Lrl from Italy

[FrancoItaly]

Thank's mr franco
But in this way ( parallel to the ground and then adjusting the threshold)when I move the antenna to left and right or downward or upward the LED be ON.Does my lrl work normal and correct or not?
Thank's

If there is not a target Led must be off, if LED is on there is compass effect and/or sky effect, then the gain is too much.

[payam20]

hi franco
after more than 2 year working on your lrl !! i found some thing weird !

i have increased gain (now i am using 4.7n for c13 & c14 ) without self oscillating .(but with a little change )
but no way to increase range from 15 meter i have reached this range with half gain! (15m from north to south and south to north half of range . other directions too weak !) and it senses some places without any metals some times !

antenna length 83cm . sensor voltage around 3.5 volt(decrease it from 3.5 volt will be too hard to work with ! it will be too noisy and increasing it will decrease range .

test for a copper bowl in around 80 cm for more than 5 years buried . (almost same result in real test )

[toorani]

hi dear franco
I put lrl in the box,In terms of conductivity, grand circuit and box is connected to the antenna,Is that right? I feel less sensitive.

http://uupload.ir/files/prks_photo_2018-03-09_11-24-16.jpg

now c1 is two Parallel Capacitor 560p and signal emiter tr1 is 2.4 volt pic to pic 8mhz and voltage out put(emiter tr5) is 4.5 volt but With Change c1 to 560p signal emiter tr1 is 3.5 volt pic to pic 8mhz and voltage out put(emiter tr5) is 5 volt,In your opinion,Which mode is better?
Thank you so much.

[toorani]

hi dear franco
I put lrl in the box,In terms of conductivity, grand circuit and box is connected to the antenna,Is that right? I feel less sensitive.

http://uupload.ir/files/prks_photo_2018-03-09_11-24-16.jpg

now c1 is two Parallel Capacitor 560p and signal emiter tr1 is 2.4 volt pic to pic 8mhz and voltage out put(emiter tr5) is 4.5 volt but With Change c1 to 560p signal emiter tr1 is 3.5 volt pic to pic 8mhz and voltage out put(emiter tr5) is 5 volt,In your opinion,Which mode is better?
Thank you so much.

also,now with Touch antenna,out put tr5 10mvolt Increases,Is that right?

[FrancoItaly]

hi dear franco
I put lrl in the box,In terms of conductivity, grand circuit and box is connected to the antenna,Is that right? I feel less sensitive.

http://uupload.ir/files/prks_photo_2018-03-09_11-24-16.jpg

now c1 is two Parallel Capacitor 560p and signal emiter tr1 is 2.4 volt pic to pic 8mhz and voltage out put(emiter tr5) is 4.5 volt but With Change c1 to 560p signal emiter tr1 is 3.5 volt pic to pic 8mhz and voltage out put(emiter tr5) is 5 volt,In your opinion,Which mode is better?
Thank you so much.

The shield must be connected to ground, the antenna must be connected only to C9/C10.
As regard to C1, there is no difference because the sensor stage gain does't change, but if the gain should be insufficient, C1 must be decreased, in this way the amplification of TR3 / TR4 can be increased. Another way is to decrease C2 / C3 / C4 (instead of C1). Keep in mind that the 8Mhz signal is only a carrier that is "modulated" by the phenomenon.

[toorani]

hi dear franco
now with Touch antenna,out put tr5 10mvolt Increases,Is that right?

with decrease c2/c3/c4 From 1.8p to 1p ,out put voltage Decreases(3.8 volt),Is that right?

with decrease c1 From 560p to 370p,out put voltage Increases(5.2 volt),Is that right?

also antenna through L1 connected to ground,as a result,The shield and antena Are connected,Is that right?

Thank you so much.

[FrancoItaly]

hi dear franco
now with Touch antenna,out put tr5 10mvolt Increases,Is that right?

with decrease c2/c3/c4 From 1.8p to 1p ,out put voltage Decreases(3.8 volt),Is that right?

with decrease c1 From 560p to 370p,out put voltage Increases(5.2 volt),Is that right?

also antenna through L1 connected to ground,as a result,The shield and antena Are connected,Is that right?

Thank you so much.

The important thing is that touching the antenna the signal at the output (TR5 emitter) changes, usually decreases.
The antenna is connected to ground through L1, therefore only to direct current, while for RF signals it must cross an impedance, so it is not true (and should not be) that shielding and antenna are connected together.

[afshin]

Thanks dear franco
When I adjust threshold then the led goes slowly to be on and l have to adjust threshold again.(there is not enough stability)while there is not self oscillation in circuit.(when I remove crystal the output voltage is 0 volt).what is that reason in your opinion?

[FrancoItaly]

Thanks dear franco
When I adjust threshold then the led goes slowly to be on and l have to adjust threshold again.(there is not enough stability)while there is not self oscillation in circuit.(when I remove crystal the output voltage is 0 volt).what is that reason in your opinion?

The body affects the threshold, bringing the hand closer to the lrl there may be a change in the threshold. If the DC output (TR5 emitter) is stable then everything is ok.

[afshin]

Very thanks mr franco
I measured TR5 emitter voltage, it goes slowly down and is not stable.
What is that reason mr franco?

[FrancoItaly]

Very thanks mr franco
I measured TR5 emitter voltage, it goes slowly down and is not stable.
What is that reason mr franco?

The proof of stability must be done outdoors, as there are too many sources of disturbance inside. If the fault persists there is probably a self-oscillation superimposed on the quartz oscillator. If you have made my double-sided PCB (one for the sensor stage), the self-oscillation can occur due to the excessive gain of TR3 / TR4. Change R10 and R12, from 1K to 1.5K and increase the total value of C1 / C2 / C3, put 1pF or more to have about 4-6V on the emitter of TR5.

[toorani]

hi dear franco
-I Detached the quartz ,votage out put is 0 and with Connected quartz ,voltage out put is 5v but with Touching antenna , voltage out put 10mv or 50mv Increases,In your opinion Why increases? and Is this important hess?

-Is the underlayer Must connected to pin - battry? and Is shild must connected to pin - battry?

http://s8.picofile.com/file/8319667300/photo_2018_02_19_20_32_40.jpg

Thank you so much

[FrancoItaly]

hi dear franco
-I Detached the quartz ,votage out put is 0 and with Connected quartz ,voltage out put is 5v but with Touching antenna , voltage out put 10mv or 50mv Increases,In your opinion Why increases? and Is this important hess?

-Is the underlayer Must connected to pin - battry? and Is shild must connected to pin - battry?

http://s8.picofile.com/file/8319667300/photo_2018_02_19_20_32_40.jpg

Thank you so much

When you touch the antenna output voltage must change, usually it decreases, but the important thing is that there is a change and this means that all the sensor stage is ok.
If there is not change it's possible that the stage is self oscillating or the stage works with overload (to much gain).

Pin - battery must be connected to sensor stage ground (upper side) and to shield (lower side of PCB)

[afshin]

Very thanks mr franco
And three questions:
1-Is it may that the ambient temperature affects the threshold stability?
2-what is the advantage of double side circuit comparatively to the one side?
3-what is the best voltage for output of the sensor stage?(TR5 emitter)

[toorani]

When you touch the antenna output voltage must change, usually it decreases, but the important thing is that there is a change and this means that all the sensor stage is ok.
If there is not change it's possible that the stage is self oscillating or the stage works with overload (to much gain).

Pin - battery must be connected to sensor stage ground (upper side) and to shield (lower side of PCB)

hi dear franco
Should the box shield be connected to the pin- battery too?