A good digital oscilloscope?
in [Design]
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From: Jim Yanik on 13 Dec 2009 22:40 "Tim Williams" <tmoranwms(a)charter.net> wrote in news:hg3eqf$i8$1(a)news.eternal-september.org: > What madness drove them to hybrid > tube/SS circuits, who knows! ;-) > > Tim > It was just the natural progression to solid state,as transistors in those early days could not handle some of the voltages or fast speeds. After all,the CRT was still a "tube",for a long time. now many scopes use LCD displays. 21.5 years at TEK field service centers,repairing and calibrating TEK scopes and TV test equipment. -- Jim Yanik jyanik at localnet dot com
From: Jim Yanik on 13 Dec 2009 22:43 "Tim Williams" <tmoranwms(a)charter.net> wrote in news:hg3l20$kf0$1(a)news.eternal-september.org: > "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in > message news:4ogai51nv3vosmev14ug9mljcp10059368(a)4ax.com... >> The 545-547 scope front panels were wonderful. You could grab a fist >> full of knob, with serious detents, and wail away. They were a >> pleasure to drive. >> >> Kids these days. > > You've got a point about "fistful of knob" and "drive". well,those tube monsters had REAL switches in them! > > Tim > to use a scope these days,you have to go through menus. Pretty soon,all TEK scopes will be made in China. (they're moving production there) -- Jim Yanik jyanik at localnet dot com
From: Tim Williams on 13 Dec 2009 23:34 "Jim Yanik" <jyanik(a)abuse.gov> wrote in message news:Xns9CE0E6C498709jyaniklocalnetcom(a)216.168.3.44... > It was just the natural progression to solid state,as transistors in those > early days could not handle some of the voltages or fast speeds. Yeah, they put them in bizarre places, like double cascodes... the transistor has "no" voltage across it, so it can do fairly good bandwidth, while somehow amplifying the signal below it (in voltage terms I suppose). And other circuits altogether weirderer. "No" voltage is a lie, of course, because tubes have far less transconductance than BJTs. A tube cascode is rather squishy, so the transistor would still have some ways to go in terms of voltage gain. It might operate on a fairly adequate loadline as far as making real power (delta V * delta I). I like how the late model plugins ran from the same +/-150V or whatever supply they gave them, but almost all of that was pure resistor: they ran ~15V zener regulators off them instead. The equivalent transistor circuit used exactly as much current, with a tenth the voltage, and gave at least as much bandwidth. It's interesting how tubes operate with similar impedances and capacitances as transistors (within an order of magnitude), with less gain and about 10 times the voltage wasted. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: JosephKK on 14 Dec 2009 02:00 On Sun, 13 Dec 2009 10:08:24 -0800, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >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 > I looked at the decay chains first, for reasonable half lives of Radium. I missed the Ra 226 in the uranium chain. It has a half life of 1600 years. It also turns out (probably for the very reason of the higher half life) that it is the most abundant in nature. The 25 year claim based on natural abundance seems reasonable for the half life(s) involved. Note also that Ra 226 is an alpha emitter rather than a beta emitter like Ra 228. A little safer to have close to the body.
From: JosephKK on 14 Dec 2009 02:04
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. > >I never did completely understand the circuit in this thing (I have the kit >instructions, so I have all the drawings), it's drawn so as to make a >minimum of sense. > >Tim Without the circuit diagram i am loath to explain the various less than obvious controls. |