Voodoo Main Discussion

[Qiaozhi]

I am sure it can be done easy on the same board, with just few small corrections.
RA4 should provide PWM (if possible, if not; cut existing track, disengage RA4, use another PWM pin and piece of wire... simply will do).
PWM to connect to NE555 and "bias" its threshold.
RA4 can even stay there and still switch the audio.
Few different solutions on the same board, without much of a changes.
Without me reading the PIC datasheet, a question: are there any free PWM pins?

Setting up PWM is more complicated than with Arduino, which is extremely simple but more limited.

With the PIC18F4520 you need to set some bits in the CCPxCON register, and also load the PR2 register to define the PWM period.
The equation is: PWM Period = [(PR2) + 1] • 4 • TOSC • (TMR2 Prescale Value)
There are two PWM outputs, and they both use Timer 2.

From the datasheet:
15.4.4
SETUP FOR PWM OPERATION

The following steps should be taken when configuring
the CCP module for PWM operation:

1. Set the PWM period by writing to the PR2 register.
2. Set the PWM duty cycle by writing to the CCPRxL register and CCPxCON<5:4> bits.
3. Make the CCPx pin an output by clearing the appropriate TRIS bit.
4. Set the TMR2 prescale value, then enable Timer2 by writing to T2CON.
5. Configure the CCPx module for PWM operation.

[ionut_mtb]

You are incorrect in your assumptions.
Voodoo has been built and tested outside in the real world, and it really works. The purpose of the project is to demonstrate true ferrous / non-ferrous discrimination. There is always room for further development, in which (as you can see) others are willing to participate. Before you can have an opinion (and not an assumption) you must read the book, and possibly then construct the project yourself. You may then have better thoughts on how to make improvements.

By the way, I did not write the book to make money. I simply wanted to get the technical information into print before anyone claimed the idea and tried to get it patented, and also because I found it an interesting and enjoyable experience to publish a technical book on my own. There are much easier ways to make money than writing technical books, believe me.

On the other hand, I have also built and tested Felezjoo, and was less than impressed. There are claims that it works by some principle patented by Minelab, which is not true. You can easily determine that by examining the TX waveform with an oscilloscope. Also, it relies on target conductivity to attempt to eliminate iron which will never give anywhere near accurate ferrous rejection.

I apologize, maybe my words were exaggerated. i don’t compare felezjoo with voodoo, i understand how discrimination is working on both. i just asked lamoiz about his problems with felezjoo.
I told you that i want to buy the book, and build voodoo but first i want to see one working unit, with doable coil.

[godigit1]

Easy guys, George has provided us a new experimental project, it will take some time to have a working unit and to experiment to see how it performs, I hope to finish mine in January, but then I have to make a coil for it, so vlf coils are new for me as I am a pi guy so I am finding it interesting making something new, have a good Xmas.

Hi 6666,
Me too with the Vlf coils.
.
I've noticed one thing that may help with voodoo at first observation with a homebuilt concentric.
Don't lock down the bucking wire until you monitor tp 12 and make the final adjustment to tp12) the disc Sync with no target present.

I had balanced as best as I could on a signal geny and Disc was working but not on zero on the scope. Seems like Tp 12 is a good place to do a final tweak to your coil as I only barley had to move my balance wire to 0 out.

Merry Christmas to you and all as well

[ivconic]

Setting up PWM is more complicated than with Arduino, which is extremely simple but more limited.

With the PIC18F4520 you need to set some bits in the CCPxCON register, and also load the PR2 register to define the PWM period.
The equation is: PWM Period = [(PR2) + 1] ? 4 ? TOSC ? (TMR2 Prescale Value)
There are two PWM outputs, and they both use Timer 2.

From the datasheet:
15.4.4
SETUP FOR PWM OPERATION

The following steps should be taken when configuring
the CCP module for PWM operation:

1. Set the PWM period by writing to the PR2 register.
2. Set the PWM duty cycle by writing to the CCPRxL register and CCPxCON<5:4> bits.
3. Make the CCPx pin an output by clearing the appropriate TRIS bit.
4. Set the TMR2 prescale value, then enable Timer2 by writing to T2CON.
5. Configure the CCPx module for PWM operation.

It's a start!
I will have to read datasheet.

[6666]

Hi 6666,
Me too with the Vlf coils.
.
I've noticed one thing that may help with voodoo at first observation with a homebuilt concentric.
Don't lock down the bucking wire until you monitor tp 12 and make the final adjustment to tp12) the disc Sync with no target present.

I had balanced as best as I could on a signal geny and Disc was working but not on zero on the scope. Seems like Tp 12 is a good place to do a final tweak to your coil as I only barley had to move my balance wire to 0 out.

Merry Christmas to you and all as well

Hi GD, I have found this thread to have some good info and tips, I think my plan will be 10 inch TX, 5 inch RX and bucking, will try and 3D print a duel RX and bucking former as per dbanner tip.
https://www.geotech1.com/forums/show...ight=tgsl+coil

[SilverSurfer17]

I wanted to overclock the processor they can be ran way faster and still be stable as for the reasoning I have no idea I figured a faster detector so I can walk faster with it I guess it?s called bounce back and like I stated that the fool from another planet didn?t read I?ve never picked up a detector or invented a circuit I?ve stuffed some boards using a built board as a model and ran thousands through a wave soldering machine that?s it but I could give 2 squats if I fry the chip putting a 80hrz crystal change a resistor to get 6v and mess with the baud rate or even build a separate timing circuit I?m building this to learn what happens when I do this or that to it

[SilverSurfer17]

Also when I asked that what I was trying to figure out was how to get more voltage and amperage to the coils and figured I’d start from what had the lowest voltage rating not knowing what a mosfet does I’ve touched thousands of them but had no idea what they did besides burn the crap out you if you touch one I’ll learn on my own I guess I’ll just sit back and lurk instead of being insulted because I will defend myself and I will hurt some feelings and get booted even if anyone can just make another account

[SilverSurfer17]

I’d like to know if there is a way to put leds in a row on the left side that’s red and green ones on the right side like the graph on the screen for iron or precious metals so you know with lights blaring you in the face instead of having to look at the screen I want to be able to crank the volume to the point it hurts my ears I’d like to be able to make 24volt 18650 batteries for it I’d like it to be able to be mounted different ways like a coil off the back of a e scooter and mount the unit on the bars and build a big coil so I can ride a mile a hour and pick up signals and ignore garbage signals and I might be from another planet but from what I’ve seen I know all that can be done

[SilverSurfer17]

I mean you guys are suppose to be experts whats the limits for voltage amperage to coils I know with Tesla coils more voltage amperage the better the coil is tuned to the caps the better it performs and I know it has to be true with MD because they have stuff like those two boxes that detect feet into the ground instead of inches so whats the limit in these handhelds traces on the boards caps resistors transistors all of the above I assume all that can be made stronger and Im not worried about battery size

[Qiaozhi]

I mean you guys are suppose to be experts whats the limits for voltage amperage to coils I know with Tesla coils more voltage amperage the better the coil is tuned to the caps the better it performs and I know it has to be true with MD because they have stuff like those two boxes that detect feet into the ground instead of inches so whats the limit in these handhelds traces on the boards caps resistors transistors all of the above I assume all that can be made stronger and Im not worried about battery size

Please put your thoughts in separate thread, as none of this has anything to do with the Voodoo Project.

[SilverSurfer17]

Whats faster a mosfet or a solid state relay do either one affect a signals frequency because of the speed of either I dont know but Ill blow some stuff up to find out if I have to Ill build a damn board with just those parts to test it and find out if raising the voltage and amperage with both changes it and learn from it

[SilverSurfer17]

I read that to detect for silver look for a detector that works on 5khz now is that the tuning of the coil or the timing of the pulses or what that makes a detector work on that frequency more then another I assume it’s the windings in the coil then what works better on lower frequencies fast pulses slow pulses one big blast pulse multiple ?

[SilverSurfer17]

How hard is to change those frequencies that it?s more tuned for like I live in Illinois I don?t expect to find much gold but I know I will find silver so can I set it up for 5khz for here then when I go the beach in Alabama to my Parents can I set it high for other metals like gold with just another different coil and have a way to switch it without having to change stuff on the board

[SilverSurfer17]

All of it does considering I bought your board and $150 in parts for it and I’d like to do all of it

[SilverSurfer17]

I’m just curious what this forum is for if not to ask questions about it and you your self said you want to see what can be done with it that’s what I want to do and any help doing it would be greatly appreciated like the led idea