Voodoo Main Discussion

[godigit1]

Could you clarify the winding directions please

Hi 6666,
I think I have to do some experimenting to see if this could work. It was mainly a thought experiment but I'm in coil mode and I cant stop thinking about it.

[godigit1]

It's a bit difficult to follow the wiring in your diagram. Can you make it a bit clearer?

Something like this. I was thinking wrapping the dual field part as you would normally except to a d style inner coil. The wraps of the inner coil could be played with a bit to get a lower transformation ratio between ds to act as a bucking coil I'm thinking and or that wont matter if it balances out like a regular DD the later preferred. the Rx DD of course would have to be phased properly.

I have enough coils around to do a experiment thinking might throw something together and see if I can get it to null.
No small DDs so I may go 12" outer round and 4" double OO for the DD portion since I have them.

Thanks again for All this .

[6666]

Hi Qiaozhi,
Been thinking about the dual field thing and wondering if you thought this configuration could work?
[ATTACH]53735[/ATTACH]

Thinking that maybe we could get the benefits of a dual field in pi mode and give it a larger detection area and while in hybrid mode the possible benefits of a DD for separation of targets.

Could you clarify the winding directions please

[MartyJ1963]

Hi All,,,Found time between repairs to install STEP 1:-The Voodoo Power Supply and TP1,TP9,TP14, TP15 + PL9. STEP 2 will be The Transmitter Circuit. Regards, Marty.

[Qiaozhi]

Hi Qiaozhi,
Been thinking about the dual field thing and wondering if you thought this configuration could work?
[ATTACH]53735[/ATTACH]

Thinking that maybe we could get the benefits of a dual field in pi mode and give it a larger detection area and while in hybrid mode the possible benefits of a DD for separation of targets.

It's a bit difficult to follow the wiring in your diagram. Can you make it a bit clearer?

[godigit1]

I don't think you could have a dual-field coil that has a concentric RX loop. At least I've never seen one.

Hi Qiaozhi,
Been thinking about the dual field thing and wondering if you thought this configuration could work?


Thinking that maybe we could get the benefits of a dual field in pi mode and give it a larger detection area and while in hybrid mode the possible benefits of a DD for separation of targets.

[MartyJ1963]

@Godigit,,,Thanks for the tip! Regards, Marty.

[godigit1]

Thanks George. I think I came across some Van Damme 4-Core screened microphone cable (6mm) that I may purchase. Thanks again. Marty.

Be careful when using microphone cables. the ones ive used have a two layer insulation at least it looks that way.
The outer layer is black and is a conductive plastic of some type. I think its part of the shielding of the cable.
as long as its away from your solder joint Ive had no problems.
I've been meaning to check if it was connected to ground in the mic connector.

[MartyJ1963]

Thanks George. I think I came across some Van Damme 4-Core screened microphone cable (6mm) that I may purchase. Thanks again. Marty.

[Qiaozhi]

Thanks for the Dual field coil answer George. What's the best cable I can purchase for the Voodoos Coil setup please? Thanks, Marty.

You could use two separate single-core RG58 screened cables (as suggested by lamoiz) or a twin-core screened cable. I've successfully used E648E twin-core noiseless microphone cable.

[lamoiz]

Thanks for the Dual field coil answer George. What's the best cable I can purchase for the Voodoos Coil setup please? Thanks, Marty.

2 * RG58 ..no ??

[MartyJ1963]

Thanks for the Dual field coil answer George. What's the best cable I can purchase for the Voodoos Coil setup please? Thanks, Marty.

[lamoiz]

I had intended to do that, but I live a long way from the nearest beach and Covid restrictions prevented me from going there. However, the PI mode will definitely work in the wet sands. Since an audio response depends on both the PI and DISC channels responding at the same time, I have every confidence that there won't be a problem. Remember that false signals from a VLF detector in wet sand are caused by the GEB channel, not the DISC channel.

thanks George,
certainly in PI mode no problem, I hope to be able to test the "hybrid" mode. we too in France are confined, and it really takes a long time. it gives me time to finish this system .. and to do it very well ..

[6666]

I think that in the picture the Green bucking coil is actually sitting on top of the Blue RX coil. If so, that enables you to adjust the Green bucking coil, which makes the connections shown to be correct.

correct,

[surfdetector]

hi 6666
i am thinking you must connect the end of the red wire to starting of the blue wire not the green.
in this case that is difficult to nulling the concentric coil and you cant add or reduce laps the green wire for best inductance and best nulling .

best regard
zakari

I think that in the picture the Green bucking coil is actually sitting on top of the Blue RX coil. If so, that enables you to adjust the Green bucking coil, which makes the connections shown to be correct.