Do you think a headphone limiter switch could be used as a surface blanker?

I have a use for surface blanking. In thinking about how to obain it, I started thinking about doing it in headphones. Possibly using a limiter switch, or maybe replacing a limiter switch with a pot that would let me dial in the limiter audio level. Haven't thought it all the way through yet, but wondering if it is possible.

Actually I was thinking of asking Skiwiz to build me a set of phones with it, if it could be done.

HH
Mike

How this would work depends on the audio signal coming from the detector. Machines like the Tek T2 use pulse-width modulation to create different volume levels. So the 'raw' volume level is always 100%, and level-based blanking methods won't work.

Thanks Pimento.

How would you do it?

Mike

Get a Blissool V6. You'll have some blanking capability and real good depth as well. Plus it seems the detector's platform along with its coils when in iron act more like a Deus/Makro Racer, not like a T-2 or F75.

Good recovery speed available on the V6 as well.

Just my 2cents worth.



Edited 1 time(s). Last edit at 11/20/2015 06:48PM by tnsharpshooter.

How would I do it? Tough question, honest answer is 'I wouldn't do it', I can't see how it would work at all. It seems a bizzarre idea. I detect hearing everything, the idea of muting something based on whether it's 'strong' or not sounds like a good way to miss lots of targets to me. What happens when your first hit of a target is when it's just in front of the nose of the coil, and it gives a weak response? Then you investigate, sweep over the area again, get a better signal, and it magically disappears?
And as for building it into headphones, well that's not the ideal place to do it, inside the detector, probably before the audio amplifier would be more obvious. But I guess you're wanting this to work on a machine that internal tinkering is not viable.
You're going to need a dummy load to simulate the earphones, something like 20 ohms -> 100 ohms. The voltage on this would be fed to an audio amplifier, preferably one with a mute function integral to it, but it's not too hard to add a mute function seperately. Monitor the voltage across your dummy load, using a comparator, see if it exceeds your threshold for a 'shallow target', then activate a mute switch fitted before the amplifier.
You could power all this from a single lithium polymer rechargeable cell, I should think.

Mike you could TRY this maybe with some sort of outcome of success but really dont know..

I could see it maybe working for a VCO audio report..

MAYBE

[www.amazon.com]

try and figure out when the objects start to get squeally(sp) ...Coin sizes that is an maybe the EQ can be set to blank that HZ??

Not sure..

the way they work on Detectros in the circuit is I believe like a Big Bud pro it is the running depth meter is simply linked to the the audio jack...say when switch is on a setting of 4 anything below a reading of 4 inches depth will mute... when the meter shows say 2 inches no report is heard as the audio jack is clipped off anyything above 4 like say 6 inches it is not clipped ..

it would be easy in an analog circuit but in a digital circuit or even a circuit with no running depth meter its tuff..

If one spent time studying a circuit they may be able to add a blanker to a machine like a G2 or omega ..you could tap off the bar graph to trigger a speaker connect/ disconnect........... when a certian amount of lights are lit on the continuous running depth meter it would close the circuit to the speaker thus reporting as usual.... when a few are not lit it would open the circuit to the speaker thus blanking...

Just thinking out loud..LOL!!

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla



Edited 2 time(s). Last edit at 11/20/2015 08:28PM by Keith Southern.

"Crazy idea!
Most of my gold has come from just intertwined in surface grasses to a few inches!"

A possibly simpler solution:
Have a dummy load that's exactly the same resistance as the earphones. And arrange your blanker to switch between earphone and dummy load. That way, the load on the detector's output is unchanged, so the voltage generated on the load is also unchanged. You will have to monitor the voltage level the same way as previously mentioned, and have it switch one load in, the other out, as appropriate. Then no amplifier is needed.

Mike Hillis Wrote:
-------------------------------------------------------
> I have a use for surface blanking. In thinking
> about how to obain it, I started thinking about
> doing it in headphones. Possibly using a limiter
> switch, or maybe replacing a limiter switch with a
> pot that would let me dial in the limiter audio
> level. Haven't thought it all the way through
> yet, but wondering if it is possible.
>
> Actually I was thinking of asking Skiwiz to build
> me a set of phones with it, if it could be done.
>
> HH
> Mike
I would be happy to do it for you Mike if I could but I honestly do not know anything about building a limiter circuit.

Get a GTI 2500 and = problem solved

This is a feature I have been asking for on the 3030 and it is easy to do via update. It would be a simple logic statement.

Example:
IF signal strength(depth) is greater than 4(inches) than audio report.

I would not hunt that way it's up to you to dig or not dig but I want to hear everything even iron

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

[www.youtube.com]

If you don’t dig it, then how are you going to know what you’re missing!
How can you have your pudding if you don’t eat your meat!

Mike

I feel the only true way would be with an advanced discrimination, some of the older models I had this worked great!

Treasure Baron, Mark 1, and either Blisstool V5 or V6 can be set to blanket out all signals down to 3", 4", 5" or even 6" inches depending on setting.

Using the audio I feel would not be dependable, at least I feel it wouldn't be? Could be wrong, been wrong before.

Paul

Des D Wrote:
-------------------------------------------------------
> "Crazy idea!
> Most of my gold has come from just intertwined in
> surface grasses to a few inches!

Same here as rings have a tendency to have root grow through and keep them suspended.
Coins just slide right on down,and in Florida until they hit something like a root,rock,clay or hardpan.
Other than the beach rings and chains are usually very shallow.

------------"Cz's still bad to the bone".------------
Living on a big ass Astroid.
The woman that got my rib,I want it back.

Thanks to everyone that responded. I think I'll chase two paths, Pimento's and Paul's.

While I'm chasing parts for a circuit, I'll also look at detectors that offer/offered surface blanking. This is for very specialized and focused site work in extreme modern day trash. The squeal of the trash in this type of site ruins my hearing to the softer signals below it. I need to remove it.

So looking at the list of units that offer/offered surface blanking, I see the beginning of a list....

GTi2500,
Treasure Baron,
Mark 1,
Blisstool V5,
Blisstool V6,
Time Ranger,

any others?

Thanks
Mike

Good Luck, Mike.



Edited 3 time(s). Last edit at 11/25/2015 08:19AM by Pimento.