Lrl from Italy

[FrancoItaly]

Originally Posted by kaveh

Hello everyone and Mr. Franco. Mr. Franco, I am using a 14.7456 MHz crystal. How do I know what a good harmonic setting is for the c10 capacitor? When I turn the c10 trimmer, the output voltage of the sensor reaches its maximum in one place and the lowest in another. Where is the good harmonic?

It's ok when the output voltage of the sensor stage reaches its maximum.

[hoshi]

Hi dear friend Mr jeg
Your plan will not work properly

[Jeg]

Originally Posted by hoshi

Hi dear friend Mr jeg
Your plan will not work properly

Hi hoshi
What do you mean my friend? Its a simple differential amplifier.

https://www.electronics-tutorials.ws/opamp/opamp_5.html

[JHERICKU]

hello to all and to friend franco..I tried the 8mhz circuit display with 1led..Can u advice me if I got the correct output?when I turned on the potentiometer with the trimmer maximum I got 4 or 5.+ volts on resistor which connecting to sensor stage.When I connect the multimeter probe the beep and led goes off after I removed it the buzzer and keds on again...What do u think Franco?
Ps. The buzzer and led high and low when turning the potentiometer and trimmer..

[JHERICKU]

Originally Posted by Jeg

Hey Jh
Print the circuit and the board drawing and compare them to find out the components. If you have problems then put in a red circle what you need to know, and help will arrive.
ps. Why don't you use the other circuit with the trimmers?

I used it already Jeg..When I measured the output on resistor connecting on sensor stage,I got 4/5+.volts and the bezz and leds off..When I remove the test probe the buzz and leds goes on again..Do u think I got the correct output on display?
Ps..I used the display with 1 led..

[Jeg]

Hi Jh


Your voltage levels at sensor's output look that they are normal.
Assuming that your circuit is correct, then try the following.


When your voltmeter is connected alter your potentiometer to adjust again the buzzer/led threshold. Normally you will be able again to turn on your led.


Find a way to firm your meter's probes on the right points and then move your hands away to see if there is a variation on numbers. Then attach antenna with your hand and confirm that the output voltage drops down.



In general, device interacts with your body as it uses it to close the circuit between device and earth. Your hand acts as a capacitor plate. When you adjust your device your hand has to be firm and steady attaching the handle of your device or your aluminum box.


Regards

[JHERICKU]

Originally Posted by Jeg

Hi Jh


Your voltage levels at sensor's output look that they are normal.
Assuming that your circuit is correct, then try the following.


When your voltmeter is connected alter your potentiometer to adjust again the buzzer/led threshold. Normally you will be able again to turn on your led.


Find a way to firm your meter's probes on the right points and then move your hands away to see if there is a variation on numbers. Then attach antenna with your hand and confirm that the output voltage drops down.



In general, device interacts with your body as it uses it to close the circuit between device and earth. Your hand acts as a capacitor plate. When you adjust your device your hand has to be firm and steady attaching the handle of your device or your aluminum box.


Regards

Hi Jeg.I am not yet on sensor stage..The voltage I got is from the display circuit,the R10 from ic3a pin3..I will try to finish the sensor stage today..
ps..I do not have voltmeter so I used the 1 led display..

[FrancoItaly]

Originally Posted by Jeg

Hi Jh


Your voltage levels at sensor's output look that they are normal.
Assuming that your circuit is correct, then try the following.


When your voltmeter is connected alter your potentiometer to adjust again the buzzer/led threshold. Normally you will be able again to turn on your led.


Find a way to firm your meter's probes on the right points and then move your hands away to see if there is a variation on numbers. Then attach antenna with your hand and confirm that the output voltage drops down.



In general, device interacts with your body as it uses it to close the circuit between device and earth. Your hand acts as a capacitor plate. When you adjust your device your hand has to be firm and steady attaching the handle of your device or your aluminum box.


Regards

I state that the calibration inside the laboratory is difficult due to the many disturbances and the calibration must be done with the antenna inserted. Once the right value at the sensor stage output has been established, it connects to the display stage and any measurements, if the LEDs do not light up by varying the threshold, then the controls must be done on the display stage. If you want to measure the output on the collector of TR4 with the oscilloscope, the signal at the sensor stage output goes to zero.

[JHERICKU]

Thank u franco..I will finish the sensor stage today and update u so soon..Thank u..

[Jeg]

Originally Posted by JHERICKU

Hi Jeg.I am not yet on sensor stage..The voltage I got is from the display circuit,the R10 from ic3a pin3..I will try to finish the sensor stage today..
ps..I do not have voltmeter so I used the 1 led display..

There is a communication barrier my friend. When you finish your sensor with the antenna in place we talk again.


Tnks Franco

[Jeg]

Originally Posted by FrancoItaly

If you want to measure the output on the collector of TR4 with the oscilloscope, the signal at the sensor stage output goes to zero.

Why is that Franco? I don't remember noticing this. Oscilloscope has a high input impedance.

[FrancoItaly]

Originally Posted by Jeg

Why is that Franco? I don't remember noticing this. Oscilloscope has a high input impedance.

The oscilloscope has 1M impedance with few picofarads, however this is what happens, this shows how sensitive and critical the sensor stage is.

[JHERICKU]

Originally Posted by Jeg

There is a communication barrier my friend. When you finish your sensor with the antenna in place we talk again.


Tnks Franco

Hell Jeg..I have finish both the display and sensor..When I turn on there is a tiny sound coming from the buzzer..when I turn the potentiometer and trimmer there is no effect..no buzz and leds on only the tiny sound from the buzzer..

Ps.I used Bc547b,10k potentiometer trimmer..
where should I put the test probe to measure the output dc?
Thank u in advance..

I am sorry for my badproject..I am not an electronic eng noraquire formal education about electronic..I badly meeding this device so I am trying my best build..

[Jeg]

Hi friend
Looks like something is wrong, but wait for Franco to tell his opinion as he is very experienced on this.


(try connecting your voltmeter at the output of your sensor. When you touch the antenna, does the output signal drops?)

[FrancoItaly]

Originally Posted by Jeg

Hi friend
Looks like something is wrong, but wait for Franco to tell his opinion as he is very experienced on this.


(try connecting your voltmeter at the output of your sensor. When you touch the antenna, does the output signal drops?)

Yes, otherwise it could mean that there is a self oscillation. By touching the antenna a part of the signal on the base of TR2 (the mixer) is absorbed by the body and therefore the signal amplified by the sensor stage decreases slightly.

[JHERICKU]

Originally Posted by Jeg

Hi friend
Looks like something is wrong, but wait for Franco to tell his opinion as he is very experienced on this.


(try connecting your voltmeter at the output of your sensor. When you touch the antenna, does the output signal drops?)

I do not know where to put the test probe to measure the voltage..I have have no idea if it is droping or not..

This time I change te 10k potentiometer with 25k and remove the sensor stage for a while but there is no buzz and led ligths at all..I have noticed that when I touched everywhere on the board the led and buzzer beeps also..I think it is grounded..
Any suggestions my friend..

[FrancoItaly]

Originally Posted by JHERICKU

I do not know where to put the test probe to measure the voltage..I have have no idea if it is droping or not..

This time I change te 10k potentiometer with 25k and remove the sensor stage for a while but there is no buzz and led ligths at all..I have noticed that when I touched everywhere on the board the led and buzzer beeps also..I think it is grounded..
Any suggestions my friend..

The point to be measured is the output of the sensor stage, the one that goes to the input of the display stage. For the rest I don't know what to say, check the assembly carefully, maybe you made some mistakes.

[JHERICKU]

hello friend franco,Should I connect the negative probe of the multimeter to ground and the positive one to antenna to get the reading or the positive probe to transistor 04 emitter ?

I am so sorry..I have few knowledge about electronics..My apologies..

[JHERICKU]

Originally Posted by FrancoItaly

The point to be measured is the output of the sensor stage, the one that goes to the input of the display stage. For the rest I don't know what to say, check the assembly carefully, maybe you made some mistakes.

I put the probe on sensor output and I got 4.+volts. I touched the antenna and the voltage is thesame..why should I do?

[FrancoItaly]

Originally Posted by JHERICKU

hello friend franco,Should I connect the negative probe of the multimeter to ground and the positive one to antenna to get the reading or the positive probe to transistor 04 emitter ?

I am so sorry..I have few knowledge about electronics..My apologies..

The negative probe of the multimeter to ground and the positive to transistor 04 emitter.

[JHERICKU]

Originally Posted by FrancoItaly

The negative probe of the multimeter to ground and the positive to transistor 04 emitter.

I got 1.5 volts on transistor04 emitter with the trimmer on maximum..I have noticed that it beeps when I touched the board or the potentiometer and the antenna but the output not dropping..I believed the antenna is on positive line.It gives me 12v measurement..

[JHERICKU]

I remove the quartz and I got .044 volts on output..Can anyone have idea especially to franco if I got the correct output?
ps.I used 4mhz quartz..
Thank u for suggestions in advance..

[Rubin]

I would like to know who knows or has tested, if the franko circuit can detect nuggets.
I ask, because i have many signals from a place and i find only small nuggets.
I am comfused

[FrancoItaly]

Originally Posted by JHERICKU

I remove the quartz and I got .044 volts on output..Can anyone have idea especially to franco if I got the correct output?
ps.I used 4mhz quartz..
Thank u for suggestions in advance..

The sensor stage output measurement is on the emitter of TR5, not TR4.

[FrancoItaly]

Originally Posted by Rubin

I would like to know who knows or has tested, if the franko circuit can detect nuggets.
I ask, because i have many signals from a place and i find only small nuggets.
I am comfused

In theory, if the nuggets have been in that place for long enough, they should generate the phenomenon. The unknown is the size, I don't know if so small they emit a sufficient signal. The other explanation is that there are metals buried deeper than the range of the MDs and this may have happened in your case.