Any Classic II homemade VDI's out there??

[scott-bc]

I have modified my classic II as far as it can go. What I would like to have on it is a simple LCD visual ID attached to it. I was thinking is it possible to measure the incomming frequency from the coil with a high impedance freq LCD meter? It is my understanding that the frequency coming out of the coil is changed by the target in the ground and measured by the recieving coil. Could not a person measure this returning frequency to decifer what target it is? I was told someone did this recently but took the signal from the coil. Iron will give one frequency signal and silver should give another. Is this possible??

Scott

[Carl-NC]

Targets are identified by their phase shifts, not frequency shifts. So what you need is a circuit that quantizes the RX phase shift and assigns an ID to each quantum. You can do this by modifying the Classic's circuitry, or you can create a separate TID circuit that runs independently, such as done with the Sunray meters for Sovereign detectors.

- Carl

[scott-bc]

Carl,

Thanks for the info. Does Sunray make a meter to do this? I can't seem to find it on the web? I know a guy who has an exlporer and he uses a patriot meter and it gives out a LCD reading and based on that it helps him to determine what is a good number to dig. You mention a circuit to measure this phase shift where do I get one? I think if there is a clamp on meter to do this that would be nice.

Thanks.

Scott

[Sean_Goddard]

I suspect he is using a Sovereign not an exploder, moot point but relevent none the less. The Sovereign has internal circuitry to give a DC voltage out depending on the CONDUCTIVITY of the target object. The Patriot is nothing more than a voltmeter, albeit a very clever and expensive one.

Whites use a "Flash Phase conversion" system on the Classic ID. If you go to http://v3.espacenet.com/textdoc?DB=E...=CA2243690&F=0 and look at this patent, it will tell you how they do it. Should be a simple add-on, but requires some knowledge of electronics.

I am in the process of designing a meter such as you have asked for, this will work with ANY single frequency machine. Hopefully it will be available early next year as a commercial item priced around $99 and is FULLY user programmable too.

[scott-bc]

Sean,

That sounds good. Let me know right away. Do you have any prototypes that would work now??? I don't need any fancy bells and whistles.

One year OMG thats a long time. By that time I will have a DFX!

Scott

[Qiaozhi]

Targets are identified by their phase shifts, not frequency shifts. So what you need is a circuit that quantizes the RX phase shift and assigns an ID to each quantum. You can do this by modifying the Classic's circuitry, or you can create a separate TID circuit that runs independently, such as done with the Sunray meters for Sovereign detectors.

- Carl

Here's an interesting Tesoro patent that describes how targets are identified by their phase shifts.
http://geotech.thunting.com/pages/me.../US4486713.pdf
Although adding a VDI-type display is somewhat more complicated than this, since the target-induced phase shift is not constant, but is also a function of the distance to the target.
In other words, it's easier to identify the target conductivity when it's close to the coil, but there's an element of guesswork when it's further away.

[Carl-NC]

The Sovereign has internal circuitry to give a DC voltage out depending on the CONDUCTIVITY of the target object. The Patriot is nothing more than a voltmeter, albeit a very clever and expensive one.

I did not know this. The Sunray meter I have is run strictly off the coil. Would it not have a full synchronous phase detector?

[scott-bc]

This weekend I had my unit apart and tried numerous places to get a voltage reading that varies from iron to silver. I had no luck and it seems that the circuitry switches whether it is ferrous, non-ferrous or all metal. What I tried to do is get some crude voltage on the board that would change depending on the object. I guess I will keep on trying.

[Unregistered]

ML meter

Hi Carl,

Sean is right. The ML and Sunray meters work by reading an internal 8 bit D to A voltage on pin 5 of the coil conector. These meters rob power from the TX signal using a full wave bridge connected accross pins 1 and 2. The receive signal passes through uneffected. The calibration knob is used to zero out any offset differences in the coil preamp. Just a voltmeter without a battery.
Something I keep hearing on the forums, Soverign, Explorer and Excalibors are "multi-frequency". They are actually time domain and operate very much like a bipolar pulse circuit. The demodulators sample, beginning, middle and ends of the short and long period pulses. Then adds and subtract, etc, to derive ground balanced low, high conductive and ferrous signals. The guys in marketing are telling the truth about the 17 harmonic frequencies but what they don't tell these are ignored by the detector. See the patents its all there. Thanks for the great forum - Mark in Florida