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

[liudengyuan]

Is anyone willing to contribute a SMD PCB file? Does it need a power amplifier?

[liudengyuan]

Has anyone done this circuit, is it very unstable, or barking, or the mineralization reaction is particularly strong? What is the depth of detection? Informed people please tell me, thank you plus thank you

[gurdal]

Hi
I made the circuit.
worked.
there was no good perception.
bs170 and irf740 burned.
Then i will look again.
for now my love idx pro

[liudengyuan]

What about this thing? It is estimated to be unstable

[F117]

Please define 'unstable' ?

[RH-Lightning]

Hi F117!

Thanks for a great project and opening it to the public!

There is a source file for V4.1 firmware on your project homepage. Could you share V4.2? I would like to compile it for >200us for bigger coil.
Board is already assembled, no time to test it out outside.. I'm looking for a simple machine to detect larger objects (axe size and above) with 50-100cm depth.

It would also be great to make it switchable from small to large coil mode on a single PIC
But the price for components is so small, that two detectors could also be made

[F117]

When you look into the source file here:
http://users.telenet.be/willaert/MD/.../v4/Pickini4.c

In the constants definitions area - in the beginning of the file:
#define TX_PULSE_WIDTH 100 // TX pulse width in microseconds

You can change this to the value you want.

[RH-Lightning]

thanks for a quick reply.

Yes, I have already found that parameter.
I was asking about the source versions. Latest is V4.2 sensitivity setting influences the comparator slicing value
Linked file is V4.1 I believe.

What does "sensitivity setting influences the comparator slicing value" do in real life?

[F117]

You can find the source file for Pickini v4.2 here - I just uploaded it:

http://users.telenet.be/willaert/MD/...4/Pickini4.2.c

The comparator slicing level is changed along with the sensitivity potmeter setting: the higher the sensitivity, the higher the slicing level of the flyback pulse.
Higher = closer to the steady state DC voltage. The closer to steady state, the more sensitive to small changes in the pulse width.
But also less stable.
You can even turn it up above steady state level, resulting in no more pulse output from the comparator and the coil error sound will signal this.
This sensitivity adaptation gives the user an extra degree of freedom.

Enjoy,
- Bernard

[RH-Lightning]

thanks a lot.
will report on experiments with larger coils/pulse width after testing.

[sinclairuser]

hi bernard, and all, i finally finished my pickini i have been going through my projects finishing them up,

.

so i got there in the end, thanks to bernard, and bruce(6666), for the chips both work great, and thanks to kosacid for the boards.

p.s. please ignore the pic below of the grubby mainboard i got in for repair the image made it into the upload by mistake i tried to remove it but it put it beneath.
thanks
aly.

[6666]

Good job, glad the chip worked ok.

[Goaty]

I've just finished repairing a friend's newly completed Pickini board and thought it might be worth relating what the problem was as it could help someone else with similar symptoms.

When the board was first fired up using a current limiting power supply set to 1A it appeared to have a dead short circuit which caused the power supply to go into current limiting. A feel of the components on the board showed that Q1, the IRF740, was the only thing getting warm and also there was no audio output.
When I unplugged the coil and again applied power all seemed OK except that after the initial auto-tune sequence it gave the coil fault tone as it should. When I plugged the coil in now everything worked fine with it detecting perfectly. At this stage I carefully examined all of the solder joints an touched up a couple of sus ones but it still would not work on power up with the coil attached.
I then checked that all of the components were fitted correctly and of the specified values - all seemed good.
After replacing the 5v reg (78l05) with still no improvement I moved on the the BS170 FET. Replacing this with a new one did the trick and everything was good.

Out of curiosity I checked the FET but it appeared fine on my tester. I have no idea why it was shorting with the coil but not without, especially since it is only driving the IRF740 which carries the coil current.

[F117]

The only issue with the BS170 I recall in this thread was mentioned by ripsdevala:
https://www.geotech1.com/forums/show...458#post223458

The BS170 is only a level converter from the 5V output pulse of the PIC to a 12V inverted pulse to the MOSFET gate.
You might as well replace it with a BC549 or a general purpose NPN switching transistor.

[bernte_one]

[QUOTE=F117;223494]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):


lot easier, take a neodym magnet and move it clos to the coil windings, feel the vibes, or maybe the sound (if you have working ears)