PICKINI - an easy to build PI detector

[F117]

Hi Vic,
the wire I used for this particular coil was just ordinary stranded multicore mounting wire with PVC insulation, something I had laying around:



inner diameter: 7 x 0.193 mm
outer diameter: 1.4 mm

I am not a coil expert and I refer to the loads of information that are available on this excellent forum ( especially the "coils" section).

Regards,
- Bernard

[F117]

Hi Dirk,
I modified your battery connection diagram with 2 diodes 1N4001...1N4007.



When you connect batteries in parallel without diodes, one battery (or in this case 2 batteries in series ) - the one with the highest voltage - will charge the other one and you will have "circular" currents. The 2 diodes prevent the batteries from "seeing" eachother.

Regards,
- Bernard

[DIVER]

Hi Vic,
the wire I used for this particular coil was just ordinary stranded multicore mounting wire with PVC insulation, something I had laying around:

[ATTACH]25586[/ATTACH]

inner diameter: 7 x 0.193 mm
outer diameter: 1.4 mm

I am not a coil expert and I refer to the loads of information that are available on this excellent forum ( especially the "coils" section).

Regards,
- Bernard

Hi Bernard,

Many thanks!

Best regards/ Vic

[Dixix]

Hello Bernard
It is wise to diodes. I've learned something. Thanks for the advice!
All the best
Dirk

[Dixix]

My PICKINI is finished!

Here is my version of Bernhard's PICKINI. The circuit is in a self-made aluminum housing. The batteries are housed together with the circuit in this aluminum housing. (for about 3 hours of searching) For the coil I have old vinyl - LP's used. The linkage is push together. This is a remodeled camera tripod (monopod). The detector thus has very little weight. And fits into a small backpack. I love it!
Once again, thanks to Bernard for the publication of this beautiful project!!
All the best

[satdaveuk]

You done a nice job there
Hope that old record wasnt a beatles or elvis because it would be a crime lol

[F117]

Hi Dirk,
A very nice build
I also sincerely hope that you didn't use any classic albums for the coil... The right one looks a bit like "Rumours" by Fleetwood Mac ? (just joking)

Nice stem construction.
What sort of material is the lower stem - close to the coil - made of ? The last 50 cm or so should be non-metallic.

The battery capacity - 200 mAH - is very low. It surprises me that you even get 3 hours out of these batteries. When you want to stick to this form factor, there are 9V blocks with higher capacity like this one - 500 mAH:
http://www.conrad.be/ce/nl/product/251292/

You could replace 4 of your batteries with only two of these in series.

Have fun and happy hunting,
- Bernard

[F117]

The 9V battery I mentioned here http://www.conrad.be/ce/nl/product/251292/ is in fact a 7.2V LiIon battery in a 9V block housing.
Needs a special charger, not the simple constant current source for NiMH.

[Dixix]

hello
No, do not worry, I have no used precious LP's used. It's "Rumtata" - music. This is something for grandmothers and grandfathers.
For the detector - rods I have used an aluminum photo mono-pod. The lowest segment I have replaced with a plastic rod. In plastic rod I have previously milled groove 2x. (With a Table - Router late). I also cut all the segments. For many working a Dremel (small hand drill) was a great help for me.



Thanks Bernard for the tip to use other batteries. I have the life of the Emmerich - Batery not tested in the field. I have the detector switched on only at home, and after about 2.5 or 3 hours, the batteries ran out.
I think in the field are the batteries do not live as long.
all the best
Dirk

[gavabeach]

Hello again , i'm in proces to finish the Pickini and i want to share my work:



Excuse in advance for my bad English.
The beach is Barcelona-barceloneta at night where some guys search with metal detector.
Well, two questions:

1) it's possible to adjust Pickini for work in 12 v. ?

2) Are there to add some push button in the circuit ?

Best regards to everybody.

[F117]

Hi Gavabeach,
nice pictures, and the Barcelona beach at night also looks nice - not just for metal detecting !

I can see you connected a yellow and black wire between pin 7 and GND. Pin 7 is a digital output that indicates detection or not -- 5V or 0V. You should connect a series resistor of e.g. 1K here and an LED for visual detection indication.

The power supply is stabilized at 12V -- you need at least 14.5 V input voltage from the batteries. So you can not run it directly from 12V batteries.

No push buttons are required.


Best regards,
- Bernard

[gavabeach]

Thanks Bernard for reply.
Between pin 7 and GND i had conected a little buzzer , but seems more discrete one led.
I am working for finished the Pickini and share more photos.
Regards.
Jesus.

[6666]

Hi F117
just wondering what your thoughts are ,

can you see any advantage in adding an extra opamp to your circuit
to give a bit of extra gain,
like they did in BRN PI-1 ??

[F117]

The analog front end is very basic and can definitely be improved. As long as you feed the flyback pulse to the micrrocontroller it should work without changes to the software.

[6666]

Thanks F117
what is the maximum signal voltage that can be sent to the PIC ?