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

[nick holas]

thanks for your help
lm318
1->9.5
2->6.8
3->6.8
4->0 ???
5->4.8???
6->7.4???
7->1.4

pic
1->4.95
2->2.4
3->260mv????
4->5
5->4.7
6->0.9
7->0
8->5 ?????
9->30mv????
10->2.4
11->0-5v
12->2.6
13->1.3
14->0
here s my value with 3x18650 pack at 11.25v
thank you

[Teleno]

Apparently, nobody has made it working so far.

In the mean time, feast your eyes on some typical finds from the seaside dunes.
At first, I thought I had found a cannonball, but after digging 1m deep, it turned out to be a petanque ball.
Next: toy car, pull tab, aluminum French WW2 coin, tent peg,... lots of pieces of barbed wire (WW2 remains).





Have fun,
- Bernard

Obviously yu're in the Netherlands. So am I (Den Haag). My "tresure" finds look very much like that. Tent pegs might be worth something.

Perhaps we could cooperate in some detector designs. I got lots of ideas and little time, could use some help.

[F117]

@Nick Holas:
pin 3 of the PIC is the sensitivity input - you can change it with your potmeter between 0-5V

It's obvious that there is something wrong with the automatic DC adjustment of the opamp.
When you switch on the detector and measure at pin3 of the opamp, you should see it change every second. Also pin 13 of the PIC = analog output will change gradually.
When it does not detect a flyback pulse during the adjustment, it will continue until it reaches the positive rail or 0V and then give the coil error sound.

So, check the circuit around Q3 first. If the DC voltage changes gradually every second, that is fine.

Next is the coil connection: do you get a flyback pulse every 2 ms at the coil side ?

- Bernard

[nick holas]

bernard could you tell me if i m right?
about your pickini v4 coil ,its the same of old pickini versions??
i made one 230mm 27 turn 235µh 1.2ohms is that good??
im trying to take mesurements about what you say before!!!
all voltages seemed to be ok only pin 4 of lm318 is 0v instead of 8v
pin 8 of pic must be 0v i have moving voltage 2.88-5v every 2s then fix to 5v,pin 9 must be 3.7 i have -100mv!!!!
by the hell!!!!!!
many thanks

[F117]

pin 8 of pic must be 0v i have moving voltage 2.88-5v every 2s then fix to 5v,pin 9 must be 3.7 i have -100mv!!!!

When you look at the schematic: pin 8 and pin 9 are connected. they should both be around 3.7 V.
My mistake, I measured it again to verify and modified the electronics web page accordingly.

Please check your layout -- I am assuming you are using your version of the PCB layout instead of the original one I supplied ?

The coil can be the same as all other pickini versions. The specs you quote should be OK.

Best regards,
- Bernard

[F117]

Hi Nick ,

When I look at your PCB layout:

can you check the connection between pin 8 and pin 9 of the PIC?
They should be shorted.
See attached image:



Hope this helps,
- Bernard

[F117]

@ Teleno:

Obviously yu're in the Netherlands. So am I

I live in Belgium, but I am a major fan of Zeeland - up to 50 km south of Rotterdam ( HellevoetSluis).
I love the Dutch coast - as it is still natural compared to the Belgian coast.
During many holidays at the Zeeland coast I have gathered a complete orange outfit that would turn any Dutch soccer fan jealous .

I would love to spend more time on developing and exploring detector techniques, but unfortunately ( for this anyway), I have a family and a full time job.
That is why it took me over a year to develop and ( most of the time ) field test this one, before releasing it here.

Custom electronics and firmware are my hobbies (next to a 1000 other things if only I had more time...).
I am always open for new ideas - especially when it comes to metal detecting.

Beste groeten, - Best regards,
- Bernard

[nick holas]

houra!!!!!!!! it is alive!!!!!!!!
it was just one connection between pic pin 8 and 9
whouaiiiiii super !!!!
ready for tomorow beach hunting but this time in wet sand (euro ace can t!!!)
thanks a super lot!!!
just have to fine finish my coil put all that on my shaft and GO! GO! GO!
treasure and gold beware i m coming !!!
send you a foto of finish product
thanks again

[Arionas]

When you look at the schematic: pin 8 and pin 9 are connected. they should both be around 3.7 V.
My mistake, I measured it again to verify and modified the electronics web page accordingly.

Please check your layout -- I am assuming you are using your version of the PCB layout instead of the original one I supplied ?

The coil can be the same as all other pickini versions. The specs you quote should be OK.

Best regards,
- Bernard

This and this and this and this ok .......Mr F117(Thanxs)

[F117]

@ Nick Holas: glad to hear it works now. Happy hunting !
@ Arionas: the layout you are showing is OK.
The only thing that I see wrong is the type of PIC controller: it is not 12F1824 but 16F1824 on the PCB mask. A minor detail, but people might purchase the wrong part.

Have fun,
- Bernard

[eclipse]

Perhaps instead of C9 (10uF) we can use 220nF-2.2uF polypropylene type capacitor (for lower ESR, lower noise)?

[Arionas]

@ Nick Holas: glad to hear it works now. Happy hunting !
@ Arionas: the layout you are showing is OK.
The only thing that I see wrong is the type of PIC controller: it is not 12F1824 but 16F1824 on the PCB mask. A minor detail, but people might purchase the wrong part.

Have fun,
- Bernard

Good Morning Mr F117
THE MISTAKE WAS MY OWN ...... WHEN WE BUILD SOMETHING ALWAYS follows the pattern

[F117]

@Arionas: PCB mask is OK now. Nice work !

[F117]

@Eclipse

Perhaps instead of C9 (10uF) we can use 220nF-2.2uF polypropylene type capacitor (for lower ESR, lower noise)?

I am not an analog electronics specialist. The only thing I have observed on the scope is that with a pulse duration of 100 microseconds and a pulse cycle of 2 ms, the coupling capacitor has to be large enough to maintain the DC level over the entire period.
When the capacitor value is decreased, it starts acting as a differentiator, resulting in a negative going pulse = flyback pulse, then returning to DC level and gradually dropping again over the rest of the 2 ms.
I am sure that this effect can be overcome in software by just enabling the pulse comparator during the flyback pulse and discarding any level drop later on in the cycle.
This could be an improvement, but so far all the tests I have done were with this 10 microfarad value.

To elaborate even further on this: I am sure that the entire analog front end can be optimized in combination with the PICs capabilities of automatically calibrating/ adjusting some DC levels.
As I mentioned before: I am not an analog electronics guru. But I would like to team up with one to optimize software and hardware capabilities to come to an even better and maybe final solution for a temporal sampling detector ( Pickini V5 ?). Any ideas/inputs in this direction are more than welcome. Probably starting with an entire DC coupled simple front end and a negative supply voltage for the opamp ( ? ) . Or even considering the usage of a PIC with a built-in opamp - (bandwidth ??? ) ....

Best regards,
- Bernard

[ripsdevala]

houra!!!!!!!! it is alive!!!!!!!!
it was just one connection between pic pin 8 and 9
whouaiiiiii super !!!!
ready for tomorow beach hunting but this time in wet sand (euro ace can t!!!)
thanks a super lot!!!
just have to fine finish my coil put all that on my shaft and GO! GO! GO!
treasure and gold beware i m coming !!!
send you a foto of finish product
thanks again

Congrats!
If you have a video test that would be great, its been a week but my chip is still stuck on china