A good digital oscilloscope?
in [Design]
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From: John Larkin on 13 Dec 2009 13:08 On Sun, 13 Dec 2009 08:04:08 -0800, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Thu, 10 Dec 2009 10:11:28 -0800, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On 10 Dec 2009 17:26:14 GMT, Robert Latest <boblatest(a)yahoo.com> >>wrote: >> >>>Joerg wrote: >>> >>>> Back in those days watch dials would be readable all night, not nearly >>>> have that much decay. That is no longer the case, no matter what fancy >>>> material they use. >>> >>>I wonder if the phosphorescence of that radium compound has anything to >>>do with the radium's radioactivity. Maybe the radioactivity helps to get >>>the energy into or back out of the long-term storage states. >>> >>>robert >> >>Of course it does. Radium phosphors will glow in the dark for >>centuries. That's what the radium is for. Tritium too, except its >>half-life is around 12 years. >> >>John >> >Roger on the beta decay driving the luminescence. But not on the centuries >life, the half life of Radium 228 is only 5.7 years. Wiki claims 1% loss in 25 years, I presume from natural radium. 50-year-old clocks and watches still glow. I'd suspect radiation damage to phosphors might be a factor too. http://en.wikipedia.org/wiki/Radium#Radioactivity http://en.wikipedia.org/wiki/Isotopes_of_radium John
From: Jim Thompson on 13 Dec 2009 13:17 On Sun, 13 Dec 2009 09:46:00 -0800, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Fri, 11 Dec 2009 16:19:47 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com/Snicker> wrote: > >>On Fri, 11 Dec 2009 14:55:01 -0800, Charlie E. <edmondson(a)ieee.org> >>wrote: >> >>>On Fri, 11 Dec 2009 11:32:44 -0800, Joerg <invalid(a)invalid.invalid> >>>wrote: >>> >>>>Joel Koltner wrote: >>>>> "Joerg" <invalid(a)invalid.invalid> wrote in message >>>>> news:7ob08jF3oortqU1(a)mid.individual.net... >>>>>> But wait, $600 for a Christmas gift? Ain't that a bit over the top? >>>>> >>>>> Only a little... I think that $250-$500 per kid for Xmas today is not at >>>>> all uncommon today... >>>>> >>>>>> As a kid I had to work for stuff like that. For example at a meat >>>>>> factory until I had the $400 for my first used and pretty banged up >>>>>> HW100 transceiver. >>>>> >>>>> I doubt you can legally work at a meat factory unless you're at least 18 >>>>> today. :-( >>>>> >>>>> If you want to see some kids with wealthy parents who are *seriously* >>>>> spoiled, check this out: >>>>> http://www.mtv.com/shows/sweet_16/episodes.jhtml . It's not uncommon on >>>>> that show for the parents to blow $25-$100k on their kid's 16th birthday! >>>>> >>>>> If I had the choice between a Lexus and, I dunno, a Civic and a bunch of >>>>> test equipment, I think it'd be obvious which I'd choose... >>>>> >>>> >>>>What I really don't understand is when a couple goes into big time debt >>>>just for the wedding ceremony, and often the bride's folks as well. I've >>>>heard of one couple who "had to" sell their home and move into an >>>>apartment to give their daughter an "appropriate" wedding. >>>> >>>>We made sure that neither of our parents had to pay anything and that >>>>our wedding ceremony was reasonable and could be comfortably paid from >>>>our savings (without raiding the account). Credit card use for the >>>>wedding was zilch. >>> >>>Ah, Jeorg, we are so much alike! >>> >>>When we got married, we were still in college, so had a small ceremony >>>there. We paid for the flowers, the photos (a real mess, but then we >>>were young then, and didn't know to get things in writing!) the cakes, >>>etc. We didn't even HAVE a credit card at the time! Her folks helped >>>out on some of the expenses, and her mom made the dress. I just >>>rented a tux. It was simple, and inexpensive, and still very >>>memorable! >>> >>>Charlie >> >>Went to the minister's house and got married for FREE... >>_50_years_ago_this_coming_March_31_ ;-) >> >> ...Jim Thompson > >Look him up and have a nice dinner with him about that time (provided 'e is >still around). (Or on some chance her). He'd be around 110 years old ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Help save the environment! Please dispose of socialism properly!
From: Jan Panteltje on 13 Dec 2009 13:17 On a sunny day (Sun, 13 Dec 2009 17:46:14 GMT) it happened Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote in <hg399d$2na$1(a)news.albasani.net>: >On a sunny day (Sun, 13 Dec 2009 09:02:40 -0800) it happened Joerg ><invalid(a)invalid.invalid> wrote in <7okl1iF3qgfqrU1(a)mid.individual.net>: > >>They work similar to an injection oscillator where mildly force-feeding >>it some signal makes it synchronize to that signal. More or less, >>depending on how strong you tie them together. Problem with synchronizer >>scopes is that the user really has to watch it. Crank up the stabilizer >>knob too much will make it appear rock stable but will distorte the >>signal that's being shown. IOW, what you see is not necessarily what you >>get. The X-axis (time) becomes non-linear. > > >Then the design is wrong. OK, forget it, this is not an injection osc.
From: John Larkin on 13 Dec 2009 13:42 On Sun, 13 Dec 2009 10:45:45 -0600, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"JosephKK" <quiettechblue(a)yahoo.com> wrote in message >news:vr5ai5tjh0b59t76e4362bufh7ufgp0n97(a)4ax.com... >> The last time i saw a synchronizer type 'scope was over 40 years ago, it >> was a neighbors prize possession and 10+ years old even then. > >http://webpages.charter.net/dawill/tmoranwms/Elec_Scope1_lg.jpg > >Well, it says "TRIG LEVEL" on the outer knob, but it has this peculiar >"STABILITY" on the inner knob. Older triggered-sweep scopes, like the Tek 545, had a "stability" knob. It usually set the threshold of the Schmitt trigger that followed the trigger discriminator. At high trigger frequencies, one would tweak it for a stable display. Turning the stability knob one way would free-run the timebase (before "auto" was invented), the other way would kill it. http://www.barrytech.com/tektronix/vintage/tek545bfront.jpg Later scopes, with faster (tunnel diode and such) trigger logic, didn't need this. John
From: Tim Williams on 13 Dec 2009 14:12
"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> wrote in message news:hg399d$2na$1(a)news.albasani.net... > Consider this circuit: Ewwww! An UJT! It's a bad scope, okay, but not THAT bad! ;-) > The Venier speed ('stability?') is set by R1, and set a bit lower in > frequency (or fraction of that) then the signal observed. No, that's a bad way to control stability, you'd want to control dead time or discharge time (the latter isn't possible with an UJT). As shown, you're changing dV/dt, which needs to be in calibrated ranges. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |