PIC12F675 VLF

[bernte_one]

Hello,

not sure if it will work but what did you think?

[golfnut]

Hi, put the schematic up please S

[Waikiki_Sweep]

I was so curious about this detector so I have redrawn schematics from PCB.



Finally it appears to be some cheap VLF that using only amplitude of signal in RX coil to detect target.
Because no phase readings so there is no discrimination and probably no ground balance, as I can understand.

Good for the guys who love to run in "all metal" mode with their VLFs (and even multifrequencies like Fisher CZ or Excalibur).

But what reason to make simple VLF detector with complicated (balanced) coil if it is much easier to make simple PI detector with simple mono coil.

Hope some schematic blocks will be useful for further design of something more practical.
(Someone add ground balance and target ID to this detector )

[Tepco]

This is actually not typical VLF, but some sort of off-resonance pinpointer probe, with this amplitude detection. Much better way to utilize PIC for this purpose is building, for example, Russian “Maljish FM” probe, simple and known to work.

[Eddy71]

No, it's not "MalyshFM2" is RX/TX.

http://translate.google.com/translat...-1-0-3&act=url

[Tepco]

I meant this version :http://www.md4u.ru/viewtopic.php?f=8&t=3602

[Eddy71]

Look Waikiki_Sveep scheme. There is shown a transmitter and a detector . In "KidFM" is only a LC oscillator. This BFO.

[Tepco]

It is not BFO but FM, well, similar, original schematic on this thread is not classic VLF but balanced coil off-resonance detector. All about best utilization of PIC.

[bernte_one]

hello
i have mounted all components and made first test
and must says yes it works
easy to adjust
balancing tx rx coils is very easy made by tone indication
or measuring induced voltage on rx

i have changed the resistor 39k to a pot with 100k for more gain

the detector hhas following functions
s2 for setting the threshold barrier also jused as a pinpointer if you get closer to obejct press s2 button and the new barrier it set more down
s1 on off switch should be combined with a reset pushbutton (disconnector)
pot 100k for gain(sens) adjust

all works fine with a small enclosrue and a single 9v block

not depth but i sure i will find some points for improvements

btw has anybody some suggestions to pump more power to the tx coil

if i calculated right with the frequency it works in the common 1/ 1,2 freqeuncy shift tx/rx as i know it from tesoro projects here but around 6khz area

kind regards

[bernte_one]

had time to made a video
http://www.youtube.com/watch?v=tbRtS...ature=youtu.be

i hope to get some comments
think there ist some space for improvements
it is very basic but it fits to most beginners (in electronic and metal detecting) because it is so easy

good night

[ivconic]

"...btw has anybody some suggestions to pump more power to the tx coil..."

Lower R3 and rise R4. It will affect power a bit, not much but a bit.
Try to experiment with R7 too, lower it.
Q1 can be some higher gain, maybe?
And that's about all what you can try with present setup.
I am interested in the design but not in that version.
I prefer simpler version with one coil, to serve me as ppointer only.
Has anybody made it as pp? Any video?

[Tepco]

had time to made a video
http://www.youtube.com/watch?v=tbRtS...ature=youtu.be

i hope to get some comments
think there ist some space for improvements
it is very basic but it fits to most beginners (in electronic and metal detecting) because it is so easy

good night

Not bad at all for such a simple device. From where you get .hex file for PIC, is there any website related to this project? Maybe basic for detector, but looks like very good starting point for decent pinpointer probe.

[6666]

I wonder if a full wave rectifier in the RX would make any difference .

Could you please tell us your coil specs thanks.

[Qiaozhi]

Not bad at all for such a simple device. From where you get .hex file for PIC, is there any website related to this project? Maybe basic for detector, but looks like very good starting point for decent pinpointer probe.

The problem with this design is going to be a lack of ground balance capability. It will work fine in an air test, but bringing the coil close to ground will kill the sensitivity to non-ferrous targets, unless you can keep the coil parallel (and a constant distance from) the ground.

[6666]

bernte_one

I have see your youtube video
http://www.youtube.com/watch?v=tbRtS-yrzJQ

Could you please post a link to the software for this project.

Is there any more construction information located anywhere on the net ?

thank you

I am trying a google translation, I hope it translates ok

bernte_one

Könnten Sie bitte einen Link auf die Software für dieses Projekt.

Gibt es noch mehr Bau-Informationen überall im Netz befinden?

danke