Lrl from Italy - Page 124

Zicos · #**3076** 10-13-2023, 10:22 AM

what is the mistake i am doing?

Zicos · #**3077** 10-13-2023, 10:50 AM

the calibration should be done with:"1"(piece of copper wire or with telescopic antenna,?)and the result should be 0volt without crystal,"2"(the length should be 30-40cm, not less or bigger?)

FrancoItaly · #**3078** 10-13-2023, 02:17 PM

For convenience, the calibration is done with a piece of wire instead of the antenna, but it could also be done with the antenna as long as it is placed about 10 cm from L1. The length of the antenna, during calibration, is 40 cm, but you can vary it and see the result. Honestly, I've never measured the piece of wire, I use a connector with two crocodiles and I measured it now, it's 40cm.
These values are indicative, unfortunately the sensor stage is very critical and it is important to obtain maximum gain because the "phenomenon" has a very small amplitude.

Zicos · #**3079** 10-13-2023, 02:28 PM

thank you very much..will try it and let you know.

Zicos · #**3080** 10-14-2023, 06:00 AM

good morning Mr. Franco. and to the children of the forum. so I tried it as I calibrated it with the antenna open 97 cm and without a crystal 0 volts. and with a crystal 5.04 volts. it did not catch the signal in the garden.. is there any chance that the display is to blame??? (3led p1 22k -p2 500k -p3 10k)

Zicos · #**3081** 10-14-2023, 06:13 AM

how can i upload photos????

FrancoItaly · #**3082** 10-14-2023, 09:06 AM

Quote:

Originally Posted by Zicos

how can i upload photos????

Select " Attachmens "

Zicos · #**3083** 10-14-2023, 11:30 AM

where is Attachments?

FrancoItaly · #**3084** 10-14-2023, 01:59 PM

On the page where you write your post, at the top, in the center, next to the Smiles.

Zicos · #**3085** 10-14-2023, 08:27 PM

this piece of copper wire is used by you Mr. Franco to calibrate???

Zicos · #**3086** 10-14-2023, 08:43 PM

I also calibrated with this copper wire that you see in the photo and I understood that the volts go to 0 without a crystal as soon as you turn it in another direction it gets volts again. how should I calibrate??? I think the translation doesn't let me understand what do you want to tell me..

FrancoItaly · #**3087** 10-15-2023, 09:47 AM

Quote:

Originally Posted by Zicos

I also calibrated with this copper wire that you see in the photo and I understood that the volts go to 0 without a crystal as soon as you turn it in another direction it gets volts again. how should I calibrate??? I think the translation doesn't let me understand what do you want to tell me..

Inside houses there are many RF signals, the sensor stage with an antenna at the input can definitely detect these signals. The only thing different from you is that you use a rigid piece of copper while I use a flexible wire and that you move the antenna to different positions. Leave the wire in the same position and touch it only to check if the signal decreases (once the oscillator is connected).

Zicos · #**3088** 10-15-2023, 01:53 PM

hello mr franco.thank you very much for helping me. i found the problem. for power supply use a 13.5 volt power supply and then i connect a step down for 12 volt. as soon as I put the power supply with 13.5 volts without the step down the problem was solved.. in the garden test and in the field I used a 18650 battery with a step up to have 12 volts. that must be the problem.. but the signal in the garden was very good and clear... as i had it before but in the field nothing is heard. i will do the circuit with the 78012 and see what happens... again thanks a lot.

FrancoItaly · #**3089** 10-15-2023, 02:23 PM

The 7812 IC needs at least 15V input to stabilize correctly, otherwise a low drop IC can be used. I use two 9V batteries in series so that the absorption of all the LRL is around tens of milliamps.

Zicos · #**3090** 10-15-2023, 05:34 PM

the 9 volt batteries should be simple or do the rechargeable 9 volt ones as well?????

FrancoItaly · #**3091** 10-16-2023, 09:10 AM

Quote:

Originally Posted by Zicos

the 9 volt batteries should be simple or do the rechargeable 9 volt ones as well?????

I use rechargeable batteries and normal ones as a spare. In terms of performance there is no difference.

Zicos · #**3092** 10-20-2023, 07:14 PM

good evening Mr. Franco.and to everyone. i made the 7812 circuit .. but i used 5 batteries (18650). because i had her.the sensor now has c9(680pf),c13(680pf),c14(680pf) and c2(2 capacitors in series (2.2pf)....output voltage without crystal is 0v with copper antenna. .....and with 40 cm flexible cable again 0 volts and when the antenna turns the output voltage is again 0 volts. the output voltage with crystal is 5.49 volts when I touch the antenna the voltage does not change it stays the same. in the garden test it catches the signal it was getting from a longer distance. but close to the house it is getting other signals I don't know for sure it is getting it... when I can I will also go to the field to test and let you know what it did..

FrancoItaly · #**3093** 10-21-2023, 09:12 AM

there should be a decrease in the signal when touching the antenna, even a small one, otherwise it could be a self oscillation. What transistors did you use?

Zicos · #**3094** 10-21-2023, 10:26 AM

i used bc547c

Zicos · #**3095** 10-21-2023, 10:33 AM

when I put it in the box and connect the antenna amplifier and did the test in the garden when I touch the antenna the first led lights up and the buzzer sounds. when I calibrated it it showed no change in output voltage.

FrancoItaly · #**3096** 10-21-2023, 02:04 PM

The important thing is that there is a variation when touching the antenna, normally it is a decrease. Obviously it is important that it works in the field.

Milad.salsa · #**3097** 10-23-2023, 06:26 PM

Quote:

Originally Posted by FrancoItaly

The important thing is that there is a variation when touching the antenna, normally it is a decrease. Obviously it is important that it works in the field.

Hello Mr. Franco When we want to measure the self-oscillation of the circuit, we remove the crystal from the circuit and adjust the potentiometers p3 and p2. Should the antenna be connected or disconnected?

Zicos · #**3098** 10-24-2023, 07:55 AM

hello mr franco... i went to the field but the machine was not catching the target. when adjusting the sensitivity with which pontesiometro do you do it????? the sky and ground effect was there..the compass effect was not. unless I increase the sensitivity more.. how to adjust it?????

Zicos · #**3099** 10-24-2023, 08:18 AM

when calibrating with crystal and antenna when i touch the antenna the output voltage does not drop or rise... when i put the antenna amplifier the output voltage goes up.... only if there is auto oscillation in the circuit the output voltage goes down when i touch the antenna without amplifier but also with antenna amplifier... without oscillation how can i achieve reduction of the sensor output voltage when i touch the antenna??????? should there be a change in sensor output voltage when touching the antenna to detect the metal effect?? or does it work like this??? is one of the components at fault????? the prices of the parts are always the same used or do they change sometimes?????what do you think????? sorry for so many questions..

Zicos · #**3100** 10-24-2023, 08:36 AM

i made another sensor to see what happens... and it has the same problem. when i touch the antenna the output voltage does not drop or rise it is stable... i use BC548c.. i used that antenna i have and the sensor output voltage is always 0volt without crystal.. with crystal it is 5.44volt with only one capacitor c2(1pf) .if i remove c2 the output voltage is 4v if i remember correctly... that way the output voltage drops when i touch the antenna..