Lrl from Italy

[Napsterce]

Thank you Franco, you're the best.

[dream_man]

Here I attached a new PCB of the 8MHz - Quartz LRL Sensor Stage + Power Stage with Low Battery Indicator + Display Stage (3 LEDs), and its schematic. Hope it helps you my friends.

[pigeon]

Originally Posted by dream_man

Here I attached a new PCB of the 8MHz - Quartz LRL Sensor Stage + Power Stage with Low Battery Indicator + Display Stage (3 LEDs), and its schematic. Hope it helps you my friends.

thank you very much my dear friend

[FrancoItaly]

Hi dream man,
very good work, in this way my LRL looks really professional, although I use simulation programs, for PCBs and for schemes still use hand.

Regards

[pigeon]

Originally Posted by FrancoItaly

Hi dream man,
very good work, in this way my LRL looks really professional, although I use simulation programs, for PCBs and for schemes still use hand.

Regards

[dream_man]

Originally Posted by FrancoItaly

Hi dream man,
very good work, in this way my LRL looks really professional, although I use simulation programs, for PCBs and for schemes still use hand.

Regards

Thank you dear Franco. Actually I tried to copy the sensor stage exactly from your "PcbCpmp.PDF" file.

[Golden]

This LRL detects the target in front ..or sideways? How high is more sensitive?
Thank you .

[dream_man]

Hello dear Franco;
1. May I know what will happen if I decrease the amount of C17 and C18 from 100nF to 33nF?
2. Can we use Darlington NPN transistors like BC517 or MPSA13 ?
Thank you.

[FrancoItaly]

Hi dream man,
1. C17 and C18 are not critical, with R15 and R16 constituite a low pass filter to eliminate the residual signal to 8MHz. This filter may be necessary if the sensor stage is far from the rest of the circuit (a few tens of cm, as in my case).

2. In my opinion darlingtone transistors have too much gain and there would be the risk of self oscillations.

Best Regards

[dream_man]

Thank you dear Franco

[Hadi]

Hello Franco,

I replaced 100nF with 33nF and I tested it with cellphone and ion that was sensitive of before. Also I used BC517 instead of 183 or other I hadn't any problem in my circuit.
On collector of TR4 I have 2.5 volts and on out that's about 0.26 V.
The reason of I can to detect mv is ADC of uC. I used ATmega328.

In your circuit when we have more train pulses in antenna will be more voltage in out.
We get pulses not frequency so when the frequency of antenna goes to high the pick up signals goes to faster and better.

Dear Franco do you accept to change local oscillator with high frequency crystal such as 28MHz.

B.R

[FrancoItaly]

Hi Hadi,
If when you touch the antenna the DC signal (0.26V) decreases I think that's ok, but remember that if at TR2 base we have for example 1 mV (at 8 Mhz) and the DC output is 5.2V for a given sensor stage and in your sensor stage you have also 1 mv at input and 0.26 at output, this means that your sensor stage has a 20 times lower gain (0.26 X 20 = 5.2).
I use sometimes Arduino that has the same micro-controllor and the ADC is 10 bit, that's 5 mV resolution, this means that a variation of less than 5mV is not perceived.
My lrl works in the range 3-10Mhz without changing any value but I don't know with other higher frequencies, definitely not work with lower frequencies. I think that there is an optimal ratio between frequencies of antenna and internal oscillator.

Best Regards

[UltraLRL]

Originally Posted by FrancoItaly

I use sometimes Arduino that has the same micro-controllor and the ADC is 10 bit, that's 5 mV resolution, this means that a variation of less than 5mV is not perceived.

Best Regards

it's for 5v as reference voltage and 10 bit ADC (2 ^10 = 1024)

ADC resolution = Vref / 1024

for Vref=5v resolution is about 5 mv
for Vref=2.56v resolution is about 2.5 mv


for higher resolution,lower Ref Voltage is Recommended

[FrancoItaly]

You are right, but do not know if it's worth to use a micro controller, I think 3 LEDs are sufficient.

[Golden]

Hello Franco,
How detect this LRL the target : front or.. sideways ?
Thank you.

[mustefa ubram]

Franco, for a maximum voltage of 5 V output must be changed?
Is it possible to reduce the output voltage with op-amps

[Napsterce]

Hello Franco, the lrl is complete. Plastic box, antenna used from another device, wooden handle and the battery is external with 12.47 volts power from it. I have tested it and it reacts with the north, i dont get other signals, only that. What should i do to stabilize the compass effect? Thank you.

[FrancoItaly]

for Golden: the lrl detects front and sideways.

for mustefa: if you use a device that works at 5V you must reduce the output voltage of sensor stage (that may be also 8V or greater with a big target). Yes you may use an operational or a 5V zener diode and set the output voltage of sensor stage at about 4V.

For Napsterce: all the lrl works with a 12V stabilzed power. The only way to reduce the compass effect is to reduce the gain.

Best Regards

[mustefa ubram]

Originally Posted by FrancoItaly

f
for mustefa: if you use a device that works at 5V you must reduce the output voltage of sensor stage (that may be also 8V or greater with a big target). Yes you may use an operational or a 5V zener diode and set the output voltage of sensor stage at about 4V.


Best Regards

thank you franco
How much output voltage sensor stage for standby?(When there is no target)

Which is part output is better? for connection to the Microcontroller?out put sensor stage?

[Napsterce]

Dear Franco, i have test field with cooper, will it give results, is it working with cooper or only gold?

[FrancoItaly]

Hi mustefa,
6V for me is the better value for standby, the output of sensor stage is the only output for other devices, Microcontroller or operationals.

Best Regards

[FrancoItaly]

Hi Napsterce,
I have no experience with all metals, but surely Lrl detects gold, silver and brass for my direct experience. More time the metal is buried, more strong is the phenomenon.

Best regards

[Napsterce]

Wikipedia: Brass is a metal alloy made of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties;

Franco, according to this it is going to detect copper, we will know after a month or two. Thank you.

[dream_man]

Hello dear Franco ;
There are several capacitors like 100nF and one 33nF and so on. Which type of capacitors are better on your LRL? I mean ceramic disk, multi layer, polyester, or MKT ?
thanks for responding.

[FrancoItaly]

Because we are in the radio frequency bandwidth (8MHz) the better choice are the ceramic disk.