My Pulse Oscillation detector project.

[6666]

so I bought a PICKIT3 programmer. PICKIT 3 already supports 12F1840, but in the MPLAB IPE only the low voltage version, PIC12LF1840 can be selected.

I use MPLAB IDE 8.76 and Pickit3 and have no problem programming a 12f1840, see post #78

[waltr]

Nice build. What is the diameter of the coil?
How well does this work pin pointing in a dug hole?

The code for the 1840 is pretty complex so not easy to understand and modify.

[fekemil]

I modified the code for the 12F1840 PIC, now default Mainmode0 is distance indication.
I use this circuit as a pinpointer. Coil is D=0,75mm enamelled copper wire, 30 turns, 0,6 Ohm, 175 mH. The body is made from drain pipe, bottle neck and cap. The head is changeable. I tried with bigger searching head, but not the best for treasure hunting without discrimination. Teemo wrote: "Ferromagnetic metal target objects decrease free oscillation frequency and non-magnetic metals increase oscillation frequency" So, when the program compare the result with the reference, and the frequency is decreasing, that means the metal is ferromagnetic, and it gives a high tone output. I tried modify this part and mute this sound, but no luck. I'm not a programmer.

[waltr]

Can you post the code changed to mod1 at startup?
Or can you tell me how to do the change?

Marc

Simply change the DEFAULT mode value. Then re-build to produce a new hex file and program into the 12F1840.

        ;--------------initial MODE selection-----------------
        banksel MainState1
        movlw   .1      ;default mode

        movwf   MainState1

[Spyke]

Can you post the code changed to mod1 at startup?
Or can you tell me how to do the change?

Marc

[waltr]

I built this circuit as a pin pointer using a ferrite rod out of an old AM transistor radio. Wound 80 turn #24 enamel wire of ferrite rod.
Used the PIC12F1840 processor and the 1.80 source code. I did change the default 'mode' from 0 to 1 since this is the mode I found most useful as a pin pointer.
This circuit/PIC code works great and makes finding a target in the ground much easier.

I didn't have enough good NiCad or NiMH batteries and could not get it working with 3-AA alkaline batteries so added a 7805, TO220 regulator to run from a 2-cell LiPo (7.4V Nom). The circuit works BUT the quiescent current of the 7805 is quite high and will discharge a 1000mA-hr LiPo in a few days. This defeats the idea of putting the PIC into Sleep mode and required adding an ON/OFF switch. There are newer 7805 like regulators with much lower quiescent current so this may still work.

First picture show the circuit prototyped on a plug-board and ferrite rod.. The large 2200uF cap is REQUIRED, else the PIC keeps resetting due to Voltage drop-out.
Next pictures show the project and the point to point wired perf-board in a plastic enclosure. The ferrite rod is inside the plastic Cigar tube which is attached to the box with two screws. This makes a handy pin-pointer as the rounded cigar tube is easy to poke around in the dirt to find the target.

[fekemil]

I was looking for a simple pinpointer here and found this. The one sided circuit was easy to make though I could not get WIMA capacitor. I used another type (Arcotronics) instead. The coil is ferrite core inductor, 470uH, 1.2A.


Programming the pic was difficult for me. I got a KIT150 type programmer, but it does not fully support the 12F1840 pic. I had many unsuccessful attempts, I managed to program the hex and verify it, but the circuit did not work. I think I'm not set the fuses properly. It turns out that there has been no support for this programmer for many years, so I bought a PICKIT3 programmer. PICKIT 3 already supports 12F1840, but in the MPLAB IPE only the low voltage version, PIC12LF1840 can be selected. After the warning was accepted, programming was successful and the circuit works. It can detect 1€ in 1 inch. I'm going to try Spyke's recommended coil either. For me, it has a pretty funny voice

[chemelec]

Hello Folks,

I have downloaded the attached file, after UnZip the file, the extension (*.lay6) is unknown for me.
May I ask what software can open this kind of files? or perhaps a photo (JPEG) of diagram

Regards,

Andy

Here is the Picture.

[kt315]

this is in Sprint-Layout 6.0. a primitive cad soft for especcially lazy dummies.
take it on a torrent.

[AndyMuller]

Hello Folks,

I have downloaded the attached file, after UnZip the file, the extension (*.lay6) is unknown for me.
May I ask what software can open this kind of files? or perhaps a photo (JPEG) of diagram

Regards,

Andy

hi all
hi teemo
could you have look at my pcb and the mod i ve made about the IRL630?(pin 2 pic)
(i just want to aviod using this because it is a little bit expensive)
i saw this trick on an arduino uno output pinout so why not???
thanks

[LOONEY2008]

Hello all, this is my first post so thanks for letting me join, as a first project i saw this as ideal, just a quick question on the parts for the 47nf 400v or 630v better aqnd 5% or 20% version? cheers i found to the best i can some alternatives for the mofset that meet the requirements but also before i go ahead and purchase does a higher amp matter as long as vgs and below 5 volts operation ect meets requirements, and has anyone actually tested as a metal detector not a pin pointer as i cannot see any replies for depth as a coil not a pinpointer,
as this is my first post i would like to thank teemo for his work on this as it was his post on his website that directed me to this forum. thankyou to anyone that can help my questions.

[nick holas]

hi all
hi teemo
could you have look at my pcb and the mod i ve made about the IRL630?(pin 2 pic)
(i just want to aviod using this because it is a little bit expensive)
i saw this trick on an arduino uno output pinout so why not???
thanks

[Spyke]

Biuld this detector as pinpointer and it works perfect, I can detect 1 Euro in 7cm.
For me it works best with 470mH coil, wound with 0.2mm copper wire araound a 10mm feritte. The feritte should be longer than coil itself, for me 80mm ist perfect.
I got best detection with mode2 gradual beeping(distance indication). If the device would startup in this mode, this will be fine.
Maybe somebody can change code for me or point me how to do. I already asked Teemo, but he´s not able to do it at the moment, but he told me it wouldn´t be a big thing to do that.

[liudengyuan]

[Tim]

Hi Teemo. Good recycling there, and a nifty little circuit.
Personally I come to this site to glean simple(to you lot) information, in my quest for a sensitive, simple detector. That, to me, means zero, few, or easily substituted ic's. Preferably an all transistor design. Something that does not result in the homebuilders plethora of mistakes, as indicated by the many questions clogging this site.
To me, the point of making a metal detector is not to achieve a thinking machine, rather to simply give the most comprehensive signal to the ultimate processor, the human brain. A beep design I consider too basic for relics or gold. It should be able to be built on a printed board, or with wood, screws and cup washers, and need no manufacturers service-ever. Cosmetics are secondary, followed by bells and whistles. Battery changing/charging can be eliminated altogether by using 3x18650s, a li-ion charge board and 1w solar panel mounted on the shaft, then regulated to the desired supply.
The sensitivity you describe seems comparable to the 555 circuits online, however these commonly are squared wave BFOs(?), giving a variable sound.
So I see the 2 barriers you need to overcome is sensitivity, and monotone. The sensitivity is where I concentrate with my design, and avoiding generic beeps. Correct me if I'm wrong, but an "air" filter, is that just a radio wave receiver? And de-coupling is done this way, or with diodes, depending on the circuit??
I may not know the lingo, but that hasn't stopped me achieving great sensitivity and a powerful signal.
After all, that is ultimately the goal, isn't it?