Voodoo Main Discussion

[MartinB]

https://www.ebay.fr/itm/50m-165-Litz...cAAOSwuHJbC-5- hong kong...
hi, i bought in this shop .. see if there is any 175/46 .

Thank you.
I will purchase from either Hong Kong or USA although this will delay the development of my coil.

[MartinB]

Hi everyone. I made 3 rx coils for the omega. 1: 0.10mm, 2: 0.20, 3: 0.25mm all three have almost the same inductance value, only their resistance changes of course, .. for the moment, it is 0.25 mm which is the most sensitive to the target size. all resonate at 9.9, 10, and 10.2khz. Tomorrow I change the capacity, to resonate at other frequencies ..

Hi Lamoiz
Contacted a UK manufacturer of litz wire today who asked me some interesting questions which led to further research into litz wire.
You will see from the attached table that 0.2mm to 0.25mm diameter conductors are more suited to our purposes and designs

[6666]

Hi George, do caps 15/18, 16/17 have to be matched ?
I am guessing not, thanks.

[ivconic]

Thanks reply, do you have your Arduino UNO R3 set up so it can program attiny 12-13-15 ? if I could do that I would be happier.

No. I started late with Attiny85, recently actually. So i am not familiar with older models.
But this question makes me "google" the net and see what is the problem.
Small flash, no SRAM, no polling; makes those impossible to program in Cpp with IDE.
Only assembly. Old way. Probably Arduino ISP with fixed delay.
Avrdude maybe.
If i had one of those; i would probably try anything from the methods.
But with affordable Attiny 85 i don't see a reason even to mention those oldies.
Especially with appearance of cheap Digispark USB dongles.

[Qiaozhi]

Hi George, do caps 15/18, 16/17 have to be matched ?
I am guessing not, thanks.

Probably not. I didn't bother and it worked fine.

[lamoiz]

Hi Lamoiz
Contacted a UK manufacturer of litz wire today who asked me some interesting questions which led to further research into litz wire.
You will see from the attached table that 0.2mm to 0.25mm diameter conductors are more suited to our purposes and designs
[ATTACH]53962[/ATTACH]

good information .thank you.

[surfdetector]

this evening I made tests at different frequencies, here is a summary of the results on a Napoleon bronze coin. the best is around 10khz. I tested on the omega; rx a 5, 7.7; 10, 15.5, 22 khz,. for gold, I have not tested. I asked a friend in MP to do the test on the f75. I will now do the same tests on the Super D this weekend.

Hi Lamoiz,
I am getting about 4.5" on a 3 gram 18k ring with standard default settings in PI mode and about 4" in Hybrid
I am getting about 6" on a 7 gram 14k ring with standard default settings in PI and Hybrid modes
The coil I am using is a Fisher F75
I conducted these readings inside my house as it is raining very hard here today so that must be taken into account as a factor.

I have yet to take my machine out to the beach as I am still waiting for a carbon fiber tube for a shaft. I prefer to do testing as part of a real hunt as opposed to using a ruler.

[lamoiz]

Hi Lamoiz,
I am getting about 4.5" on a 3 gram 18k ring with standard default settings in PI mode and about 4" in Hybrid
I am getting about 6" on a 7 gram 14k ring with standard default settings in PI and Hybrid modes
The coil I am using is a Fisher F75
I conducted these readings inside my house as it is raining very hard here today so that must be taken into account as a factor.

I have yet to take my machine out to the beach as I am still waiting for a carbon fiber tube for a shaft. I prefer to do testing as part of a real hunt as opposed to using a ruler.

thank you surf; you have very good results .. i am not at that on the omega. but since this morning I have been working on the super D, and I am slowly approaching what you get with the F75, with precision on the target. With the superD, the target is centered on the hybrid rx mode, as in pulse. This is really good. I am progressing well.

[surfdetector]

thank you surf; you have very good results .. i am not at that on the omega. but since this morning I have been working on the super D, and I am slowly approaching what you get with the F75, with precision on the target. With the superD, the target is centered on the hybrid rx mode, as in pulse. This is really good. I am progressing well.

I look forward to seeing the results with the Super DD. The Voodoo is a great project that will have much more of interest to see.

[6666]

Hi Lamoiz,
I am getting about 4.5" on a 3 gram 18k ring with standard default settings in PI mode and about 4" in Hybrid
I am getting about 6" on a 7 gram 14k ring with standard default settings in PI and Hybrid modes
The coil I am using is a Fisher F75
I conducted these readings inside my house as it is raining very hard here today so that must be taken into account as a factor.

I have yet to take my machine out to the beach as I am still waiting for a carbon fiber tube for a shaft. I prefer to do testing as part of a real hunt as opposed to using a ruler.

Could you say which F75 coil you have thanks
https://md-hunter.com/wiki/fisher-f75/

[Matt_Rowe]

i delete this double post, im trying but wont let me

[Matt_Rowe]

Have you not read the book?

no, i have to watch my money because of my chemo and bills right now, i had to retire because of this disease. so only have SSI

[godigit1]

Looks like the Voodoo pre amp is capable of sub 10 us sampling as tested in Pi mode. i was wondering if my coil was going to be too fast but its right at 7 to 8 us as the voodoo is in my testing.
The !8 dual field DD is capable of hitting a one.2 gram nugget at 4 easy inches and a two gram 10 K ring at 12" with a nice response on a MPP.
Thinking this looks good for the Voodoo if I can keep the Rx As fast.
.

[godigit1]

Hi Qiaozhi,
Can I omit the resonant capacitor in my coil if my free running SRF in my Rx coil Is 7.8 Khz ? I may try to design a free running 10 .5Khz but if I don't have to go there it would be nice .

Still trying to learn Vlf Coils.

Thanks

[lamoiz]

hi everyone, yesterday and this morning, I worked on the super D, I really get better results than with the omega, the detection distance is greater, .. which is normal, since the detection surface is also larger, it is felt on gold, and on smaller object. I will therefore now do some tests with other Rx frequencies. the same as those on omega from last week.