and otherwise re-shaped using heat to make coil housings, sheets and handles. Its two main disadvantages seem to be lack of transparency to spot water leaks and poor machining properties to get a smooth finish for water-tight seals.
Since my earlier failures I have been constantly on the lookout for items which could be pressed into service, especially for effective seals. When I saw my neighbour replacing the canisters for his under-sink water filtration system I asked him for the old ones so I could study their sealing methods.






These canisters were a bit too large to be used as-is for a detector housing but employed very robust and effective ‘o’ring seals on a screw cap with strong, coarse threads.
Before long I came up with a design which might satisfy my requirements.
Fortunately a friend had a metal lathe which was pressed into service to remove the unwanted parts of the canister and , whilst keeping the sealed, threaded cap section, fit clear 5mm acrylic end windows.






Finding suitable adhesives required quite a bit of Internet research as the canisters appeared to be made of high density polypropylene which is notoriously difficult to glue but it did machine beautifully on the lathe.
So, finally, in answer to your comments, the coil connector is at the top so all of the ‘works’ can be removed complete with no wires and cables to twist up when un-screwing the cap. This also makes for easy battery replacement as these are attached in a holder underneath the aluminium chassis/shield, along with a couple of packs of desiccant. The shaft was my standard PVC plumbing design which is readily collapsible to the required length for wading or snorkelling. It can easily cut down later if it proves cumbersome. I’m anticipating that a friend who has scuba gear will test it at greater depth once he gets his gear organised. The housing is only clipped to the shaft and can easily be fitted upside-down so the cable comes from the other end and the internal led indicator can be viewed through the acrylic window. I guess the housing could also be belt mounted to make the coil easier to swing.
As it is, the whole detector is almost neutrally buoyant with the coil end tending to sink. The whole thing could be made negatively buoyant by dropping a small amount of lead into the angled handle and retaining it with a rubber bicycle hand grip (yet to be fitted)


BTW, thanks also for the tuning info.