Voodoo Main Discussion

[SilverSurfer17]

Its cheaper for Amazon to have the post office deliver it and cost the tax payers 80 million more a year when we have to cover it Jeff is no dummy or i should say his wife was no dummy and yes we have them deliver it Amazon also every street around here has a Amazon truck on it soon drones landing in their yards i had Prime for awhile but i didn't really use it at the time so i let it expire

[ivconic]

Question for Voodoo and DB experimental circuit:
how really important is to balance RX coil with TX coil?

[Qiaozhi]

Question for Voodoo and DB experimental circuit:
how really important is to balance RX coil with TX coil?

Very important.
With improper nulling the RX loop will look like a huge target to the PI channel.

[Altair]

I believe that balance is foundamental for PI channel to ensure a good depth, despite some energy is anyway dissipate on RX coil and for that a loss of depth is endemic of this solution

[ivconic]

Ok, that question is answered.
Last question;
if PI part of the detector works at 600pps or Hz and i am trying to use White's coil with stripped caps and other components from the inside of the coil:
do i need to balance TX&RX coils to 600Hz frequency or to 6.59kHz (White's working frequency)?
I will not use White's coil.
I will use same coil arrangement and sizes as at White's coil; but i will make 360-400uH TX coil and 7-12mH RX coil.
So i need to know at which frequency i need to balance those coils?
Logic tells me that i should balance those coils for 600Hz frequency.

[Altair]

Ok, that question is answered.
Last question;
if PI part of the detector works at 600pps or Hz and i am trying to use White's coil with stripped caps and other components from the inside of the coil:
do i need to balance TX&RX coils to 600Hz frequency or to 6.59kHz (White's working frequency)?
I will not use White's coil.
I will use same coil arrangement and sizes as at White's coil; but i will make 360-400uH TX coil and 7-12mH RX coil.
So i need to know at which frequency i need to balance those coils?
Logic tells me that i should balance those coils for 600Hz frequency.

I would doing like you.
Operating frequency is driving.

[Qiaozhi]

Ok, that question is answered.
Last question;
if PI part of the detector works at 600pps or Hz and i am trying to use White's coil with stripped caps and other components from the inside of the coil:
do i need to balance TX&RX coils to 600Hz frequency or to 6.59kHz (White's working frequency)?
I will not use White's coil.
I will use same coil arrangement and sizes as at White's coil; but i will make 360-400uH TX coil and 7-12mH RX coil.
So i need to know at which frequency i need to balance those coils?
Logic tells me that i should balance those coils for 600Hz frequency.

The TX repetition rate is actually 1000pps.
You should balance the coils with them connected to the detector.

[ivconic]

Thanks Altair and Qiaozhi!

[6666]

Ok, that question is answered.
Last question;
if PI part of the detector works at 600pps or Hz and i am trying to use White's coil with stripped caps and other components from the inside of the coil:
do i need to balance TX&RX coils to 600Hz frequency or to 6.59kHz (White's working frequency)?
I will not use White's coil.
I will use same coil arrangement and sizes as at White's coil; but i will make 360-400uH TX coil and 7-12mH RX coil.
So i need to know at which frequency i need to balance those coils?
Logic tells me that i should balance those coils for 600Hz frequency.

but i will make 360-400uH TX coil and 7-12mH RX coil. why are you useing such a high inductance for the RX coil ?

Another thing I have been pondering Dave Emery says if making a PI conc then use a 22 ohm R between coil and mosfet, anybody doing that ?

[ivconic]

but i will make 360-400uH TX coil and 7-12mH RX coil. why are you useing such a high inductance for the RX coil ?

Another thing I have been pondering Dave Emery says if making a PI conc then use a 22 ohm R between coil and mosfet, anybody doing that ?

RX coil is "VLF I/B" part of the detector. Expected to be in such range.
Although not sure how it would perform with lower inductance... the RX front end.

[6666]

RX coil is "VLF I/B" part of the detector. Expected to be in such range.
Although not sure how it would perform with lower inductance... the RX front end.

I am aiming for 1.2mH from table 6.1, about 60 turns on 5 inch former, be interesting to see what happens.

[dfbowers]

Question for Voodoo and DB experimental circuit:
how really important is to balance RX coil with TX coil?

I found it to be very important because the first couple of oscillations will go into saturation and will not be useful to sample there unless gain is decreased unnecessarily. You can get very good sensitivity even at very low gain if everything is nulled.

[MartinB]

I saw the post on the three different types of cable to use ill have to order mine soon i was wondering anyone know what Minelab uses thanks or can narrow it down to whats best to use

Twin individually screened coax, but there are no markings on the cable to help identify it.

[SilverSurfer17]

That mogami coax looks nice at least the connectors and the outside of the cable doesn't look like that cheap shiny plastic so then i assume just remove the ends and replace with 5 pin connectors

[Altair]

I found it to be very important because the first couple of oscillations will go into saturation and will not be useful to sample there unless gain is decreased unnecessarily. You can get very good sensitivity even at very low gain if everything is nulled.

Do you test with deep null or not?