In comp.dsp GreenXenon <glucegen1x@gmail.com> wrote: (snip)> Are there any devices that can detect, receive, record, playback, > modulate/demodulate, transmit and/or otherwise process signals with > peak-to-peak amplitudes around 1 femtovolt?Since it is usually power, and not voltage, that is the limiting factor, it might be possible if the current is high enough. If you go through a transformer, or a series of them, to get to a more usual voltage and current range, then it might work. I would say that it is likely not possible to measure femtovolts DC, but likely possible AC. -- glen
What is the smallest physically-possible voltage that can be detected or processed given the state of today's technology?
Started by ●June 1, 2009
Reply by ●June 2, 20092009-06-02
Reply by ●June 2, 20092009-06-02
On Tue, 02 Jun 2009 18:03:42 +1000, F Murtz <haggisz@hotmail.com> wrote:>Eric Gisse wrote: >> On Jun 1, 4:15 pm, GreenXenon <glucege...@gmail.com> wrote: >>> Hi: >>> >>> What is the smallest physically-possible voltage that can be detected >>> or processed given the state of today's technology? >>> >>> Thanks >> >> Oh my god please fuck off from sci.physics. We do not want you. >Is there any one in this group with the necessary scholastic >qualifications to diagnose the reason this poster asks such esoteric >questionsHe seems interested in the issues but confused about physical units. I suppose I should get on with writing my book, to make all this stuff plain. John
Reply by ●June 2, 20092009-06-02
On Tue, 02 Jun 2009 12:25:54 +0100, Richard Dobson <richarddobson@blueyonder.co.uk> wrote:>F Murtz wrote: >> Eric Gisse wrote: >>> On Jun 1, 4:15 pm, GreenXenon <glucege...@gmail.com> wrote: >>>> Hi: >>>> >>>> What is the smallest physically-possible voltage that can be detected >>>> or processed given the state of today's technology? >>>> >>>> Thanks >>> >>> Oh my god please fuck off from sci.physics. We do not want you. >> Is there any one in this group with the necessary scholastic >> qualifications to diagnose the reason this poster asks such esoteric >> questions > >It probably needs someone from the astronomical and satellite-making >communities (and maybe folk at Cern et al), who have necessarily to deal >with the smallest detectable signals; and the answer will (a) probably >have to do with the lowest-achievable noise (C --> Absolute Zero), and >(b) change regularly as new technology is developed to see further back >in space/time, and to detect smaller and smaller (etc) particles. To >these folks, a photon or an electron is probably pretty loud. > >The best I can suggest is to start with picovolts and work downwards, >e.g. (from a quick google search): > >http://www.emelectronics.co.uk/spec/P12.html >http://www.maa.org/mathland/mathtrek_7_27_98.html > >Are yattovolts measured anywhere? I had not known of this unit until >this question popped up, so I am already grateful for learning something >new, even if its everyday usage is (for me) rather limited. > > >sci.physics appears not to be on the list. If it is a legitimate albeit >esoteric question, I would have thought they would be the most likely to >enjoy both the question and its answers. Though I have observed that as >a general rule, people on newsgroups prefer questions that have answers >that can be both definitive and short. Perhaps this is not one of those? > >Richard DobsonI bought a nice old Keithley electrometer on ebay. Analog-needle meter. Its lowest range is +- 1e-14 amps. Cool stuff. John
Reply by ●June 2, 20092009-06-02
On Jun 2, 12:17�am, "Michael A. Terrell" <mike.terr...@earthlink.net> wrote:> rickman wrote: > > > On Jun 1, 10:33 pm, ItsASecretDummy > > <secretasian...@thebarattheendoftheuniverse.org> wrote: > > > On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin > > > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > > > >Single-electron transistors can sense, well, single electrons. > > > > >John > > > > � PMTs can be good enough to detect single photon events. > > > Hmmm... �I have a $35 digital multimeter that can measure exactly 0 > > volts! > > � � No, it can't. �It can display zero, even with some voltage at the > input. �The issues is the resolution of the meter. �Even with the probes > shorted, you will have some Johnson noise which is generated by the > resistors in the input circuitry, if the meter is above absolute zero > degrees. That voltage is too low to be displayed, but it is still there. > > -- > You can't have a sense of humor, if you have no sense!That was my point. It was supposed to be funny... I guess I needed to add the smiley. One of the things I have thought about is when in court defending a ticket for not stopping at a stop sign, asserting that there is no defense possible since you can never prove a quantity is exactly zero by measurement. Somehow I suspect the interesting aspects of this defense would be lost on the judge... Rick
Reply by ●June 2, 20092009-06-02
On Jun 2, 9:08�am, Jerry Avins <j...@ieee.org> wrote:> rickman wrote: > > �> On Jun 1, 10:33 pm, ItsASecretDummy�> <secretasian...@thebarattheendoftheuniverse.org> wrote: > > �>> On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin > �>>�>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > �>> > �>>> Single-electron transistors can sense, well, single electrons. > �>>> John > �>> � PMTs can be good enough to detect single photon events. > �> > �> Hmmm... �I have a $35 digital multimeter that can measure exactly 0 > �> volts! > > How exactly? > > JerryThe usual way. It's not a magic voltmeter! Rick
Reply by ●June 2, 20092009-06-02
On Jun 2, 12:03�pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:> In comp.dsp GreenXenon <glucege...@gmail.com> wrote: > (snip) > > > Are there any devices that can detect, receive, record, playback, > > modulate/demodulate, transmit and/or otherwise process signals with > > peak-to-peak amplitudes around 1 femtovolt? > > Since it is usually power, and not voltage, that is the limiting > factor, it might be possible if the current is high enough. > > If you go through a transformer, or a series of them, to get > to a more usual voltage and current range, then it might work. > I would say that it is likely not possible to measure femtovolts DC, > but likely possible AC. > > -- glenCan't you always chop a DC current to produce an AC current? Even if the current is very high, the fact that it is at a very low voltage makes it hard to get any of that current to flow through your measuring device, even if it is a transformer. I suppose that you could pass the entire current through the measuring device and then calculate the voltage by knowing the impedance... But I don't see how having a high current help a direct measurement of a low voltage. Rick
Reply by ●June 2, 20092009-06-02
rickman wrote:> > On Jun 2, 12:17 am, "Michael A. Terrell" <mike.terr...@earthlink.net> > wrote: > > rickman wrote: > > > > > On Jun 1, 10:33 pm, ItsASecretDummy > > > <secretasian...@thebarattheendoftheuniverse.org> wrote: > > > > On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin > > > > > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > > > > > > >Single-electron transistors can sense, well, single electrons. > > > > > > >John > > > > > > PMTs can be good enough to detect single photon events. > > > > > Hmmm... I have a $35 digital multimeter that can measure exactly 0 > > > volts! > > > > No, it can't. It can display zero, even with some voltage at the > > input. The issues is the resolution of the meter. Even with the probes > > shorted, you will have some Johnson noise which is generated by the > > resistors in the input circuitry, if the meter is above absolute zero > > degrees. That voltage is too low to be displayed, but it is still there. > > > > -- > > You can't have a sense of humor, if you have no sense! > > That was my point. It was supposed to be funny... I guess I needed > to add the smiley. > > One of the things I have thought about is when in court defending a > ticket for not stopping at a stop sign, asserting that there is no > defense possible since you can never prove a quantity is exactly zero > by measurement. Somehow I suspect the interesting aspects of this > defense would be lost on the judge...Judges don't have a sense of humor, and most have no common sense. -- You can't have a sense of humor, if you have no sense!
Reply by ●June 2, 20092009-06-02
Eric Jacobsen wrote:> > "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message > news:CMudnRFLId9xOrnXnZ2dnUVZ_qCdnZ2d@earthlink.com... > > > > rickman wrote: > >> > >> On Jun 1, 10:33 pm, ItsASecretDummy > >> <secretasian...@thebarattheendoftheuniverse.org> wrote: > >> > On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin > >> > > >> > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> > > >> > >Single-electron transistors can sense, well, single electrons. > >> > > >> > >John > >> > > >> > PMTs can be good enough to detect single photon events. > >> > >> Hmmm... I have a $35 digital multimeter that can measure exactly 0 > >> volts! > > > > > > No, it can't. It can display zero, even with some voltage at the > > input. The issues is the resolution of the meter. Even with the probes > > shorted, you will have some Johnson noise which is generated by the > > resistors in the input circuitry, if the meter is above absolute zero > > degrees. That voltage is too low to be displayed, but it is still there. > > > > > > -- > > You can't have a sense of humor, if you have no sense! > > Yeah, but when it's exactly zero volts, that what the $35 multimeter will > display, so he wasn't incorrect. > > ;)Sigh. -- You can't have a sense of humor, if you have no sense!
Reply by ●June 2, 20092009-06-02
All responders have been suckered by the green monster. Bill -- Most people go to college to get their missing high school education.
Reply by ●June 2, 20092009-06-02
In comp.dsp Salmon Egg <SalmonEgg@sbcglobal.net> wrote:> > All responders have been suckered by the green monster.That is true, but the femtovolt question is interesting, independent of who asked it. I base my replies on the question, not the questioner. It might be that the answer is independent of the original question. -- glen
