Lrl from Italy

[LRLMAN]

POWER-DISPLAY STAGE

Hello dear friends I have a small obstacle to put to work my LRL I only need to complete the stage of Power-Display, I develop a PCB but this I did not work because the potentiometer 20k I put the device began to heat up and smelled burned and decided to review all the PCB but nothing; Now draw another PCB through the program called: Live Wire and PCBWizar and the program suits me the tracks as follows but I have the impression that even is not complete the PCB and I think that some lines should go to negative part and I would like to know if someone in the forum here can help me to complete the Power-Display Stage and can test it on field.

Regards.

LRLMAN.

[FrancoItaly]

Try to feed the part relating to IC2 (the stage display) with a stabilized power supply, obviously with 12V, excluding all the part related to 78l12 and IC1. With led off the absorption will be a few mA, if it is not so you have to check that there is no short circuit between the + 12V and ground. Leaving the power section disconnected connects the stabilized power supply instead of batteries and if the absorption is very high you have to control C1 and C3, sometimes it happens that the electrolytic capacitors are defective, otherwise it can also be a short circuit here between + 12V and ground.

[LRLMAN]

Try to feed the part relating to IC2 (the stage display) with a stabilized power supply, obviously with 12V, excluding all the part related to 78l12 and IC1. With led off the absorption will be a few mA, if it is not so you have to check that there is no short circuit between the + 12V and ground. Leaving the power section disconnected connects the stabilized power supply instead of batteries and if the absorption is very high you have to control C1 and C3, sometimes it happens that the electrolytic capacitors are defective, otherwise it can also be a short circuit here between + 12V and ground.

Ok thanks Dear Franco, but then... how do I know which are the tracks that are missing for the pbc is properly ?? and can work well? could you help me a little ?? please.

Thank you so much for your help Franco.

receive a big hug.

Lrlman.

[abdou2014]

Is it necessary MR Franco to make two power supply. One for sensor and one for display stage. And separate them. Because I have supplied both with a single supply ?

[abdou2014]

Here is my PCB 8 Mhz

[FrancoItaly]

No, there is only one power, 12V, that goes to sensor stage and to display stage. The only way to test PCB is to follow every track and make sure it complies with the wiring diagram.

[Hadi]

Hi Franco,
I have an idea. Can we use A/D uc and LCD display instead of display stage. That can to detect low signal from sensor stage.

[FrancoItaly]

It's a good idea, I built two lrls with 10 LEDs, for one I used a LM3914 and for the other I used a PIC16F88 but I think that the LM3914 it's the best choice. With 1 LED version you must connect the IC3A output to LM3914 input and change the inputs, that's output of sensor stage to non inverting input of IC3A and the cursor of P2 to R10. However, even the version with 3 LEDs works well, although less accurate.

[Hadi]

Thank you so much Franco.
I will try to reach best result and I'll send you hex file.
By the way how much the max voltage is in output of sensor stage? (I mean when 3 LED's are on)

[FrancoItaly]

The max voltage (theoretical) at output sensor stage it's about 8V. If without target signal the output is (for example) 4V we may suppose with a very large signal an output of 5V, that's 1V range, this range is amplified by the first operazional. If we suppose a gain of 6 the range at operational output it's (for example) 2 - 8V or 0 -6V.

[Hadi]

Thanks for your kindly guide.

[abdou2014]

is it more easy to get the center of target with your lrl than the vlf receiver lrl ?

[FrancoItaly]

I don't know the vlf/lrl, but in general the lrls are not able to make a pinpoint of the target as the VLF metal detectors, but the signal increases approaching the target and disappears completely right above the target.

[abdou2014]

is there a trick to determining target location. at what distance from target the signal disappears ? and is it necessary to be facing south direction ?

[abdou2014]

Franco LRL with True RMS