Mirage PI Project, anyone interested?

[Hammerhead]

Salam Hammerhead, great that you are still around! How it is going with your arduino board detector?

I have an interesting youtube video for you:

Sunken Ancient City of Heracleion
https://www.youtube.com/watch?v=xFz-uWIEKiM

Because many old treasures of Alexandria are meanwhile 5 kilometers out on
the sea and under water - because of earthquakes and ancient Nile-floods.

Hello my friend diving in this places is permitted only for the owners of yellow hair and blue eyes we see us as thieves look into the background of the picture do you see this island one of my friends divers found a gold coin of the Greco and I know every centimeter in this area, but engineers Ghabia downloaded to fill the area were destroyed. this archaeological area beautiful

[Hammerhead]

Salam Hammerhead, great that you are still around! How it is going with your arduino board detector?

I have an interesting youtube video for you:

Sunken Ancient City of Heracleion
https://www.youtube.com/watch?v=xFz-uWIEKiM

Because many old treasures of Alexandria are meanwhile 5 kilometers out on
the sea and under water - because of earthquakes and ancient Nile-floods.

[Hammerhead]

All this havoc and destruction because of this failed project dreaded

[Funfinder]

First my condolences to the interesting and beautiful city of Alexandria!
It's not good for tourism and the people if everything there is in fear of terror.

And next sorry to you, Hammerhead, I did not saw your new interesting postings earlier.

Your pictures are really interesting! This is (or was) still very close to the usual beach.
But perhaps you also can go a little bit outside of Alexandra close where the Nile
once was - near the fields of little villages - and you try your luck there!
At least you can find very old carved stones or sculptures from Roman times.

Too bad that the treasure-site directly nearby is totally flooded!

At least it will become easier for you to find older stuff at the beach if no
longer many tourists pollute everything there with junk!
I hope you can dig 1 meter deep holes at the beach without getting any problems!

[Chiv]

Kit turned up today, thanks Sven1, well packaged even customs had opened it for a look, must of been a strange picture on there x-ray machine.

[qute1]

Both boards and kits arrived this morning (after customs had a squizz and charged me a tenner for the privilege and it only took them a week) dunno what they think baddies use md kits for......

[homefire]

??? What did they base the Customs Duty on ?

[Polymer]

[QUOTE=geoscash1;224396]I have used a couple different cases for the mirage ( see pics below).. the best fit so far has been the one below in the ebay link or "mirage 1" build and it is relatively cheap compared to other cases. its a nice case for the price too. Just spend some time on your layout before drilling and you'll be fine.

mirage 1 - inside

mirage 1 - front panel

mirage 1 - rear panel


Mirage 2 - front panel

Mirage 2 - completed (difficult case, solid one piece, only removable ends)


Nice build! What parameter do you use the 10-turn pot for? (Rdamp, Delay etc.)

Thanks ... Polymer

[qute1]

Homefire : No idea but got a slip through the letter box on Friday saying held at customs with £11.75 to pay (you can pay it on-line) and then RM deliver it 4 days later.
I have been soldering all afternoon never seen so many jumpers on a kit before, about 30 little bits of wire to bend and fit on each board (single sided pcb's) but now have the ic sockets and jumpers done on both boards so can start on the psu bits and the rest tomorrow.
It SOOO hot here i am cream crackered after just 4 hours even harder as trying not to drip sweat on the pcbs.

[hendra]

[QUOTE=Polymer;247978]

I have used a couple different cases for the mirage ( see pics below).. the best fit so far has been the one below in the ebay link or "mirage 1" build and it is relatively cheap compared to other cases. its a nice case for the price too. Just spend some time on your layout before drilling and you'll be fine.

mirage 1 - inside
[ATTACH]38047[/ATTACH]
mirage 1 - front panel
[ATTACH]38048[/ATTACH]
mirage 1 - rear panel
[ATTACH]38049[/ATTACH]

Mirage 2 - front panel
[ATTACH]38050[/ATTACH]
Mirage 2 - completed (difficult case, solid one piece, only removable ends)
[ATTACH]38051[/ATTACH]

Nice build! What parameter do you use the 10-turn pot for? (Rdamp, Delay etc.)

Thanks ... Polymer

hello sir, do you have schematic Mirage PI 2 and the layout pcb and component ? i want to try make Mirage PI
regard

[SVEN1]

I can sell you the current 2018 version PCB along with the schematics. I do not offer the lay files. Nor do I offer the schematics free, it would be unfair to anyone who has invested $$$ to buy a PCB etc.

Since I have had some bad luck sending items to Indonesia, there will be no guarantee of swift delivery or actual delivery if you order a PCB. And I will no longer send a free replacement.

The only way I will ship a PCB and Parts Kit if it is shipped insured and tracked. But, shipping is very expensive. That way if the parcel gets lost I can file an insurance claim to recover all costs.

I did respond to your message to me on ebay, to search Geotech for a PI to build and a way to contact me direct. If your still interested send me an email thru my website link, click on the mailbox at https://www.treasurelinx.com/zm.html

[homefire]

Roger on the HOT. Just showing signs of cooling down here near the Dotted Line. I have two of these PCB in my TO DO SOME DAY BOX ! Have most parts on hand . Couldn't pass up a good deal . LOL

[Elliot]

Hi Sven,
I have completed building the circuit board, and all is working well.
A couple of questions:
- Does the pcb need to enclosed in a metal (i.e. shielded) box, or can I install it in a plastic box with no worries?
- I have found a very low capacitance cable to go between the search head and the control box (7pf per foot between adjacent wire conductors - excluding the shield). It also has a woven shield that I can use. Do I need to use the shield, or can I simply use the twin core wires (twisted)?
- If I need to use the shield, should it be connected within the search coil to the coil shield/virtual earth star point, or could/should it be connected to the virtual earth (+ve in this case) at the pcb?
- The speaker volume is very low with an 8 ohm speaker - even if the 10 ohm series resistor is bypassed. What workaround do you recommend for this?
- I have built what I think may be a very fast coil using a planar spiral design (2.2 layers), with foam padded filler used before adding copper foil shielding (measuring the self resonating frequency seems to be a vague and fraught process). I have researched everywhere about how to optimise the damping resistor. Some articles say that a lower resistance can overdamp the return signal, while others say reduce it as far as you reasonably can, I assume that a lower resistance will deliver a faster voltage drop, but how do I optimise? Do I simply keep reducing it until I start seeing some ringing on the cro, and then back off of a bit?
- I also want to add the auto-track freeze feature as per the Hammerhead design. Do I simply cut the track and put a switch between pin 5 of TL072 and the 220k Sat Adj resistor?

Thanks in advance!
Elliot

[Elliot]

Hi Sven,
I have completed building the circuit board, and all is working well.
A couple of questions:
- Does the pcb need to enclosed in a metal (i.e. shielded) box, or can I install it in a plastic box with no worries?
- I have found a very low capacitance cable to go between the search head and the control box (7pf per foot between adjacent wire conductors - excluding the shield). It also has a woven shield that I can use. Do I need to use the shield, or can I simply use the twin core wires (twisted)?
- If I need to use the shield, should it be connected within the search coil to the coil shield/virtual earth star point, or could/should it be connected to the virtual earth (+ve in this case) at the pcb?
- The speaker volume is very low with an 8 ohm speaker - even if the 10 ohm series resistor is bypassed. What workaround do you recommend for this?
- I have built what I think may be a very fast coil using a planar spiral design (2.2 layers), with foam padded filler used before adding copper foil shielding (measuring the self resonating frequency seems to be a vague and fraught process). I have researched everywhere about how to optimise the damping resistor. Some articles say that a lower resistance can overdamp the return signal, while others say reduce it as far as you reasonably can, I assume that a lower resistance will deliver a faster voltage drop, but how do I optimise? Do I simply keep reducing it until I start seeing some ringing on the cro, and then back off of a bit?
- I also want to add the auto-track freeze feature as per the Hammerhead design. Do I simply cut the track and put a switch between pin 5 of TL072 and the 220k Sat Adj resistor?

Thanks in advance!
Elliot

[waltr]

I have researched everywhere about how to optimise the damping resistor. Some articles say that a lower resistance can overdamp the return signal, while others say reduce it as far as you reasonably can, I assume that a lower resistance will deliver a faster voltage drop, but how do I optimise? Do I simply keep reducing it until I start seeing some ringing on the cro, and then back off of a bit?

Look at Pre-amp output on scope. Without damping R you will see ringing. Decrease value of damping R until ringing is gone and a smooth exponential decay curve is seen.

I prefer a shielded (metal) enclosure but seem many PI detectors are built into plastic boxes and work fine.

If you have shielded the coil then this shield needs to be connected to the circuit "ground" (virtual earth). Several ways to do this- either on the cable shield or on the "Ground" coil connection.
On my modified HH I do not shield the coil or run a shielded cable. Works fine with CAT-5 cable but YMMV.

Which cable and shield connection scheme works best may need to be determined experimentally.