#26
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maybe you will have a hard time hearing because of sound from the quartz.
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#27
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#28
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Esteban, do you know this page? very well documented. regards, Fred. http://www.techlib.com/science/ion.html |
#29
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Thanks a lot! Regards Esteban |
#30
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http://www.google.com/patents?id=3gM...J&dq=6,107,791 Regards Esteban |
#31
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The patent shows that this quartz apparatus is designed to measure the near static charge of the air without disturbing it by using metal sensor wires. Does this mean you think we can locate long range metal targets by measuring only the near static charge of the air with a quartz sensor? Or is more circuitry needed to locate a long range target? Best wishes, J_P |
#32
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Can be useful for measure electric activity in site with long time buried metals. Maybe for 5 or 10 meters.
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#33
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This look interesting for electric field,not disturbing field.But what about magnetic field ? It is important too. Regards, Fred. |
#34
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Best wishes, J_P |
#35
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What i mean is : what Esteban intend to use if he wants to detect also the magnetic field? Regards, Fred. |
#36
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PASSIVE 1. magnetic system (absorptive) 2. electric system (type microvoltmeter) 3. combination of both (absorptive + microvoltmeter) 4. radiofrequency (simple radio receiver) (maybe sense combination of both - electric and magnetic fields) 5. Others... ACTIVE 1. I/B + RF sniffer (active + passive) 2. Off-resonance + RF sniffer (active + passive) 3. Other kind of MD + RF sniffer (active + passive) 4. IR beam + RF sniffer (active + passive) 5. Ultrasonic beam + RF sniffer (active + passive) 6. IR laser beam + RF sniffer (active + passive) 7. Other type based on emission + RF sniffer... 8. Etc. Here, RF sniffer can be simple FM radio. This combination + sensors you can use extend the possibilities. |
#37
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Ok thanks Esteban,
I see the common base is RF sniffer, enhanced by some other device.But to pick up RF you need RF to be generated somehow, what gives best results? Sorry for so many questions. regards, Fred. |
#38
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A bfo metal detector circuit with an exturnal coil generates an rf,long time buried metal at a distance will disturbe the rf in the coil,you can hear this little disturbance with an fm raido where the antenna is near the coil.I am building a unit but i do not know how to set the radio,do you set to a empty channel or one brodcasting?
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#39
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I have no idea.If you are generating a freqency, i suppose you should try to tune to this frequency? This looks interesting , it should be easy for you to try both .Did you really notice this effect? Regards, Fred. |
#40
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ACTIVE 1. I/B + RF sniffer (active + passive) 2. Off-resonance + RF sniffer (active + passive) 3. Other kind of MD + RF sniffer (active + passive) 4. IR beam + RF sniffer (active + passive) 5. Ultrasonic beam + RF sniffer (active + passive) 6. IR laser beam + RF sniffer (active + passive) 7. Other type based on emission + RF sniffer... 8. Etc. Here, RF sniffer can be simple FM radio. |
#41
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Hi Fred,i have not experimented with this before,but if you read the posts from ESTABAN in the last several months he givs hints on how the pistol detectors from the past worked,he knows what he is talking about.I am building a bfo metal detecter based on a microchip circuit with an external coil of 70 turns of wire,the only problem is it occilates at 88 kilohertz,this may be two low,i will run a sheiled cable from the antenna conection of a hand helded fm raido to a loop antenna near the coil of the bfo.
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#42
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Best wishes, J_P |
#43
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about this "RF sniffer" or FM radio what do you mean ? Someone already asked this... I mean... what you do with FM radio ? tune to a broadcast station ? Tune to free slot (just background noise) ? Or just modify the radio for change e.g. frequency ...bands etc ? I don't understand what's the purpose of this RF sniffer. Kind regards, Max
__________________
"Kill for gain or shoot to maim... But we dont need a reason " someone said... |
#44
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yes right... but he wrote also that this "RF sniffer" works in FM : and I read this both frequency modulation and FM-band ...if he doesn't modify the radio he will tune e.g. from 88-108MHz and so ? What's relationship between a 50KHz signal not modulated in frequency (do you know any detector that made this modulation of signal ???) and a frequency modulation receiver that maybe runs at 88Mhz (if he doesn't modify radio) ??? This thing seems have no sense. But maybe he will explain us what kind of relationship will be between the two things! Kind regards, Max
__________________
"Kill for gain or shoot to maim... But we dont need a reason " someone said... |
#45
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Is better modify the radio quite one turn of the 3 turns used in FM, so this extend to 108 to 130 or more Mhz, out of poluited FM here we have. Also I want to know how is the purpose of the antenna (no telescopic, I use only a cable around search head), but is useful for to detect this old items, and don't know why, maybe rediadated signals from different radio sources... Also the audio is useful for to ampplify the BFO detection... This is an empiric theme, because as you don't have scientific papers in this field, your way is the experiment and see wich is better results. |
#46
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Isn't in books! |
#47
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Yes, more low frequencies mean minus hertz variation. "Excess" of Khz (300) you have here detected very well paper plated of box cigarettes...
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#48
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some FM radios (almost all old stuff as far as I know) can detect small amplitude modulation (narrow) when they are in frequency demodulation mode. This happens cause of some transistor there that works as rectifier and then some detection happens by amplitude too not just frequency modulation. My guess is that, if you put the coil with tone signal (amplitude modulation) near radio in FM mode... it will pick up that tone by amplitude demodulation that happens there. Very easy to test... nedd just one e.g. remote control and an FM radio... put it into FM and near the remote on the back side... the inductive coupling between radio coils and remote tracks with currents flowing in... will give you hear the sound of on-off modulation at IR led(s)... so to sense the currents and relative EM fields. But if you switch in AM mode you will hear much more loud... cause it's dedicated demodulator there... with e.g. germanium diodes (old stuff radio like you posted). My question is: why use FM if you look for amplitude modulation ? When you talk about BFO you mean there's some frequency mixing somewhere and this will be detected by FM radio as frequency (variant) modulation ... and thus amplitude modulation residual information is just a part of what you are looking for? Kind regards, Max
__________________
"Kill for gain or shoot to maim... But we dont need a reason " someone said... |
#49
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I use FM mode because is very more clean than AM. If you don't use the IR or loop for to generate the tone, or BFO MD, or I-B MD in conjunction FM radio, only the FM radio, well also works only the FM and don't know why! Also any RF clean receiver... For example, I bought a wireless bell and I use the receiver part (only for check if this can be useful), well also works. |
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