Question for Dave J

[Frank-S]

Dave, I am still working on a VLF coil for my Troy X5.
I am up to 16 -- 17'' on a US nickel (17'' DD coil) I have a noise
problem.is there a way to filter out the noise other than a shield..
in one of George Payne post on on this forum he to put a 0.47uf
cap on tank is that for noise.
is the tank TR or RX coil,also is the cap put in line or across coil.
Thanks Frank.

 

[Dave J.]

I don't remember the L,R spex for the Troy X5 searchcoil, somebody over on g-tech probably has that info. No capacitors in searchcoil.

Big searchcoils pick up more magnetic field electrical interference, and no you can't shield it out. You do have to provide electrostatic shielding: this is normally done with carbon loaded conductive paint, ohmmeter resistance 100 to 1,000 ohms when dried.

--Dave J.

 

[Frank-S]

Thanks Dave what are caps for in other detector coils.the x5 only makes a noise when i
touch cable,controal box or coil.I tryed spray paint shield.
Thanks any way i will keep at it.

 

[Dave J.]

Thanks Dave what are caps for in other detector coils.the x5 only makes a noise when i
touch cable,controal box or coil.I tryed spray paint shield.
Thanks any way i will keep at it.

The Troy X5 searchcoil is entirely conventional, no special secrets.

As with all searchcoils which use shield paint, the shield paint has to be electrically connected to a ground. Usually that's analog ground but sometimes it's the negative rail. In most designs either ground will work.

The Troy X5 runs at fairly high gain, and therefore induction balance is more critical than it is on some other machines.

Some other detector coils use capacitors for some combination of transmitter coil resonance, receive coil resonance, trimming inductive reactance, and/or trimming reactive offset. A resistor is sometimes used for trimming resistive offset or for other reasons.

 

[Frank-S]

Dave, I found the noise problem,the shiled cable from coil to box was cause it.
I removes cable and replaced it with a non shield cable.the coil did lose some depi
i need to get it back pluss more depi. 2 more questions
1) Is there any way i can boost TX and RX with a resister and cap.
2) yearsm ago when the first Gold BUG detector came out it had a problem,if
you waved your hand over the coil it deteceted your hand.
Do you know what was don to solve problem
Thanks

 

[Frank-S]

Dave I dont need a reply.
The 17'' DD coil dont detect my hand any more.Tryed the coil out in
my yard.I did not put enough shield,if it touches a blade of grass it will
let me know..17'' DD coil is very hard to pin-point with it detects a can about
2 ft on each side of coil and about 3 ft above.now i know
Think that I will go back to concentric, this is more of a challenge,than swingeing
a coil looking for a rain-bo
Thank for your help.