Laptop Metal Detector utilising Digital Lock-in Amplifier
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Posted by on August 13, 2008, 8:29 pm
Please log in for more thread options Is a powerful metal detector possible by using only laptop and sensor (search-head) without any additional electronics? See the generation and progress of this experimental project on: http://www.thunting.com/geotech/forums/showthread.php?t=14102 The metal detector uses only the sound-card (output/input) for interfacing the search-head. ;-) Aziz | |||||||||||||
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Posted by John Larkin on August 13, 2008, 10:40 pm
Please log in for more thread options On Wed, 13 Aug 2008 17:29:33 -0700 (PDT), oeguet@gmx.de wrote: Powerful in what sense? As compared to a real metal detector, no. John | |||||||||||||
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Posted by Bob Masta on August 14, 2008, 8:15 am
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On Wed, 13 Aug 2008 17:29:33 -0700 (PDT), oeguet@gmx.de wrote: >Is a powerful metal detector possible by using only laptop and sensor
>(search-head) without any additional electronics? > >See the generation and progress of this experimental project on: >http://www.thunting.com/geotech/forums/showthread.php?t=14102 > >The metal detector uses only the sound-card (output/input) for >interfacing the search-head. >;-) >Aziz I haven't looked into metal detectors, but my Daqarta system has a signal generator that can probably create any sort of driver signal you want, plus real-time spectral (or waveform) analysis of the input signal. It might be useful for development purposes, to try out concepts before you devote a lot of time to writing your own code. If you can explain the basic principles involved (or point me to a Website), I'll be able to give you a better idea of whether Daqarta can handle the task. (And if it can't do it now, it might be something to add to the next version!) Best regards, Bob Masta DAQARTA v4.00 Data AcQuisition And Real-Time Analysis www.daqarta.com Scope, Spectrum, Spectrogram, Sound Level Meter FREE Signal Generator Science with your sound card! | |||||||||||||
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Posted by Michael Black on August 14, 2008, 11:09 am
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On Thu, 14 Aug 2008, Bob Masta wrote: > On Wed, 13 Aug 2008 17:29:33 -0700 (PDT), oeguet@gmx.de wrote:
> >> Is a powerful metal detector possible by using only laptop and sensor
>> (search-head) without any additional electronics? >> >> See the generation and progress of this experimental project on: >> http://www.thunting.com/geotech/forums/showthread.php?t=14102 >> >> The metal detector uses only the sound-card (output/input) for >> interfacing the search-head. >> ;-) >> Aziz >
That page was too much to follow, too little detail and too many
> I haven't looked into metal detectors, but my Daqarta system has a > signal generator that can probably create any sort of driver signal > you want, plus real-time spectral (or waveform) analysis of the input > signal. It might be useful for development purposes, to try out > concepts before you devote a lot of time to writing your own code. > > If you can explain the basic principles involved (or point me to a > Website), I'll be able to give you a better idea of whether Daqarta > can handle the task. (And if it can't do it now, it might be > something to add to the next version!) > links. Many metal detectors work by having an oscillator with a coil that is open to the world. When metal comes close to the coil, that shifts the oscillator's frequency and that shift is the giveaway that there is metal. That won't work by merely feeding the coil with a signal, the coil has to be part of the signal generator. I seem to recall there are things where the metal acts as coupling between two coils, one excited by an oscillator and another a pickup, and then the amplitude in the second coil varies depending on the unknown metal. I suspect that is less workable than the first method, though the excitation coil does not have to be a part of the oscillator. From a memory of a Carl & Jerry story, I think the magnetometer uses a standalone excitation, and not that much more than a milk bottle filled with water and wound with wire. I can't remember what they used as a pickup. The problem is the question is based on some discussion somewhere, rather than based on a foundation of what a metal detector is. If the original poster had done some basic reading before asking here, he'd have a better idea of what was required, and maybe an idea of whether it's possible. Michael | |||||||||||||
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Posted by Rick on August 14, 2008, 1:27 pm
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> On Thu, 14 Aug 2008, Bob Masta wrote:
> > > On Wed, 13 Aug 2008 17:29:33 -0700 (PDT), oeguet@gmx.de wrote:
> > > >> Is a powerful metal detector possible by using only laptop and sensor
> >> (search-head) without any additional electronics? > >> > >> See the generation and progress of this experimental project on: > >> http://www.thunting.com/geotech/forums/showthread.php?t=14102 > >> > >> The metal detector uses only the sound-card (output/input) for > >> interfacing the search-head. > >> ;-) > >> Aziz > >
> > I haven't looked into metal detectors, but my Daqarta system has a > > signal generator that can probably create any sort of driver signal > > you want, plus real-time spectral (or waveform) analysis of the input > > signal. It might be useful for development purposes, to try out > > concepts before you devote a lot of time to writing your own code. > > > > If you can explain the basic principles involved (or point me to a > > Website), I'll be able to give you a better idea of whether Daqarta > > can handle the task. (And if it can't do it now, it might be > > something to add to the next version!) > > > That page was too much to follow, too little detail and too many
> links. > > Many metal detectors work by having an oscillator with a coil that > is open to the world. When metal comes close to the coil, that shifts > the oscillator's frequency and that shift is the giveaway that there > is metal. > > That won't work by merely feeding the coil with a signal, the coil > has to be part of the signal generator. > > I seem to recall there are things where the metal acts as coupling > between two coils, one excited by an oscillator and another a pickup, > and then the amplitude in the second coil varies depending on the > unknown metal. I suspect that is less workable than the first method, > though the excitation coil does not have to be a part of the oscillator. Most common today are the induction balance types. The various patents have a lot of thory. > From a memory of a Carl & Jerry story, I think the magnetometer uses
> a standalone excitation, and not that much more than a milk bottle filled > with water and wound with wire. I can't remember what they used as a > pickup. > > The problem is the question is based on some discussion somewhere, rather > than based on a foundation of what a metal detector is. If the original > poster had done some basic reading before asking here, he'd have a better > idea of what was required, and maybe an idea of whether it's possible. > > Michael > | |||||||||||||
>(search-head) without any additional electronics?