complete project

[Aziz]

Hi Aziz, I can see what your talking about.
Mick

Excellent Mick.

You can put a gold ring nearby the iron plate in the "iron orientation response". This should show the "target masking effect". It is similar to a hot iron mineralized ground, masking out the target.

If you can show some CRO pics, others could see it too.

Cheers,
Aziz

[6666]

Thanks pelanj, 16F690 is ok, there are tons on fleabay
cheers

[Midas]

The general idea is to keep all noisy parts together and away from the analog, where the noise is really not desired.

On the above circuit I have decoupled the audio transistor and added the capacitors to keep the hard switching square wave noise out of the supply.
In fact, I see no reason why the whole audio should not be on the TX board.

Tinkerer

I'd like to discuss this a little bit more because there is a lot of different factors to consider:

1. PIC on RX board near front end amplifiers - bad
2. PIC on TX board near coil inputs - also bad
3. PIC on TX board with ADC input far from final stage amplifier output on RX board- bad, maybe not as bad

Is the TX board the right place for the PIC once it starts performing late stage signal processing? In this configuration it has two negative qualities but maybe being away from the front end amplifiers makes it worth it ? Maybe on the RX board is better, who knows ? Not me...

Midas

[Aziz]

Reminder:

Anyone made the measurements, I have raised recently?
It would be very interesting to show the effect.

Single freedom of parameter (a simple threshold) isn't enough to GB or to discriminate.
Aziz

[Tinkerer]

Reminder:

Anyone made the measurements, I have raised recently?
It would be very interesting to show the effect.

Single freedom of parameter (a simple threshold) isn't enough to GB or to discriminate.
Aziz

I am not sure what you want to demonstrate with the test you propose. But here is some data that is pointing more or less in the direction you indicate.

The response is different for different targets.

Now, there are many possible differences with in targets. Actually millions of variations. If We want to differentiate the targets, we need to start somewhere. We could start by dividing the different responses into a few categories and then classify the targets within these categories.

One way is to take many samples along the RX signal wave form and look for differences in the response at the different sample times.

The more different samples we take, the more information about the target we can gather.

Here is a small example:

Taking 4 samples at different times, with a target of gold, FE or iron, and a ceramic magnet. The ceramic magnet was actually used for the purpose of representing the Earth magnetic field.

Sample 1, gold down, FE up, magnet down. Representing in binary 0 1 0
Sample 2, gold up, FE down, magnet down. 1 0 0
Sample 3, gold up, FE down, magnet down. 1 0 0
Sample 4, gold down, FE up, magnet down. 0 1 0

We see that we could add sample 1 to sample 4 and get more gold signal amplitude, but still have the EF response within the total response.

If we invert one sample and subtract, we get a different result. What I mean to say, is that using a mathematical formula, we can manipulate the result, to discard the part that we do not want or enhance the part that we want.

This does not take into account the size of the target that would be represented by signal amplitude, nor does it take into account the conductivity of the target, that would be represented by the TC of response decay.

Each one of these characteristics changes the signal amplitude at a certain spot along the wave form.

The same happens with the ground response, which is just a large target with specific characteristics.

So let's say we take 10 samples along the RX signal wave form. The time of each sample is chosen to give the most information about one specific aspect. We will then end up with a lot of numbers to manipulate.

We can further enhance or attenuate the response of each sample by manipulating the sample width.

Tinkerer

[6666]

Tinkerer your schematic seems to list the pic as being a PIC16F690-x-p
is that some generic label ?
I can get PIC16F690-I/P will that work ?
and do you have any pictures of your coil ?
thanks
6666

[Tinkerer]

Tinkerer your schematic seems to list the pic as being a PIC16F690-x-p
is that some generic label ?
I can get PIC16F690-I/P will that work ?
and do you have any pictures of your coil ?
thanks
6666

I just took the symbol from the DESIGNSPARK software, was not even aware of different types. The common variety works just fine.

Tinkerer

[6666]

Thanks have ordered PIC16F690-I/P will see what happens
cheers
6666

[6666]

Here's a plus, pickit2 says programming successfull,will test and see what I get out of the pic.

[6666]

The the tx output wave form from pin 13, is at the top of screen,
the bottom waveform is sample 1.

Gotta clean the dust off the CRO one day

[Tinkerer]

The the tx output wave form from pin 13, is at the top of screen,
the bottom waveform is sample 1.

Gotta clean the dust off the CRO one day

Looks OK, now show us the Flyback and the RX signal. You are doing great.

Tinkerer

[Aziz]

Hi all,

anyone made the measurements, I have raised recently?
Please show the CRO pictures...
The crucial point must be shown here...
Aziz

[Midas]

Hi all,

anyone made the measurements, I have raised recently?
Please show the CRO pictures...
The crucial point must be shown here...
Aziz

I think we get it Aziz, ground effects and target effects may be difficult to separate with only two samples. But none the less I think doing some field testing with it in its current form is still valid. Targets could still well sound different than variations in ground or even hot rocks. For example variations in ground probably won't have edges as well defined as valid targets. Hot rocks will probably have a wider area of detection to total amplitude ratio (seems logical to me.. any other opinions?). Whether all the subtleties can be detected by the operator needs to be determined. As Tinkerer has already pointed out the quality of the audio could make or break it.

Of course I'm not saying that more samples wouldn't make it a lot easier...

Midas

[Tinkerer]

I think we get it Aziz, ground effects and target effects may be difficult to separate with only two samples. But none the less I think doing some field testing with it in its current form is still valid. Targets could still well sound different than variations in ground or even hot rocks. For example variations in ground probably won't have edges as well defined as valid targets. Hot rocks will probably have a wider area of detection to total amplitude ratio (seems logical to me.. any other opinions?). Whether all the subtleties can be detected by the operator needs to be determined. As Tinkerer has already pointed out the quality of the audio could make or break it.

Of course I'm not saying that more samples wouldn't make it a lot easier...

Midas

When we look at the full RX signal wave form, we can find a dead spot somewhere along the wave form, for every kind of target.

I call this dead spot, THE PIVOT.

Time past, I posted many pictures showing THE PIVOT. If we take many samples, one of these samples will automatically fall on THE PIVOT.
Or we can guess, or make a look-up table with some known PIVOT times and chose this sample as the 0 level, to which we compare all other signal responses, resistive or reactive in nature.

The ground is nothing more than a complex large target. It has a well defined PIVOT. However, the changing ground will also change the spot in time (we are talking of the Time Domain here) so we need to locate the Ground PIVOT initially and then track this spot in time as it changes.

Using this Ground PIVOT as our 0 level, purely resistive targets will be 180 degrees phase from purely reactive target like ferrite.

Purely reactive targets do not exist in nature.

When we have a target that has both characteristics, like iron, the phase difference is different from 180 degrees.

The phase is what produces the PIVOT in Time Domain. The PIVOT is the spot in time, where the signal crosses the 0 level.

The PIVOT can easily be observed at the output of the preamp of the TINKERER RX.

If we can see it on the oscilloscope, we know it exists.

If we know it exists, we should be able to transform what we see into what we hear.

Since we are looking at small variations in the wave form, we need to make an audio that allows us to recognize small variations in the audio.

Hence, a good audio is needed.

Tinkerer

[mahd313]

hi tinkerer
please attach pictures of your coil ? (non_motion)
please information big coil for (non_motion )
thanks