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

[ripsdevala]

Make attention to BS170 pinout

left is SGD right is DGS

[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

[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):

[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]

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.

[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]

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.

[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]

@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]

@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

Thanks for that reply. I like your idea. I'll have to see if I can remember how to etch boards. I'm getting lazy in my old age and like to build kits, I have the PIC programmer so that part wouldn't be a problem.

[Qiaozhi]

Thanks for that reply. I like your idea. I'll have to see if I can remember how to etch boards. I'm getting lazy in my old age and like to build kits, I have the PIC programmer so that part wouldn't be a problem.

You could always use stripboard as an alternative. I can highly recommend this excellent freeware tool for stripboard layouts ->
https://code.google.com/archive/p/diy-layout-creator/
Go to the site and click on downloads. The program runs on any platform that supports Java.

[ripsdevala]

Good evening,
Yesterday the md is have no broblem at all but now it make sound like this when start.
Sound: start-increase sens-off
https://www.dropbox.com/s/bowkoh7y1s...piki.mp3?raw=1
Its a 330uh 1.4R coil shielded, with 430 1.8R shielded coil is stable but the deep is decreasing, any clue would be apreciate.

[BC547]

@ripsdevala
When you test the detector inside the house, it will pick up a lot of noise.
When you switch it on and the calibration cycle is done with noise present, it won't function properly: you will get false signals.

I have the same result when I switch it on for testing on the bench in the garage, where the wifi access point is located + other sources of EMI.
Increasing the sensitivity in this case will only make the erroneous signals worse.

Before switching the detector on:

1/ go to the place where you want to search ( this is usually outside the house ... )
2/ hold the coil in the air, away from any metal
3/ switch on the detector
4/ wait until you get one or two solid beeps and then the idle tick - takes about 20s
5/ you're all set: start searching


Before starting a search: check your battery voltage ( but that should be standard procedure for every hunt )

[morganton]

You could always use stripboard as an alternative. I can highly recommend this excellent freeware tool for stripboard layouts ->
https://code.google.com/archive/p/diy-layout-creator/
Go to the site and click on downloads. The program runs on any platform that supports Java.

Thanks, I'll check that out. I also found this tutorial for etching that uses 60% vinegar and 40% hydrogen peroxide with kosher salt instead of muriatic acid.
https://lowpowerlab.com/2012/12/15/c...-with-vinegar/

[ripsdevala]

@F117
I forgot that part, will try again later, thank you

Thanks, I'll check that out. I also found this tutorial for etching that uses 60% vinegar and 40% hydrogen peroxide with kosher salt instead of muriatic acid.
https://lowpowerlab.com/2012/12/15/c...-with-vinegar/

That would be handy, 45min etching is normal for me for using used feric acid