Voodoo Main Discussion

[MartyJ1963]

Thanks George. Just making sure I've got everythng in order before I begin and I'm also waiting on some 79L05's. After the power supply, what would be the next stage to install? Or is it ok to Install all other components after that step? Thanks, Marty.

[6666]

Thanks George. Just making sure I've got everythng in order before I begin and I'm also waiting on some 79L05's. After the power supply, what would be the next stage to install? Or is it ok to Install all other components after that step? Thanks, Marty.

Which coil did you decide to go with ?

[MartyJ1963]

Hiya 6666. I made a few different templates. Two templates are based on Georges 'Small' coil size and inductances,,I'll be making 2 different RX coils for each of them and 2 different TX Coils,,,so I can change and swap them around to see which configurations work best. One RX will be 467uh x 0.18mm enamelled wire and the other will be 467uh x 0.25mm. One TX will be bundle wrapped 0.5mm 600v PTFE 16 strand at 306uh. The other TX Coil will be made of the same wire and inductance but I'll be wrapping it as a 3DSS to see if there's any difference with it having lower capacitance. Really looking forward to all the coil experimenting on this project because it allows a lot of different coils to be used. I thought I had all the components ready to start today but still waiting on 79L05's,,Hopefully they'll arrive in the mornng. Regards, Marty.

[6666]

Hiya 6666. I made a few different templates. Two templates are based on Georges 'Small' coil size and inductances,,I'll be making 2 different RX coils for each of them and 2 different TX Coils,,,so I can change and swap them around to see which configurations work best. One RX will be 467uh x 0.18mm enamelled wire and the other will be 467uh x 0.25mm. One TX will be bundle wrapped 0.5mm 600v PTFE 16 strand at 306uh. The other TX Coil will be made of the same wire and inductance but I'll be wrapping it as a 3DSS to see if there's any difference with it having lower capacitance. Really looking forward to all the coil experimenting on this project because it allows a lot of different coils to be used. I thought I had all the components ready to start today but still waiting on 79L05's,,Hopefully they'll arrive in the mornng. Regards, Marty.

Sounds like a good plan, be interesting to see your result.

[surfdetector]

Thanks Alec. Have you started building yet? Regards, Marty

I probably won't have my board for another 10 days, it takes a long time for delivery.

[Qiaozhi]

Thanks George. Just making sure I've got everythng in order before I begin and I'm also waiting on some 79L05's. After the power supply, what would be the next stage to install? Or is it ok to Install all other components after that step? Thanks, Marty.

Fairly obviously you should start with the power supply, then proceed in this order:

1. Install the PIC and program it with the hex code from post #1. You need to have the PIC working, otherwise there will be no +5V supply. This is because the oscillator for the voltage converter comes from the PIC.
2. Install the transmitter circuit and test that it's functional.
3. It would probably be worth connecting the LCD and menu buttons at this stage, and flipping the detector into PI mode.
4. Build the PI preamp and check that the detector is working as a PI with a mono coil.
5. Proceed to build the rest of the PI channel and the audio amp. At this point you should have a working PI detector.
6. Build the DISC preamp.
7. Connect a concentric coil and test the DISC preamp output.
8. Flip detector into Hybrid mode, and build the DISC channel. You should now be able to test the hybrid capability.

Refer to page 31 for the relevant waveforms.

As with the MPP and Baracuda designs, you won't get much sympathy if you simply populate the whole board and then say: "It's not working, what's wrong?".

[godigit1]

Qiaozhi,
Thanks for the awesome work on your project. Congratulations.

I had sometimes thought of combining a GM 3 and a Pi but more in the in the way of the Grizzly Twins.
I've read most of it and great job, with your excellent detail of the journey I think even I can build one.
I ordered boards and pics and am sourcing parts.
This will be my first VLF and first Pic Board so let the fun begin!!

Thanks Again for Sharing your Project.

[godigit1]

Hiya 6666. I made a few different templates. Two templates are based on Georges 'Small' coil size and inductances,,I'll be making 2 different RX coils for each of them and 2 different TX Coils,,,so I can change and swap them around to see which configurations work best. One RX will be 467uh x 0.18mm enamelled wire and the other will be 467uh x 0.25mm. One TX will be bundle wrapped 0.5mm 600v PTFE 16 strand at 306uh. The other TX Coil will be made of the same wire and inductance but I'll be wrapping it as a 3DSS to see if there's any difference with it having lower capacitance. Really looking forward to all the coil experimenting on this project because it allows a lot of different coils to be used. I thought I had all the components ready to start today but still waiting on 79L05's,,Hopefully they'll arrive in the mornng. Regards, Marty.

Hi Marty,

I'm waiting on boards still and have some learning to do about Pics so my build will be slow but was going to start coil prep as well.

I was thinking the same as you about the outer coil and trying a 3D coil. this will also be my first concentric coil build.

For the inner coil I was thinking a vertical stacked layered planer coil with the bucking coil made on a paper form that will slide on the outer surface for nulling. Thinking 350 uh outer not sure about the inner coil yet but thinking of staying below 2mH.
Wish you luck and look forward to your testing.

[MartyJ1963]

@6666,,@Godigit,,,Thanks for your replies. I will be documenting every stage of my build, more so as a 'Learning/experience curve for myself but then, if I do everything correctly, it will maybe help others in some way or another. Thanks George for the guidance on the order of steps to take to build this exciting project. I more or less got the order of build correct to your explanation above so I'm really pleased with myself up to this point. The 3DSS Outer (TX) coil I plan to build may be a bit tricky when it comes to calculating the amount of turns for the Bucking coil because, as we know, it takes a lot more metres of wire winding to get the same inductance as a circular bundle wrapped coil. I know the ratio of, say, an 8" outer coil and an inner 4" coil is 4:1 but if the outer coil is a 3DSS then It'll have to be a matter of just adding turns around the RX until a null is achieved. Like I say, I will be taking notes, photos etc of all my coil experiments to see where it leads. @Alec and @Godigit,,Hope your PCB'S etc arrive soon,,,It'll be great when there's more people busy with this so we can exchange info between each other on our individual builds. I received 2 x Pre-programmed chips from Andy (Silverdog,,Big thanks!) so that saved me a big headache! Lol, 'STILL' waiting for 79L05's,,,then I can start!,,Thanks again George for a great new Project!,,Much appreciated. Regards, Marty.

[MartyJ1963]

Hiya George,,I forgot to ask,,Regarding the 'Waveforms' on Page 31 - Is there any chance you would be able to post the diagrams,,,I'm really struggling to read them with them being so small and even though I have scanned them at 600pi a lot of the writing etc still isn't legible enough. Thanks again, Marty.

[MartyJ1963]

@Godigit,,,Do you have any pics of what a 'vertical stacked layered planer coil' looks please? I've never heard of one but it sounds really interesting! It may give me some more ideas too. Thanks, Regards, Marty.

[godigit1]

Hi Marty,


this is the first one Ive built, in the picture everything is over wrapped a few turns.
Final #s are 30 awg 40/46 wire 27 turns 4" I.D
Tx 385uh Rx 2.04nH. 30 awg magnet wire. 8" I.D
Bucking coil ended up 6and about 34 turns with a final null at 0 to 800uV.

One down .

[godigit1]

That's 8 inch Tx 4 "Rx
Sorry

[MartyJ1963]

Thanks Godigit,,,Appreciate it. I understand what you mean now,,,It's given me some ideas now to try out with the 16 strand wire I'll be using for my 3dss. I'll be logging everything I do and keeping a record so I'll post my results as I go along. I still can't start building yet as those 79L05's still haven't arrived yet,,they should've been here over a week ago. Thanks again for the pics and data. Regards, Marty

[MartinB]

Sounds ideal for UK detecting where most of our available land is agricultural and heavily infested with deep iron such as plough points, horse shoes and other ferrous items. I will be interested to see if the Voodoo can detect a desired target which sits next to a ferrous object and also the recovery time from detecting a ferrous object to detecting a desired target.