Question about the Minelab Sov and Elite

[Beachcomber]

Does anyone know how Minelab manages to get target ID info directly from the coil on these two machines. I was always under the impression that there had to be some signal processing before you had target ID info available but Minelab has somehow managed to get just by using a voltmeter to measure the voltage on the recieve windings of the coil. Any info as to how they are doing this would be appreciated!!!!

Thanks

Beachcomber

[Sean Goddard]

Re: Question about the Minelab Sov and Elite

The target ID is not simply by measuring the voltage across the coil, as an MF signal is what comes back from this.

The target ID is produced by some very pricise timing measurement and comparison within the control box (see the patents page).

Failing this I will email you the PDF od the Sov patent this weekend.

Interesting note to all:

Look at the RX signal DIRCTLY on the head connector, and try various targets (ferrous & non-ferrous) look at how the two sets of frequency square waves react to different items with varying ferrous content.

The above MIGHT give a few of you some neat idea about a so called MF project for this forum ;-)

[Beachcomber]

Re: Question about the Minelab Sov and Elite

That's what I originally thought to. But many people are buying off the shelf digital multimeters at places like Radio Shack and setting them on the 2 volt scale connecting them across the same two coil wires that minlab uses for thier meter an they have instant TID meters with a 0-200 scale instead of Minelab's 0-550 scale. This is not something that you can do with any other detector that I know of. But then I am sure there are plenty of detectors I haven't heard of out there.

HH

Beachcomber

[Mr.Bill]

Active circuit in coil.

Minelab is able to get a volt meter to work as a TID in the coil lead because they, (Minelab), uses a active circuit built into the coil. There reading the voltage changes going to the active circuit built into the coil.

Mr. Bill



Surfscanner Detector's

[Sean Goddard]

Re: Question about the Minelab Sov and Elite

What the are actually doing is using the internal voltage (target" sisgnal generator that drives the original Minelab meter.

this is between the CENTRE pin of the cconnector from the control box and the TX ground line.

Looking at the signal from the head, there is no way that what you suggest would work without some form of signal conditioning.

The Sov gives it's target ID voltage out on pin 6. This is a "stabilised" (yea right) voltage, the magnitude of which is supposed to be proportional to the CONDUCTIVITY of thhe target. So, the higher the voltage, the LESS ferrous in nature the target is, in theory.

[Sean Goddard]

Re: Active circuit in coil.

The circuit in the head is merely a preamp, and is placed in the head to minimise the amount of noise pickup in the head lead. it does NOT (as far as I am aware) do anything other than amplify the return signal from the head.

Amplifying at source is a VERY effective way of reducing noise.

The DC TID signal is generated INSIDE the control box, as if you look at the head lead, the centre pin is not used, whereas in the control box, it is fed OUT to the meter. The meter just happens to be inline.

Minelab did this to confuse people and those trying to make their own meters. Shame (for them that is)that some smart person like those on this forum saw through their little attempt to disguise their methods.

I built a PI in which the TX amp, AND the RX amp were both in the head, and it was a very quiet and stable machine...Deep too!!

[Mr.Bill]

Re: Active circuit in coil.

I haven't done any work on them, but I was aware that there was a circuit in the coil.

I was just, (perhaps not so correct), assuming that they used a tap off of that signal source.

Bill

[Beachcomber]

Re: Question about the Minelab Sov and Elite

Thanks Sean, I always knew that there had to some signal conditioning so that TID info could be determined. It always seemed strange that it could be had at the coil wires. I was thinking in terms of returned signal rather than Minelab feeding the TID signal out through the coil connnector on an otherwise unused pin for use with it's meter. You've got to watch those Aussie's every minute as you never know what they are going to come up with next

Thanks

HH

Beachcomber

[Beachcomber]

Re: Active circuit in coil.

According to Minelab's Website that active circuit in the coil is the Transmitter. If you go to thier website and read about the Elite it states that the transmitter is in the coil. So if that is true and all Sov and Elite coils are intercahngeable then all the Sov and Elite coils must have the transmitter in the coil. Either that or Minelab is trying to pull the wool over our eyes!!!!

HH

Beachcomber



Minelab's Website

[Beachcomber]

And the debate goes on

Over the years I ahve heard many people say that the circuit in the coil was a Rx Preamp and as Sean said that would make sense since placing the preamp at the coil would reduce the noise level. But as in my Post above Minelab says it's the transmitter and not a Rx Preamp. I have never taken a Sov coil apart so I have never seen the Circuit Board up close adn personal so I can not even take an educated guess as to which it actually is.

HH

Beachcomber

[Sean Goddard]

Re: Active circuit in coil.

Baaaaaaa ;-)

[Solmer]

Re: Question about the Minelab Sov and Elite




Hi, here are the pics of coils (inside), pcb-preamp is based on the lm394.

Thanks to Peter for the pics he sent them a few months ago.

...I'm interested in sovereign/elite coil building,if somebody is interested too please email me, I want to exchange ideas about that.

Good Luck.

[Carl]

Re: Active circuit in coil.

>...then all the Sov and Elite coils must have the transmitter in the coil.

I have a Sov Pro, and an Explorer. I can probe the transmit waveform with the coil connected, or completely disconnected, and get the same results. The TX signal is a digital multi-period waveform which, by the way, is identical on the Sov and Explorer.

The coil circuit might do some kind of additional processing to the TX waveform, but I would guess not, and assume that the coil circuit is a RX preamp.

If the folks who wrote that bit about the coil containing the TX circuit, are the same ones who write the Minelab advertising, then that highly suggests it's B O G U S!

- Carl

[Beachcomber]

Well that sure doesn't look like the Tx section!!!

Guess they are trying to fool us on thier website!!!!

Thanks

HH

Beachcomber

[Beachcomber]

Thanks Carl you are probably right about the info on the website!!!!

n/t