#2776
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It's ok when the output voltage of the sensor stage reaches its maximum. |
#2777
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Hi dear friend Mr jeg
Your plan will not work properly |
#2778
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Hi hoshi
What do you mean my friend? Its a simple differential amplifier. https://www.electronics-tutorials.ws/opamp/opamp_5.html |
#2779
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2780
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Ps..I used the display with 1 led..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2781
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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 |
#2782
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ps..I do not have voltmeter so I used the 1 led display..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2783
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#2784
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Thank u franco..I will finish the sensor stage today and update u so soon..Thank u..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2785
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There is a communication barrier my friend. When you finish your sensor with the antenna in place we talk again. Tnks Franco |
#2786
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Why is that Franco? I don't remember noticing this. Oscilloscope has a high input impedance. |
#2787
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The oscilloscope has 1M impedance with few picofarads, however this is what happens, this shows how sensitive and critical the sensor stage is.
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#2788
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2789
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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?) |
#2790
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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.
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#2791
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2792
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#2793
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2794
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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?
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2795
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The negative probe of the multimeter to ground and the positive to transistor 04 emitter.
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#2796
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2797
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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..
__________________
Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you... |
#2798
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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
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#2799
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The sensor stage output measurement is on the emitter of TR5, not TR4.
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#2800
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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.
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