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

[BC547]

@morganton:
1. I have built 2 so far and tested extensively on wet beaches / farmland, ... but I can not compare with highly mineralized soil elsewhere. Nor can I compare with other PI detectors. The other detectors I own are all VLF. I only know from my test experiences that a 25cm PI coil goes Deeper! than my XP GoldMaxxPower.
2. I noticed that already quite a few people have made their own version of the PCB. The most interesting part in a kit woudl of course be a programmed PIC controller. The other parts are all commonly available. AFAIK there is no online service or something that will send you a programmed PIC when you upload a hex file. Another business opportunity

[morganton]

1. For those who have built it, how does the performance compare to the miniplus, baracuda, etc.?

2. Is it anticipated that there will be a silverdog PCB or kit?

[BC547]

too louder ) but for a little HP it s very good!! (other beach hunter can hear that you find something and it make them enraged!!!!!!! lol

Careful ! You will go deaf before you get old

If you want louder sound and an LED:
- make R16 100 ohms and connect the 2 speakers of the headphone in series between this resistor and ground.
- leave R17 = 1K and connect a hi-bright LED between this resistor and ground (kathode to ground, anode to the resistor).

Because of the 1Hz tick (1 s high and 1 s low), on each rising slope, the capacitor C15 will shortly allow current through the LED, so every 2s it will shortly flash.
When something is detected, the frequency quickly changes to 1KHz and the LED will flash at 500 Hz, invisible to the naked eye...

So, there is no magic involved, just plain simple electronics and an alternative use for the headphone connection.
Next to hearing your finds, your fellow detectorists can also admire the light show with each pull tab you unearth.

[nick holas]

hi bernard
hi ripsdevala
hi all
To make it louder i ve connected it directly a the output of the pic in the resistor hole (don t mind stereo!!!) and whitout a potmeter its impossible to put a headset ( too louder ) but for a little HP it s very good!! (other beach hunter can hear that you find something and it make them enraged!!!!!!! lol)

bernard ,didn t know a metal detector can switch on a led like that you ve made COOOOOOL!!

working again to make a good coil enclosure, soon i ll post some photo.

[BC547]

Sound too weak: decrease the value of R16 and / or R17 from 1K to 100 ohm.
If you connect a LED to the audio output, it will briefly flash every 2 s and light up continuously ( 1KHz is no longer visible ) at detection.

[ripsdevala]

To check if your coil is pulsed or not, I once made a simple coil tester from a 5V relay coil and a hi-bright LED. As you can see in the pictures, it also works on a VLF detector (XP GMp):

[ATTACH]37828[/ATTACH]
[ATTACH]37829[/ATTACH]
[ATTACH]37830[/ATTACH]

Looks cool
Dont try to randomly put coil cable at the pcb coil output, i just make a portable stove from pickini today.

The md is working very good on air test bernard sir , all is instant no more pain figuring best ic or coil.
Btw i like to put a signal led to the box, im not sure from where should i connect it, and the sound is to low how to increase it.

Arief

[BC547]

To check if your coil is pulsed or not, I once made a simple coil tester from a 5V relay coil and a hi-bright LED. As you can see in the pictures, it also works on a VLF detector (XP GMp):

[BC547]

@geoscash1 : nice board, but don't forget to short circuit pin 8 and 9 of the PIC !

@ripsdevala: Good to hear that you got it to work
So, because of the different pinout of the BS170, you didn't get a pulse to the gate of the IRF740 and you didn't have a flyback pulse back into the PIC.
After initial calibration, this results in a continuous low tone = COIL ERROR sound. This is just a feature I found helpful as an indicator that something is wrong with the flyback pulse. You would have the same error when the coil is not connected at all.
How can you detect if there is a flyback pulse ? Good question.
Maybe some sort of pickup coil and a speaker that is kept close to the search coil ?
The pulse width is 100 microseconds and the period 2 milliseconds, resulting in 500 Hz, with a duty cycle of 1/20. Not sure if you can pick this up as an audio signal.
I never tried it this way, and there may be other ways to verify it, like touching the coil pin and ground with left and right hand. You should feel someting...

Again, this is why the COIL ERROR sound proves to be helpful. At least it points towards the front end = BS170, IRF740, coil, LM318 -> pin 8,9 of the PIC.

Best regards,
- Bernard

[ripsdevala]

Make attention to BS170 pinout

left is SGD right is DGS

[geoscash1]

Nice & clean board, but i think you need to short pin 8 and 9 pic legs

Hey thank you. Yep, I caught the pin 8 & 9 short so will do it when I solder the socket, thanks for the heads up though, much appreciated.

[ripsdevala]

Change BS170 with another
ITS ALIVE!!

[ripsdevala]

There are a number of points in your PCB layout where the ground plane is almost touching other points:

[ATTACH]37818[/ATTACH]

Do you have a flyback pulse every 2 ms ? Check that the IRF740 is not shorted at the points indicated.

No short at all, here is the hi res pcb back, im messing my pcb with full tin, but not get work either. How to check i have flyback?

Anxious to get workin on this project, still waiting on some parts and my chips but in the mean time got my board done and ready to go. Not to bad for my first try at doing my own board... Great thread and lookin like a great project...

[ATTACH]37820[/ATTACH]
[ATTACH]37821[/ATTACH]
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Sorry, not tryin to hijack the thread, just interested in this project so figured to post in here.

Geo

Nice & clean board, but i think you need to short pin 8 and 9 pic legs

[geoscash1]

My attempt at pickini V4

Anxious to get workin on this project, still waiting on some parts and my chips but in the mean time got my board done and ready to go. Not to bad for my first try at doing my own board... Great thread and lookin like a great project...





Sorry, not tryin to hijack the thread, just interested in this project so figured to post in here.

Geo

[BC547]

There are a number of points in your PCB layout where the ground plane is almost touching other points:



Do you have a flyback pulse every 2 ms ? Check that the IRF740 is not shorted at the points indicated.

[ripsdevala]

Ya arionas thats a joined track, pin 8 and 9, its similar with yours.