PICKINI V3 - an easy to build PI detector

[bernte_one]

will update it in exact
2h 30m (after work) happy !!!

Big THX

[bernte_one]

ok
just tested it
got a bronze buckle at 40cm in air with 45cm dia coil around 600µH unshielded monoloop yv5 wire 0,5mm dia

pin3 of µC set on 5,2V DC

sens seems better external with audio amp

thanks Bernard

[bernte_one]

next test results
with an older spiral coil 250mm aD 10cm iD from surf pi / baracuda projects
i can detectd a 0,39gram gold nugget at 7cm in air

[edu38]

Dear sirs:

can anyone upload a mirorred file for heat transfer board method? Thx in advance ...Eduardo from buenos aires.

[6666]

next test results
with an older spiral coil 250mm aD 10cm iD from surf pi / baracuda projects
i can detectd a 0,39gram gold nugget at 7cm in air

Bernard, I have not made this MD yet, but for a test could you please try something like a 1978 1 deutsche mark coin ?
as I have this coin in my collection for testing.
Thank you.

http://img.ma-shops.com/kohlross/pic...lus2-j-385.jpg

[F117]

@edu38:

I added a monochrome PDF of the COMPONENT side of the board here:

http://users.telenet.be/willaert/MD/...ectronics.html

I am not sure if this is what you want for heat transfer ... ?

The Cu side of the board layout is also on the page in PNG

[F117]

@Bernte_one:
Thank You for sharing your test results !

@6666:

I am sorry, but I don't have a Deutsch Mark from 1978 - only old Belgian Franks and Euro coins.
Also, test results are largely depending on the coil used. The electronics are merely amplifying the flyback pulse and evaluating the pulse width.
For small coins eg, I get better results with a 20 cm coil than a 28 cm coil.

- Bernard

[6666]

Sorry F117, I meant bernte_one Bernard.

[Beenthereuk]

I've decided to build one of these too and have the PCB all working as it should, 5.3 V on pin 3 of the PIC.

After a few seconds (DC voltage stabilising, I'm guessing), during which time it clicks softly every second, current consumption increases to 160mA (from around 16mA on start-up) and it starts to bleep rapidly as if detecting metal close by, when there is none.

I have not foil-wrapped the coil yet (306 uH, 26 cm diameter, ~20 turns), would that cause the constant bleeping?

I've also dropped the voltage gradually down to 5V and it loses the return pulse at around 8V (audible warning) but I do not get a low voltage warning.

[bernte_one]

hello been

can you palease make some pictures of your setup
especially the audio part

[Beenthereuk]

Will do so tomorrow when I get my camera back. For audio out, for testing, I've simply wired a 64 ohm speaker between X3-3 and GND - its low but good enough for testing.

I guess its best if I do a video of it; I'll upload soon.

[Beenthereuk]

Not the best quality (off my phone) but it can be seen and heard operating:





http://tinypic.com/r/16j0h8p/8

[F117]

After a few seconds (DC voltage stabilising, I'm guessing), during which time it clicks softly every second, current consumption increases to 160mA (from around 16mA on start-up) and it starts to bleep rapidly as if detecting metal close by, when there is none.

In Your film, supply voltage=12V and current = 120mA seems normal.
When you want a power supply range of eg 11-14V, adjust the 5V at pin 3 of the microcontroller with a power supply of 13.5V. This way, it will remain stable when the voltage drops.
When you do the opposite: adjust the 5V at 11V, it will become unstable when you crank up the voltage to 14V.
The voltage divider at the virtual ground opamp input takes some time to stabilize when you change the supply voltage quickly.
So: adjust the 5V at pin 3 with the power supply at 13.5 / 14V.

I have not foil-wrapped the coil yet (306 uH, 26 cm diameter, ~20 turns), would that cause the constant bleeping?

Coil looks OK. For testing it doesn't matter if the coil is shielded or not. You will experience false signals when touching the ground with an unshielded coil in the field / on the beach.

I've also dropped the voltage gradually down to 5V and it loses the return pulse at around 8V (audible warning) but I do not get a low voltage warning.

The low voltage audio detection has a delay of about 25s and will be repeated once every 25s. This allows you to keep searching even when the battery goes low.

PS: what is that red thing on top of the large tank capacitor (2200 microFarad) ?

PS2: if that thing you're waving over the coil is a soldering iron cleaning "spunge" - copper filament,... you should be able to detect it at 30-40 cm at least. That is also the first thing I always wave over the coil.

- Bernard

[F117]

For audio out, for testing, I've simply wired a 64 ohm speaker between X3-3 and GND

Should be OK. If output is too low, you can decrease the series resistor value.
With simple / cheap headphones, the audio is excellent.

[sinclairuser]

hi been there uk, your coil connector could cause falses, i used those block connectors on the first pi coil i made, and it detected it, it falsed like hell, when i removed it and soldered the wires it stopped, i dont know if it detects the brass or the steel screw but my first pi saw it.