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  #1576  
Old 04-06-2017, 04:16 AM
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My minelab sucked ionic field from the testing site.It may take another year to ionic field back
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  #1577  
Old 04-06-2017, 07:14 AM
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Quote:
Originally Posted by folharin View Post
My minelab sucked ionic field from the testing site.It may take another year to ionic field back
Yes, minelab sucking.
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  #1578  
Old 04-14-2017, 09:46 AM
abdou2014 abdou2014 is offline
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Thank you Mr Franco for your beautiful LRL finally I succeeded, I have a friend who had a small problem, when he adjusts the sensitivity with the gain, Each time the gain decreases alone and it will be forced to recalibrate it by Increasing the gain, The power supply is stable LM7812.
What he should do ?
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  #1579  
Old 04-14-2017, 10:25 AM
FrancoItaly FrancoItaly is offline
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I'm happy for the good results, can you tell us which target and at what distance is it revealed? About your friend, the DC output of the stage sensor is stable? In DC amplifier (LM35 what values for R4, R3 and C1? With too much gain stage may self oscillate. The battery power is more than 15V? However, it is normal that changing the gain also needs to adjust the threshold.

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  #1580  
Old 04-14-2017, 11:16 AM
abdou2014 abdou2014 is offline
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About 3 meters from test field , About my friend R3, R4 and C1 as the schematic, Two battery 9V that is to say 18v Connect with LM7812, he told the gain decreases alone and slowly, exp : If it sets the gain potentiometer to a point where the led flashes, after a few seconds the led turns off , and the sensitivity decrease ???
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  #1581  
Old 04-14-2017, 11:30 AM
FrancoItaly FrancoItaly is offline
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As I said you have to check the output of the stage sensor, the DC voltage must be very stable. Another cause can be the influence of the human body, moving the hand away after making the adjustments can cause a decrease in the signal.

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  #1582  
Old 04-14-2017, 08:08 PM
abdou2014 abdou2014 is offline
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you was right, the DC output of the sensor stage isn't stable, What is the source of this disturbance ? What must he change ?
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  #1583  
Old 04-15-2017, 10:36 AM
FrancoItaly FrancoItaly is offline
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Probably the stage sensor is oscillating, there is too much amplification or the defect is in the PCB. You must repeat the tuning process.
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  #1584  
Old 04-17-2017, 10:28 PM
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zakari zakari is offline
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hi franco
how are you

I don't have any self oscillation at the sensor stage

but i have self oscillation at the display stage

how can i reduce self oscillation in the display stage

R3,R4,C1 are schematic value

thank you very much


best regard
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  #1585  
Old 04-18-2017, 10:14 AM
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zakari zakari is offline
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hi
I have made some many pcb

I don't have any problem for revealed the metal this lrl work absolutely

MY problem is stability of this device

some of the pcb increase and some of them decrease voltage of the ledes

all of this pcb not have self ocsilation at the sensor stage without the xtal

when the devise is stable that revealed the baried metal very easy


thank you very much mr franco for your lrl
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  #1586  
Old 04-18-2017, 10:17 AM
FrancoItaly FrancoItaly is offline
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Disconnects the output of the sensor stage and checks if there are still oscillations.
If so, increases from 22nF to 100nF the capacitor between the output and the input- of the first operational (DC amplifier) and set the potentiometer to the minimum gain.
To minimize the possibility of auto oscillations, it is advisable to use two pcb one for sensor stage and the other for display stage, plus the sensor stage pcb is better double face, with lower face connected to ground. If there are no oscillations it's possible that there is too much gain in sensor stage, In this case decrease C13 / C14 and increase C2 / C3 / C4 for to have a DC output in the range 4-6V.

Best Regards
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  #1587  
Old 04-18-2017, 10:30 AM
FrancoItaly FrancoItaly is offline
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You can also try to change the quartz frequency for example 6 or 4Mhz. It seems strange that the DC amplifier may oscillate as there is not much gain.

Best Regards
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  #1588  
Old 04-18-2017, 06:00 PM
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zakari zakari is offline
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hi franco

thank you so much

best rgards
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  #1589  
Old 04-27-2017, 04:10 PM
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zakari zakari is offline
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hi dear franco

one of the my friend ask two question
and he want your respond about that

1-when does the led turn off? while the antenna is above the target or operator's feet is above the target

2-what's the difference reaction of the lrl when that sense the sky or compass effect and when that sense the barried metal


thank you so much

best regard
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  #1590  
Old 04-28-2017, 09:58 AM
FrancoItaly FrancoItaly is offline
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The behavior is normal for a lrl, near and on the target's vertical, the signal disappears. Instead, with the compass effect, the signal remains practically constant moving in the north / south direction or vice versa. However, the lrl must be set to not have this effect (decreasing the gain).
I would like to know the type of buried metal and the distance of revelation, thank you.

Best Regards
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