RELIC HAWK

[Ultimate_Haze]

Hi,

Hi,
Max and all folks.
I am londering why you use NE5532?I can see on musketeer NE5534!!!

[KingJL]

Hi,
I've checked at pin7 U2, it gives 50% duty cycle always when rotating geb pot.

When rotating disc pot I get about 5° on state increase in tON time.

Kind regards,
Max

That's about what I see in simulation. The variance I see at the DISC is toward the maximum DISC setting. Toward the mid to lower settings, I see 50% duty cycle.

Could this imbalance at the higher DISC setting be causing your anomallies?

I have found that a little fine tuning of the R & C values in this phase shifting circuit can minimize the variances. As yet, I have not found the 'perfect' combination. A lot depends on the amount of phase shift needed to achieve GB. The quality and tolerance of the capacitor and resistor used in the pre-amp (2.2n & 470 ohm in the high pass filter network of the inverting input circuit) can affect the phase shift of the pre-amp and thus the phase shift required for GB.

Regards,
J. L. King

[tiktak]

Hi,

Hi,
Max how are you?
U3 and U4 are still both 4066 on the schematic!!!
We can see clearly on Musketeer that there are two TL074!Could this be a lead?
And I dont see TS27m2?

[Max]

TGSL and recent Spectrum can also be fooled ocassionally with deep iron .
Luckilly not often case, but sometimes they do.
At Spectrum problem is less due nice VDI bars. When this occurs i get bars at both sides of zero, usually highest and lowest bars are rising.So there is good base for doubts. But with TGSL situation is worse, lot of doubts about detected item. Yet it is not so oftenly. Usually medium sized iron item at more than 30cm deep in ground will fool out TGSl easilly. Large iron item is easilly recognizable by specific sound, even when it break through discrimination. It's got "metalic", flat "bang" instead soft "beep" usuall for good metals.
But medium sized iron items are nightmare, almost identical "bleep" as on good coin! Again, all these only on metal under 30cm in ground...
Small iron items are totally rejected from coil surface up to full range of detection, no problems with those at all....rusty nail...joke for TGSL as well as for Spectrum...
I think this is mostly due uneprfect coil we made...? Or...?

Hi Ivconic,
you're right... but all this happens on soil.

When testing on the bench... my TGS or TGSL run ignoring any soft iron in size of a 200gr hammer head... both from near and from far.

The RH clone I've made, instead, behave bad way with same iron stuff on distances starting from about 15cm: that's really impressive that a piece of iron sound like a copper coin at such distance... and sure it's a really worse problem that could make cloned device totally unreliable about disc on real soil.

I'm sure problem could not be so big at real, original ML RH but this happens in cloned and coinseeker too as I read.

Mistake in schematic ? Special components involved ?

I don't know...

Kind regards,
Max

[Max]

I'm afraid that this is true for some detectors. For instance, some of the Fisher's have this problem. They can be great for finding really deep nails!

Hi,
this is a really sad news... do you belive the problem I'm experiencing at disc is related to the smaller coil I'm employing at now or enhanced by it? (it's 11'' DD)

I hope the RH isn't part of that scenario of "deep nail finders"...

Kind regards,
Max

[Max]

Max,
What does the output from the Discriminator gate (U2 pin 7) look like? In simulations, I see that it is unbalanced for some settings of GB/DISC. Seems to come from DC offset at U6 pin 7. The gate shout be equal in on off times. If it is not, that play tremendouse havoc with discrimination.

Still researching!

Regards,
J. L. King

Hi,
I've checked at pin7 U2, it gives 50% duty cycle always when rotating geb pot.

When rotating disc pot I get about 5° on state increase in tON time.

Kind regards,
Max

[amtech2005]

RELIC HAWK

Eclipse , It will be interesting to see what the final "winning bid" is !!! And yes the U.S. Dollar will be getting worse and that's being optimistic. Anyway , I get the feeling that the Relic Hawk we see posted has had some "Heavy Use". Just from Looking at the photos , the detector housing front plate is very dirty . What is wrapped around the discrimination Knob ?? "Excellent Condition" ???????.....I see dirt on the search-coil also. There will be other Minelab Relic Hawks ,maybe perfect condition with a better starting price. If you blow up the pictures a little you will see the dirt. I never noticed that earlier today !!.....Eugene

[eclipse]

It's not 199$ but british pounds, which is 1.9 times more so that makes it around 400$ and this is just the starting price.The detector won't go below 500-600$ since the metal detectors are not cheap in the UK as we all know. I suppose everyone with good positive feedback from europe could ask the seller to ship it outside the UK.

[amtech2005]

RELIC HAWK

Only 3 days 19 hours left on EBAY-UK , But you must live in the U.K. !!! That rules me out !!!!! ........Minelab Relic Hawk , $199.00 starting bid and $19.00 shipping to UK only . Excellent for Treasure/Reliic Hunting and for PCB/ circuit Board "PART NUMBER VERIFICATION"..................Eugene

[ivconic]

TGSL and recent Spectrum can also be fooled ocassionally with deep iron .
Luckilly not often case, but sometimes they do.
At Spectrum problem is less due nice VDI bars. When this occurs i get bars at both sides of zero, usually highest and lowest bars are rising.So there is good base for doubts. But with TGSL situation is worse, lot of doubts about detected item. Yet it is not so oftenly. Usually medium sized iron item at more than 30cm deep in ground will fool out TGSl easilly. Large iron item is easilly recognizable by specific sound, even when it break through discrimination. It's got "metalic", flat "bang" instead soft "beep" usuall for good metals.
But medium sized iron items are nightmare, almost identical "bleep" as on good coin! Again, all these only on metal under 30cm in ground...
Small iron items are totally rejected from coil surface up to full range of detection, no problems with those at all....rusty nail...joke for TGSL as well as for Spectrum...
I think this is mostly due uneprfect coil we made...? Or...?

[tiktak]

Hi,

Hi,
Qiaozhi!
Why you dont help here insteed making funny conclusions!?
I now that you love Nexus.I havent experiance from any kind with this bulgarian detector.But be shore RH is very deep indeed!

[Qiaozhi]

That's unbelivable stuff... that one needs to put near and near the iron to get it ignored. Is the opposite of other detectors!

I'm afraid that this is true for some detectors. For instance, some of the Fisher's have this problem. They can be great for finding really deep nails!

[KingJL]

in S mode it's almost fast enough... in M mode is still OK, unfortunately the L mode doesn't work at now... or, well, is too unstable to check... but I think this is the worse mode in this machine.

But what should I do now ?

That's the real question... cause I've tested about everything about disc and cannot stop that dang iron response from far away! Is the circuit designed for this ?

From simulations and real measures I get same stuff... so I cannot explain why, even if coil is wrong, I get iron ignoring from very near and detection from far away ?????????????????????????????????????????????????? ??????

Max,
What does the output from the Discriminator gate (U2 pin 7) look like? In simulations, I see that it is unbalanced for some settings of GB/DISC. Seems to come from DC offset at U6 pin 7. The gate shout be equal in on off times. If it is not, that play tremendouse havoc with discrimination.

Still researching!

Regards,
J. L. King

[tiktak]

Hi,

Hi,
Max.
Its still mistery for me.But its look like the detector need to be ground balanced well so it can be operational.I dont see how you can achive this at home.I mean real soil.
Because on my last trip I have dugg a lot of iron!I mean those nasty halfs of horse shoes!This were madness for TGS too.But I never sucseeded to ignor them or be shore that this is trash with TGS.And now I am a little bitt confused because last time I have dugg 5 EXTREMLY deep coins.And I have pssed over the same place both times.But now the good sounds were Iron.Even the disc were set to 5 .So we will have to wait for next tests.
I am woried because Ivocnic tell me that when RH is set the right way,this halfes of horse shoes are funny game for capabilities of this device.So?
Ivica please give opinion here.
I will try to make side A for Eclipses pictures.
See you soon

[Fred]

Fred: what about your PCB , still troubles on components ?
Kind regards,
Max

Hi Max,
The problem about far detection for iron really makes me think of coil arrangement,(nulling) where at greater distance you would have (for example)a decrease in amplitude, but at closer distance it would rise again,(after passing by a minimum) and then be ignored.

I should be able to find almost all components for my PCB, but i have been working on other project (flight per view w/GPS and OSD to build an UAV ) and repairing my boat engine that failed
regards,
Fred.