2nd Chance PI

[dantech]

Follow the picture. I prefer 0,8 mm wire. Then we have 1 ohm and 350uH

I think that 0,6 mm can be also used but resistance will be higher eg. 1,7 ohm, inductance should be circa 380uH. So the coil can be little bit slower (2-3 us)

[ripsdevala]

Coil industance, resistance?
Or just following the pic, 24 (12+12) top bottom, and outer 18 (9+9) top bottom. I have 0.6mm wire

[dantech]

Right, I was looking onto another schematic version

[ripsdevala]

This c9

according to the scheme, c9 should not exist, on the pcb layout its connect to pin5 LT1054.

[dantech]

B1,B2,B3 comes from "buttons". This is keyboard connector.
You have to programm in the external socket or solder additional wires under the PCB

C9/C18 is the pair of 100n / 100uF in the positive power rail of NE5534. I do not remember which one is C9.

At the beginning you have to run the circuit without atmega, MCP3201, LT1054 and NE5534.
Then you have to check power consumption (several miliAmps), +5V, +12V, -12V, Uref =4,6.
Next you can place ICs in the sockets. Should start at once

By the way you cabn use ADS7816 instead of MCP3201 also.

[ripsdevala]

All parts complete, let me know if there any mistake, im not sure about wrong choke placement from post behind.

Any voltage measurement?
What is the value of C9?
Programing directly from B1 B2 and B3?

[ripsdevala]

Yes, i see 9640 have a better result than the others, i will try this 9640 to cuda also.

[kt315]

Is there any subtitute for irf9640, the last part.

substitute is in my BOM file for Barracuda. look it in bara thread.

[ripsdevala]

Is there any subtitute for irf9640, the last part.

[württemberger]

Thanks !

[dantech]

This is in fact common project with AndyF. He was developing project a few years ago. Above v121 (and at the 2nd ChancePI) is developed by me
But we have to keep in mind that AndyF did huge work



"Straight from a head"

S1 - left/signal mask -
S2 - right/signal mask +
S3 - up/volume -
S4 - down/volume+
S5 - OK/filter reset
S6 - Menu/escape

Personally I use keyboard PCB layout (keyboard_pcb.lay6 file)

http://chomikuj.pl/dantech/2nd+ChancePI/PCB/keyboard_pcb,5579348996.lay6

That PCB is fully verified with schematic (keyboard_schematic.jpg)

http://chomikuj.pl/dantech/2nd+ChancePI/Schematics/keyboard_schematic,5579303636.jpg

You have to compare both ones

[württemberger]

Hi Dan,

thanks for your great Projekt.
I have a question about the "Switchboard" (Switch 5). Which Pin´s are connected, if the Button is pressed ?

[dantech]

v017 is released. Cosmetic change

[dantech]

No I did not test Crown Caps. I understand that is the brand of beer unavailable in my country site.

But I have tested 2nd Chance on the beach when there were a lot of caps and if I remember well caps were on 3-4th position on the VDI. There was kind of caps on 1-2nd segment.

Probably those caps were made of thinner plate. Generally there was not any problem with caps distinguishing.

I find that v016 is very stable (original v121 was not) and is one fully compatible with old hardware, so if you state that you have some good results with two stage amplifier and 3dss coil you do not have to affraid that v016 will not work

[baum7154]

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I am trying to clarify for followers of this thread needing a gold detector what it will take to make the '2nd Chance' of this thread into a gold detector as very much effort has been spent in the original 'Chance PI Build' thread to achieve this goal. It would be a shame if others are building this 2nd Chance thinking it will detect small natural gold, as it will not.

Perhaps we need to have two Chance PI versions, one for artifacts and one for gold. I have found though that the improvements and modifications made to detect gold also improve detection of other kinds of targets. If you don't have small natural gold to use as a test target a 6mm square piece of the sidewall of an aluminum soda can is a very good simulator. My Chance PI with v1.2.1 firmware sees this target using a 3DSS racetrack coil at 2.75" with the coil resting 3/4" over soil. The 8" round 3DSS coil sees it at 1" farther than the Racetrack. My original/dedicated Chance Pi coil does not see it at all. If the 6mm square AL target is not detected a 1cm square of the same material is easier to detect.

Best regards,

Dan

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To clarify from my last post:

"I am trying to clarify for followers of this thread needing a gold detector what it will take to make the '2nd Chance' of this thread into a gold detector as very much effort has been spent in the original 'Chance PI Build' thread to achieve this goal. It would be a shame if others are building this 2nd Chance thinking it will detect small natural gold, as it will not. "

HOWEVER...Chance PI will detect small natural gold with the proper coil and damping to allow it to operate in the range of 10us and below. Other modifications such as the 2 stage amplifier will allow the detector to operate with sub 10us sample delays. The firmware modifications that Dantech has made should be very useful in operations below 10us as well. Original Chance firmware did not allow sampling below about 9us but Dantech has changed firmware to allow sampling to begin in the range of 5us (with a very fast coil and critical damping) and this is significant for very small natural gold targets.

I have not yet installed V016 in my Chance PI but I am anxious to get it done as soon as time permits. I will post results of the firmware upgrade here.

Dantech have you tested discrimination on a common bottle cap, otherwise known as a Crown Cap (a rusty one would be the best test)? This target is notorious for discriminating as Gold/Aluminum/Nickle at low signal levels but does discriminate properly as IRON at high signal strengths. I'd like to know how the new firmware handles this target.

Dan