low-end scope
in [Design]
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From: miso on 2 Mar 2010 14:27 On Mar 2, 6:57 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Mon, 1 Mar 2010 21:08:45 -0800 (PST), "m...(a)sushi.com" > > > > <m...(a)sushi.com> wrote: > >On Mar 1, 12:32 pm, John Larkin > ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Mon, 01 Mar 2010 11:27:08 -0800, VWWall <vw...(a)large.invalid> > >> wrote: > > >> >John Larkin wrote: > > >> >> I'd like to have a low-end scope or two to keep around the house, > >> >> occasional use only. I could use it at work, too, for simple analog > >> >> stuff, timing software execution, stuff like that. > > >> >> I was think about a Rigol DS1052E, 50 MHz color, 2 traces, about $535. > >> >> Or something like that. Any suggestions or comments? > > >> >How about one of those scopes that plug into the USB socket of your > >> >computer? > > >> >saelig competes with Rigol, and has PC scopes as well: > > >> >http://www.saelig.com/category/PSPCEL.htm > > >> >Just a thought. With the price of net-book type PC's as low as it is, a > >> >separate PC just for test equipment use might be economical. > > >> I'd rather not have a scope that runs Windows and that needs two > >> boxes, drivers, a USB cable, and a mouse to do anything. A real scope > >> will most likely still be working 20 years from now. I like real > >> scopes with lots of real knobs. > > >> A USB scope would make sense in some data-centric application where > >> the waveform needs to be shipped into Matlab or some such in real > >> time. > > >> John > > >http://www.bitscope.com/ > >has linux and windows. > > >Personally, I'd get a used pre-Chinese Tek scope. DeAnza and Livermore > >swap meets will be starting up soon. > > I used to get up before dawn to go to the Foothill flea market, but > ebay kind of killed it off. One met personalities there... Jim > Williams, Bob Pease, Peter Alfke. > > John Ah yes, Bob Pease selling his book out of the boot of his VW. Those were the days. I got my Tek 11402A at Livermore two years ago for $250. Nobody would pay to ship that beast. The problem with DeAnza and Livermore is you need to go often, and often there is nothing but junk. Livermore is this weekend, provided the site isn't too muddy.
From: John Larkin on 2 Mar 2010 14:53 On Tue, 02 Mar 2010 17:04:43 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Tue, 02 Mar 2010 08:17:55 -0800) it happened John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in ><n5eqo597obv5faqni99sjvn5k826fugvbr(a)4ax.com>: > >>It is in the sense that no audio signal has anything like the s/n to >>justify a 24-bit ADC or DAC, even if a real 24-bit part existed. And >>the idea of even 12 bit linearity is silly when you are using >>microphones, power amps, loudspeakers, and signal trains that >>deliberately add distortion. > >Yes, and the brain has ways of removing unwanted noises. >Personally in my place the environment noise would make 8 bit audio sufficient in many cases. >I have runs tons of stuff through companders. >Only late at night I would need 16 bits... > >OTOH the ear (or our hearing) is very much logarithmic, >so we hear distortions even in very low volume passages. > > > >>But if I have 1 PPM of hum or DC offset in my NMR coil drivers, or 100 >>PPM pos/neg asymmetry, users *will* complain. > >100 PPM is only a factor 10000, not even 14 bits. > > >>And how does an analog scope work better than a digital scope when >>testing a 24-bit DAC? > >To reformulate the question: >How are you gonna look at such a signal with an 8 bit ADC as in your scope? >By putting some analog gain up front? > I do have a Tek AM503 that I sometimes use to front-end a digital scope. It's a differential amplifier with switchable gain to 100K, DC offset, and switchable low and high cutoff frequencies. Its overload recovery is better than most any current-production analog or digital scope can achieve. http://www.leftfield.org/~dd/images/TE/TekAM502.jpg John
From: Jan Panteltje on 2 Mar 2010 16:58 On a sunny day (Tue, 02 Mar 2010 11:53:29 -0800) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <d6qqo5p3rclqov1vi058nihgddv1qfi5b6(a)4ax.com>: >On Tue, 02 Mar 2010 17:04:43 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>On a sunny day (Tue, 02 Mar 2010 08:17:55 -0800) it happened John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >><n5eqo597obv5faqni99sjvn5k826fugvbr(a)4ax.com>: >> >>>It is in the sense that no audio signal has anything like the s/n to >>>justify a 24-bit ADC or DAC, even if a real 24-bit part existed. And >>>the idea of even 12 bit linearity is silly when you are using >>>microphones, power amps, loudspeakers, and signal trains that >>>deliberately add distortion. >> >>Yes, and the brain has ways of removing unwanted noises. >>Personally in my place the environment noise would make 8 bit audio sufficient in many cases. >>I have runs tons of stuff through companders. >>Only late at night I would need 16 bits... >> >>OTOH the ear (or our hearing) is very much logarithmic, >>so we hear distortions even in very low volume passages. >> >> >> >>>But if I have 1 PPM of hum or DC offset in my NMR coil drivers, or 100 >>>PPM pos/neg asymmetry, users *will* complain. >> >>100 PPM is only a factor 10000, not even 14 bits. >> >> >>>And how does an analog scope work better than a digital scope when >>>testing a 24-bit DAC? >> >>To reformulate the question: >>How are you gonna look at such a signal with an 8 bit ADC as in your scope? >>By putting some analog gain up front? >> > >I do have a Tek AM503 that I sometimes use to front-end a digital >scope. It's a differential amplifier with switchable gain to 100K, DC >offset, and switchable low and high cutoff frequencies. Its overload >recovery is better than most any current-production analog or digital >scope can achieve. > >http://www.leftfield.org/~dd/images/TE/TekAM502.jpg > >John Nice knobs! That is the kind of controls that I like :-)
From: Joerg on 2 Mar 2010 18:25 Nico Coesel wrote: > Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: > >> On a sunny day (Mon, 01 Mar 2010 17:46:33 -0800) it happened John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >> <r4roo5dd2mjre06t8glvpun5dc9hgu9p53(a)4ax.com>: >> >>> On Mon, 01 Mar 2010 16:49:54 -0800, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Jan Panteltje wrote: >>>>> On a sunny day (Mon, 01 Mar 2010 15:30:11 -0800) it happened John Larkin >>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>> <h5joo5tu7iv486nr7g4pp69r0vpco1cnuc(a)4ax.com>: >>>>> >>>>>> I've gotten used to small, light, color digital scopes >>>>> Mine has color too: Green. >>>> >>>> Mine even glows in the dark. Now that's something DSOs can't do :-) >>> Yeah, but how long can you hold it out at arm's length? >>> >>> Now whenever I use an analog scope - which is seldom - I get confused >>> about which trace is which. I don't miss black+white TV sets, or >>> typewriters and carbon paper, or analog VOMs, or slide rules, or 300 >>> baud acoustic modems either. >>> >>> John >> Wow, and that from somebody who swears by writing and drawing on deads trees :-) >> And I do not miss the noise of that horrible Tek digital I once had to use for audio. > > Probably a TDS200 series. There are noisy as hell. > Watch out for 40/80kHz conductive noise leaking out of its backlight inverter. Those things were IMHO a disgrace to Tektronix. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 2 Mar 2010 18:49
On Tue, 02 Mar 2010 18:14:33 GMT, nico(a)puntnl.niks (Nico Coesel) wrote: >Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: > >>On a sunny day (Mon, 01 Mar 2010 17:46:33 -0800) it happened John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >><r4roo5dd2mjre06t8glvpun5dc9hgu9p53(a)4ax.com>: >> >>>On Mon, 01 Mar 2010 16:49:54 -0800, Joerg <invalid(a)invalid.invalid> >>>wrote: >>> >>>>Jan Panteltje wrote: >>>>> On a sunny day (Mon, 01 Mar 2010 15:30:11 -0800) it happened John Larkin >>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >>>>> <h5joo5tu7iv486nr7g4pp69r0vpco1cnuc(a)4ax.com>: >>>>> >>>>>> I've gotten used to small, light, color digital scopes >>>>> >>>>> Mine has color too: Green. >>>> >>>> >>>>Mine even glows in the dark. Now that's something DSOs can't do :-) >>> >>>Yeah, but how long can you hold it out at arm's length? >>> >>>Now whenever I use an analog scope - which is seldom - I get confused >>>about which trace is which. I don't miss black+white TV sets, or >>>typewriters and carbon paper, or analog VOMs, or slide rules, or 300 >>>baud acoustic modems either. >>> >>>John >> >>Wow, and that from somebody who swears by writing and drawing on deads trees :-) >>And I do not miss the noise of that horrible Tek digital I once had to use for audio. > >Probably a TDS200 series. There are noisy as hell. My usual scope is a TDS2012. It shows a little trace noise, but it doesn't bother me. An analog scope trace would be as fuzzy, unless you use an old 547 with a two-foot-long CRT. Analog scopes just aren't quantitative like digitals are: ftp://jjlarkin.lmi.net/RTD_in_air.JPG Of course, audio isn't quantitative. John |