Reply by Robert Baer June 8, 20122012-06-08
Tim Williams wrote:
> "Robert Baer" <robertbaer@localnet.com> wrote in message > news:IOudndz8kuCSak3SnZ2dnUVZ_qWdnZ2d@posted.localnet... >> Dual triode..makes me think of the classical 6SN7..tho for slightly >> less space, 12AU7, 12AT7 or 12AX7 (any one or mix them as the mu is >> not relevant with a decent FF design). >> Or for even less space, a pair of nuvistors may do.. > > I have a couple 12AX7 "computor" tubes. Flat (not embossed), gray plate, > "diamond base" (diamond impression in the center of the glass button > base), made in E. Germany. Not labeled Telefunken, but signs point to > it. Supposedly tubes like this are ridiculously expensive. I should put > them on eBay some time and see what happens. > > Tim >
Do an e-bay price search first and pick a starting number (say) in the 60 percentile with a "buy it now" (say) in the 90 percentile.
Reply by Gerhard Hoffmann June 7, 20122012-06-07
Am 08.06.2012 00:30, schrieb Tim Williams:

> I have a couple 12AX7 "computor" tubes. Flat (not embossed), gray plate, > "diamond base" (diamond impression in the center of the glass button > base), made in E. Germany. Not labeled Telefunken, but signs point to > it.
But Telefunken would be W.Germany. BTW I had the fun to visit the TWT production in Ulm that used to be Telefunken (now Thales). For me as a RF guy that was kinda wierd.. no semiconductors, no circuits, no boards, only fine mechanics, gas, metals, vacuum, glass, magnets and then, finally, ..... a huge array of SHF network analyzers. Impressive. Gerhard
Reply by Tim Williams June 7, 20122012-06-07
"Robert Baer" <robertbaer@localnet.com> wrote in message 
news:IOudndz8kuCSak3SnZ2dnUVZ_qWdnZ2d@posted.localnet...
> Dual triode..makes me think of the classical 6SN7..tho for slightly less > space, 12AU7, 12AT7 or 12AX7 (any one or mix them as the mu is not > relevant with a decent FF design). > Or for even less space, a pair of nuvistors may do..
I have a couple 12AX7 "computor" tubes. Flat (not embossed), gray plate, "diamond base" (diamond impression in the center of the glass button base), made in E. Germany. Not labeled Telefunken, but signs point to it. Supposedly tubes like this are ridiculously expensive. I should put them on eBay some time and see what happens. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by Bill Sloman June 7, 20122012-06-07
On Jun 7, 7:15=A0pm, John Larkin <jlar...@highlandtechnology.com> wrote:
> On Tue, 5 Jun 2012 10:13:08 -0700 (PDT), Bill Sloman > > <bill.slo...@ieee.org> wrote: > >On Jun 5, 5:55 pm, John Larkin > ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT),BillSloman > > >> <bill.slo...@ieee.org> wrote: > >> >On Jun 5, 4:16 pm, John Larkin > >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman > > >> >> <bill.slo...@ieee.org> wrote: > >> >> >On Jun 4, 6:31 pm, John Larkin > >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman > > >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >On Jun 4, 4:09 pm, John Larkin > >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> >> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman > > >> >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >> >On Jun 4, 6:00 am, John Larkin > >> >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > >> >> >> >> >> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman > > >> >> >> >> >> <bill.slo...@ieee.org> wrote: > >> >> >> >> >> >On Jun 3, 10:09 pm, Phil Hobbs > >> >> >> >> >> ><pcdhSpamMeSensel...@electrooptical.net> wrote: > >> >> >> >> >> >>BillSlomanwrote: > > >> >> >> >> >> >> > On Jun 3, 9:02 pm, Fred Abse <excretatau...@invalid.i=
nvalid> wrote:
> >> >> >> >> >> >> > > On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote:
<snip>
> >> It would be interesting to consider what sort of computer could be > >> built with early 1950s-sort of technology. Say, a few thousand dual > >> triodes and core memory. > > >Reliability would be an issue. Heated filaments don't last > >forever.Vacuum electronics can't hold a candle to solid-state devices > >when it comes to keeping on working. > > Really? What a brilliant observation. What would s.e.d. do without > you?
It's as nothing compared with your brilliant query about what sort of computer could be built with early 1950's technology. One might wonder why it had to be posted here, rather than directed at the histories of the early 1950's, which talk about the computers which were built with early 1950's technology. http://en.wikipedia.org/wiki/Timeline_of_computing_1950%E2%80%931979 I got to see the remains of CSIRAC in the Physics Department at the University of Melbourne in 1963 - I had to take the Hollerith cards for the Fortran programming course I was doing into that room containing the no-longer working machine, where the cards were picked up and shipped across town every day to the IBM 7040/44 which the University had bought but hadn't then installed on campus. -- Bill Sloman, Nijmegen
Reply by Robert Baer June 7, 20122012-06-07
John Larkin wrote:
> On Wed, 06 Jun 2012 20:09:05 -0800, Robert Baer > <robertbaer@localnet.com> wrote: > >> John Larkin wrote: >>> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT), Bill Sloman >>> <bill.sloman@ieee.org> wrote: >>> >>>> On Jun 5, 4:16 pm, John Larkin >>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >>>>> >>>>> <bill.slo...@ieee.org> wrote: >>>>>> On Jun 4, 6:31 pm, John Larkin >>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >>>>> >>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>> On Jun 4, 4:09 pm, John Larkin >>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >>>>> >>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>> On Jun 4, 6:00 am, John Larkin >>>>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>>> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >>>>> >>>>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>>>> On Jun 3, 10:09 pm, Phil Hobbs >>>>>>>>>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>>>>>>>>>> BillSlomanwrote: >>>>> >>>>>>>>>>>>>> On Jun 3, 9:02 pm, Fred Abse<excretatau...@invalid.invalid> wrote: >>>>>>>>>>>>>>> On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >>>>>>>>>>>>>>>> We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >>>>>>>>>>>>>>>> gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >>>>>>>>>>>>>>>> root turn by grinding back the centre pillar by 0.4mm, >>>>> >>>>>>>>>>>>>>> I think that should be "per turn squared". >>>>> >>>>>>>>>>>>>> Wrong. Inductance is proportional to the square of the number of >>>>>>>>>>>>>> turns, as long as they are closely coupled. >>>>> >>>>>>>>>>>>>> http://en.wikipedia.org/wiki/Inductor >>>>> >>>>>>>>>>>>> If L = alpha * N**2, then alpha has units of henries per turn squared. >>>>>>>>>>>>> (Of course a turn isn't really a unit, just as a radian and a steradian >>>>>>>>>>>>> aren't, but it sure isn't per square root turn.) >>>>> >>>>>>>>>>>> Applying dimensional analysis to a manufacturer's design fudge factor >>>>>>>>>>>> is the sort of thing that physicists do. >>>>> >>>>>>>>>>> Engineers, too. My first engineering course at Tulane, first semister >>>>>>>>>>> freshman year, was an introduction to units and dimensional analysis. >>>>>>>>>>> It was taught by Dr Johnson, the Dean of the Engineering School, who >>>>>>>>>>> thought it was important. >>>>> >>>>>>>>>>> Random noise increases as the square root of bandwidth, so we specify >>>>>>>>>>> it as volts per root Hz. >>>>> >>>>>>>>>>> Inductance increases with turns squared, so we spec a core Al as >>>>>>>>>>> henries per turn squared. >>>>> >>>>>>>>>>> See the difference? >>>>> >>>>>>>>>> It's 9:30am and my brain is working again, so yes - I do. >>>>> >>>>>>>>> Did you PWBC, post without benefit of coffee? I'm doing that now, and >>>>>>>>> it's a great hazard. >>>>> >>>>>>>>>>>> It's not a particularly useful activity. Reminding junior engineers at >>>>>>>>>>>> every possible opportunity that inductance is proportional to the >>>>>>>>>>>> square of the number of turns in a winding is an extremely useful >>>>>>>>>>>> activity, and saves loads of time at design reviews. >>>>> >>>>>>>>>>> They were probably polite enough to laugh at you after you left the >>>>>>>>>>> room. >>>>> >>>>>>>>>> Perhaps. But they'd got the point - attention-getting devices don't >>>>>>>>>> have to be pedantically correct to work. Look at Howard Johnson on >>>>>>>>>> high speed signal propagation. >>>>> >>>>>>>>> He's as dangerous as Professor Moriarty. >>>>> >>>>>>>> I don't know about dangerous, but pedagogically horrible. If you >>>>>>>> compare the lucid exposition of practical physics you get in Ralph >>>>>>>> Morrison's "Grounding and Shielding Techniques in Instrumentation" >>>>> >>>>>>>> http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >>>>> >>>>>>>> with the incoherent messes that Howard Johnson peddles,you go from the >>>>>>>> sublime to the despicable. >>>>> >>>>>>> Yup. It's painful to read, even in the parts where he's technically >>>>>>> correct. >>>>> >>>>>>>>> (Incidentally, the latest "Sherlock" was stunning.) >>>>> >>>>>>>> You mean the BBC televison series? We've been watching it here - we >>>>>>>> get BBC 1 and 2 on the local cable - and liked it a lot. >>>>> >>>>>>> There are two running here now. The "classic" with Jeremy Brett, >>>>>>> pretty good, and the modern-day one. It's the new one that I was >>>>>>> referring to. I read all the Sherlocks several times when I was a kid, >>>>>>> and revisit them now and then for a quick read. >>>>> >>>>>> That makes you a Holmesian, rather than a Sherlock fan. I've just re- >>>>>> read Julina Barnes' "Arthur and George" >>>>> >>>>>> http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >>>>> >>>>>> which is essentially a portrait of Arthur Conan Doyle - a second rate >>>>>> author, who didn't recognise Holmes as his greatest creation. >>>>> >>>>> He claimed to have written one story during a break in a cricket game, >>>>> and killed him off because he was bored with him. >>>>> >>>>>> David Lodge does the English author biography a whole lot better. >>>>>> "Author, Author" about Henry James, and "A Man of Parts" about >>>>>> H.G.Wells, are both substantially better, perhaps because the subjects >>>>>> had a bit more to offer. >>>>> >>>>> I can't read either of them, for some reason. HJ is especially boring >>>>> to me... >>>> >>>> I can't read his novels - nothing ever happens. He wrote a few science- >>>> fiction short stories in the sytle of H.G.Wells (who was a friend of >>>> his) which aren't too bad. >>>> >>>> H.G.Wells was also a second rate novelist. His science fiction is >>>> interesting - the ideas are sufficiently interesting to transcend his >>>> defects as a novelist - if somewhat half-baked. His ideas about the >>>> shape of things to come weren't all that accurate, but his expectation >>>> that technological innovation would change the way we live was useful. >>>> >>>>> I've never made it halfway through any of his books. But I >>>>> can, and do, reread the better Jane Austens and PG Wodehouses >>>>> regularly. >>>> >>>> Jane Austen is well worth rereading. P G Wodehouse isn't - anything >>>> that Wodehouse could do, Terry Pratchett can do better. Terry >>>> Pratchett is a lot better educated than Wodehouse was, and it shows. >>>> >>>>> I'm now reading Enigma, the Turing biography. It's amazing the ideas >>>>> that they had about computers in about 1950. >>>> >>>> Read old copies of Astounding Science Fiction - around 1950 - for >>>> really bizarre ideas about computers. >>> >>> >>> I have "IBM's Early Computers" and some stuff like that. The current >>> concept of a base-2 synchronous-state-machine Von Neumann architecture >>> seems so obvious now, but it sure wasn't in the early days. At least >>> Turing appreciated that binary-decimal conversion could be done in >>> software. >>> >>> Maybe we should have stuck with the Harvard architecture. Microsoft >>> has never learned the difference between code and data. >>> >>> It would be interesting to consider what sort of computer could be >>> built with early 1950s-sort of technology. Say, a few thousand dual >>> triodes and core memory. >>> >>> >> Check! >> And there are ways to extend the life in the region of an order of >> magnitude so that a tube hopper would not be sorely needed. > > Tube computers were reliable enough to be useful. One trick was to run > midnight "margin tests" (run test code with varying filament and B+ > supplies) to weed out the weak tubes. > > But, having read up a bit on early computer architectures, it would > just be interesting to design a computer with just dual triodes. The > HP9100 programmable calculator only had about 20 flipflops, discrete > transistor potted SIP things, and a CRT display. Early PDP8's used > discrete logic board, like a flipflop or a gate, with transistors and > diodes. Those sorts of architectures could have been done easily with > tubes. What was lacking in the 1950s was the concepts. > >
Dual triode..makes me think of the classical 6SN7..tho for slightly less space, 12AU7, 12AT7 or 12AX7 (any one or mix them as the mu is not relevant with a decent FF design). Or for even less space, a pair of nuvistors may do..
Reply by John Larkin June 7, 20122012-06-07
On Wed, 06 Jun 2012 20:09:05 -0800, Robert Baer
<robertbaer@localnet.com> wrote:

>John Larkin wrote: >> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT), Bill Sloman >> <bill.sloman@ieee.org> wrote: >> >>> On Jun 5, 4:16 pm, John Larkin >>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >>>> >>>> <bill.slo...@ieee.org> wrote: >>>>> On Jun 4, 6:31 pm, John Larkin >>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >>>> >>>>>> <bill.slo...@ieee.org> wrote: >>>>>>> On Jun 4, 4:09 pm, John Larkin >>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >>>> >>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>> On Jun 4, 6:00 am, John Larkin >>>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >>>> >>>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>>> On Jun 3, 10:09 pm, Phil Hobbs >>>>>>>>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>>>>>>>>> BillSlomanwrote: >>>> >>>>>>>>>>>>> On Jun 3, 9:02 pm, Fred Abse<excretatau...@invalid.invalid> wrote: >>>>>>>>>>>>>> On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >>>>>>>>>>>>>>> We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >>>>>>>>>>>>>>> gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >>>>>>>>>>>>>>> root turn by grinding back the centre pillar by 0.4mm, >>>> >>>>>>>>>>>>>> I think that should be "per turn squared". >>>> >>>>>>>>>>>>> Wrong. Inductance is proportional to the square of the number of >>>>>>>>>>>>> turns, as long as they are closely coupled. >>>> >>>>>>>>>>>>> http://en.wikipedia.org/wiki/Inductor >>>> >>>>>>>>>>>> If L = alpha * N**2, then alpha has units of henries per turn squared. >>>>>>>>>>>> (Of course a turn isn't really a unit, just as a radian and a steradian >>>>>>>>>>>> aren't, but it sure isn't per square root turn.) >>>> >>>>>>>>>>> Applying dimensional analysis to a manufacturer's design fudge factor >>>>>>>>>>> is the sort of thing that physicists do. >>>> >>>>>>>>>> Engineers, too. My first engineering course at Tulane, first semister >>>>>>>>>> freshman year, was an introduction to units and dimensional analysis. >>>>>>>>>> It was taught by Dr Johnson, the Dean of the Engineering School, who >>>>>>>>>> thought it was important. >>>> >>>>>>>>>> Random noise increases as the square root of bandwidth, so we specify >>>>>>>>>> it as volts per root Hz. >>>> >>>>>>>>>> Inductance increases with turns squared, so we spec a core Al as >>>>>>>>>> henries per turn squared. >>>> >>>>>>>>>> See the difference? >>>> >>>>>>>>> It's 9:30am and my brain is working again, so yes - I do. >>>> >>>>>>>> Did you PWBC, post without benefit of coffee? I'm doing that now, and >>>>>>>> it's a great hazard. >>>> >>>>>>>>>>> It's not a particularly useful activity. Reminding junior engineers at >>>>>>>>>>> every possible opportunity that inductance is proportional to the >>>>>>>>>>> square of the number of turns in a winding is an extremely useful >>>>>>>>>>> activity, and saves loads of time at design reviews. >>>> >>>>>>>>>> They were probably polite enough to laugh at you after you left the >>>>>>>>>> room. >>>> >>>>>>>>> Perhaps. But they'd got the point - attention-getting devices don't >>>>>>>>> have to be pedantically correct to work. Look at Howard Johnson on >>>>>>>>> high speed signal propagation. >>>> >>>>>>>> He's as dangerous as Professor Moriarty. >>>> >>>>>>> I don't know about dangerous, but pedagogically horrible. If you >>>>>>> compare the lucid exposition of practical physics you get in Ralph >>>>>>> Morrison's "Grounding and Shielding Techniques in Instrumentation" >>>> >>>>>>> http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >>>> >>>>>>> with the incoherent messes that Howard Johnson peddles,you go from the >>>>>>> sublime to the despicable. >>>> >>>>>> Yup. It's painful to read, even in the parts where he's technically >>>>>> correct. >>>> >>>>>>>> (Incidentally, the latest "Sherlock" was stunning.) >>>> >>>>>>> You mean the BBC televison series? We've been watching it here - we >>>>>>> get BBC 1 and 2 on the local cable - and liked it a lot. >>>> >>>>>> There are two running here now. The "classic" with Jeremy Brett, >>>>>> pretty good, and the modern-day one. It's the new one that I was >>>>>> referring to. I read all the Sherlocks several times when I was a kid, >>>>>> and revisit them now and then for a quick read. >>>> >>>>> That makes you a Holmesian, rather than a Sherlock fan. I've just re- >>>>> read Julina Barnes' "Arthur and George" >>>> >>>>> http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >>>> >>>>> which is essentially a portrait of Arthur Conan Doyle - a second rate >>>>> author, who didn't recognise Holmes as his greatest creation. >>>> >>>> He claimed to have written one story during a break in a cricket game, >>>> and killed him off because he was bored with him. >>>> >>>>> David Lodge does the English author biography a whole lot better. >>>>> "Author, Author" about Henry James, and "A Man of Parts" about >>>>> H.G.Wells, are both substantially better, perhaps because the subjects >>>>> had a bit more to offer. >>>> >>>> I can't read either of them, for some reason. HJ is especially boring >>>> to me... >>> >>> I can't read his novels - nothing ever happens. He wrote a few science- >>> fiction short stories in the sytle of H.G.Wells (who was a friend of >>> his) which aren't too bad. >>> >>> H.G.Wells was also a second rate novelist. His science fiction is >>> interesting - the ideas are sufficiently interesting to transcend his >>> defects as a novelist - if somewhat half-baked. His ideas about the >>> shape of things to come weren't all that accurate, but his expectation >>> that technological innovation would change the way we live was useful. >>> >>>> I've never made it halfway through any of his books. But I >>>> can, and do, reread the better Jane Austens and PG Wodehouses >>>> regularly. >>> >>> Jane Austen is well worth rereading. P G Wodehouse isn't - anything >>> that Wodehouse could do, Terry Pratchett can do better. Terry >>> Pratchett is a lot better educated than Wodehouse was, and it shows. >>> >>>> I'm now reading Enigma, the Turing biography. It's amazing the ideas >>>> that they had about computers in about 1950. >>> >>> Read old copies of Astounding Science Fiction - around 1950 - for >>> really bizarre ideas about computers. >> >> >> I have "IBM's Early Computers" and some stuff like that. The current >> concept of a base-2 synchronous-state-machine Von Neumann architecture >> seems so obvious now, but it sure wasn't in the early days. At least >> Turing appreciated that binary-decimal conversion could be done in >> software. >> >> Maybe we should have stuck with the Harvard architecture. Microsoft >> has never learned the difference between code and data. >> >> It would be interesting to consider what sort of computer could be >> built with early 1950s-sort of technology. Say, a few thousand dual >> triodes and core memory. >> >> > Check! > And there are ways to extend the life in the region of an order of >magnitude so that a tube hopper would not be sorely needed.
Tube computers were reliable enough to be useful. One trick was to run midnight "margin tests" (run test code with varying filament and B+ supplies) to weed out the weak tubes. But, having read up a bit on early computer architectures, it would just be interesting to design a computer with just dual triodes. The HP9100 programmable calculator only had about 20 flipflops, discrete transistor potted SIP things, and a CRT display. Early PDP8's used discrete logic board, like a flipflop or a gate, with transistors and diodes. Those sorts of architectures could have been done easily with tubes. What was lacking in the 1950s was the concepts. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by John Larkin June 7, 20122012-06-07
On Tue, 5 Jun 2012 10:13:08 -0700 (PDT), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jun 5, 5:55&#2013266080;pm, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >On Jun 5, 4:16 pm, John Larkin >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >> >> >> <bill.slo...@ieee.org> wrote: >> >> >On Jun 4, 6:31 pm, John Larkin >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >On Jun 4, 4:09 pm, John Larkin >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >> >On Jun 4, 6:00 am, John Larkin >> >> >> >> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> >> >> >> >> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >> >> >> >> >> >On Jun 3, 10:09 pm, Phil Hobbs >> >> >> >> >> ><pcdhSpamMeSensel...@electrooptical.net> wrote: >> >> >> >> >> >>BillSlomanwrote: >> >> >> >> >> >> >> > On Jun 3, 9:02 pm, Fred Abse <excretatau...@invalid.invalid> wrote: >> >> >> >> >> >> > > On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >> >> >> >> >> >> > > > We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >> >> >> >> >> >> > > > gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >> >> >> >> >> >> > > > root turn by grinding back the centre pillar by 0.4mm, >> >> >> >> >> >> >> > > I think that should be "per turn squared". >> >> >> >> >> >> >> > Wrong. Inductance is proportional to the square of the number of >> >> >> >> >> >> > turns, as long as they are closely coupled. >> >> >> >> >> >> >> >http://en.wikipedia.org/wiki/Inductor >> >> >> >> >> >> >> If L = alpha * N**2, then alpha has units of henries per turn squared. >> >> >> >> >> >> (Of course a turn isn't really a unit, just as a radian and a steradian >> >> >> >> >> >> aren't, but it sure isn't per square root turn.) >> >> >> >> >> >> >Applying dimensional analysis to a manufacturer's design fudge factor >> >> >> >> >> >is the sort of thing that physicists do. >> >> >> >> >> >> Engineers, too. My first engineering course at Tulane, first semister >> >> >> >> >> freshman year, was an introduction to units and dimensional analysis. >> >> >> >> >> It was taught by Dr Johnson, the Dean of the Engineering School, who >> >> >> >> >> thought it was important. >> >> >> >> >> >> Random noise increases as the square root of bandwidth, so we specify >> >> >> >> >> it as volts per root Hz. >> >> >> >> >> >> Inductance increases with turns squared, so we spec a core Al as >> >> >> >> >> henries per turn squared. >> >> >> >> >> >> See the difference? >> >> >> >> >> >It's 9:30am and my brain is working again, so yes - I do. >> >> >> >> >> Did you PWBC, post without benefit of coffee? I'm doing that now, and >> >> >> >> it's a great hazard. >> >> >> >> >> >> >It's not a particularly useful activity. Reminding junior engineers at >> >> >> >> >> >every possible opportunity that inductance is proportional to the >> >> >> >> >> >square of the number of turns in a winding is an extremely useful >> >> >> >> >> >activity, and saves loads of time at design reviews. >> >> >> >> >> >> They were probably polite enough to laugh at you after you left the >> >> >> >> >> room. >> >> >> >> >> >Perhaps. But they'd got the point - attention-getting devices don't >> >> >> >> >have to be pedantically correct to work. Look at Howard Johnson on >> >> >> >> >high speed signal propagation. >> >> >> >> >> He's as dangerous as Professor Moriarty. >> >> >> >> >I don't know about dangerous, but pedagogically horrible. If you >> >> >> >compare the lucid exposition of practical physics you get in Ralph >> >> >> >Morrison's "Grounding and Shielding Techniques in Instrumentation" >> >> >> >> >http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >> >> >> >> >with the incoherent messes that Howard Johnson peddles,you go from the >> >> >> >sublime to the despicable. >> >> >> >> Yup. It's painful to read, even in the parts where he's technically >> >> >> correct. >> >> >> >> >> (Incidentally, the latest "Sherlock" was stunning.) >> >> >> >> >You mean the BBC televison series? We've been watching it here - we >> >> >> >get BBC 1 and 2 on the local cable - and liked it a lot. >> >> >> >> There are two running here now. The "classic" with Jeremy Brett, >> >> >> pretty good, and the modern-day one. It's the new one that I was >> >> >> referring to. I read all the Sherlocks several times when I was a kid, >> >> >> and revisit them now and then for a quick read. >> >> >> >That makes you a Holmesian, rather than a Sherlock fan. I've just re- >> >> >read Julina Barnes' "Arthur and George" >> >> >> >http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >> >> >> >which is essentially a portrait of Arthur Conan Doyle - a second rate >> >> >author, who didn't recognise Holmes as his greatest creation. >> >> >> He claimed to have written one story during a break in a cricket game, >> >> and killed him off because he was bored with him. >> >> >> >David Lodge does the English author biography a whole lot better. >> >> >"Author, Author" about Henry James, and "A Man of Parts" about >> >> >H.G.Wells, are both substantially better, perhaps because the subjects >> >> >had a bit more to offer. >> >> >> I can't read either of them, for some reason. HJ is especially boring >> >> to me... >> >> >I can't read his novels - nothing ever happens. He wrote a few science- >> >fiction short stories in the sytle of H.G.Wells (who was a friend of >> >his) which aren't too bad. >> >> >H.G.Wells was also a second rate novelist. His science fiction is >> >interesting - the ideas are sufficiently interesting to transcend his >> >defects as a novelist - if somewhat half-baked. His ideas about the >> >shape of things to come weren't all that accurate, but his expectation >> >that technological innovation would change the way we live was useful. >> >> >> I've never made it halfway through any of his books. But I >> >> can, and do, reread the better Jane Austens and PG Wodehouses >> >> regularly. >> >> >Jane Austen is well worth rereading. P G Wodehouse isn't - anything >> >that Wodehouse could do, Terry Pratchett can do better. Terry >> >Pratchett is a lot better educated than Wodehouse was, and it shows. >> >> >> I'm now reading Enigma, the Turing biography. It's amazing the ideas >> >> that they had about computers in about 1950. >> >> >Read old copies of Astounding Science Fiction - around 1950 - for >> >really bizarre ideas about computers. >> >> I have "IBM's Early Computers" and some stuff like that. The current >> concept of a base-2 synchronous-state-machine Von Neumann architecture >> seems so obvious now, but it sure wasn't in the early days. At least >> Turing appreciated that binary-decimal conversion could be done in >> software. >> >> Maybe we should have stuck with the Harvard architecture. > >Most signal-processing chips seem to use it > >> Microsoft >> has never learned the difference between code and data. > >Turing pointed out that there's no fundamental difference. I quite >liked self-modifying code, and used it in my 1968 PDP-8 program. > >> It would be interesting to consider what sort of computer could be >> built with early 1950s-sort of technology. Say, a few thousand dual >> triodes and core memory. > >Reliability would be an issue. Heated filaments don't last >forever.Vacuum electronics can't hold a candle to solid-state devices >when it comes to keeping on working.
Really? What a brilliant observation. What would s.e.d. do without you? -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by Robert Baer June 7, 20122012-06-07
Bill Sloman wrote:
> On Jun 5, 5:55 pm, John Larkin > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT),BillSloman >> >> >> >> >> >> >> >> >> >> <bill.slo...@ieee.org> wrote: >>> On Jun 5, 4:16 pm, John Larkin >>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >> >>>> <bill.slo...@ieee.org> wrote: >>>>> On Jun 4, 6:31 pm, John Larkin >>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >> >>>>>> <bill.slo...@ieee.org> wrote: >>>>>>> On Jun 4, 4:09 pm, John Larkin >>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >> >>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>> On Jun 4, 6:00 am, John Larkin >>>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >> >>>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>>> On Jun 3, 10:09 pm, Phil Hobbs >>>>>>>>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>>>>>>>>> BillSlomanwrote: >> >>>>>>>>>>>>> On Jun 3, 9:02 pm, Fred Abse<excretatau...@invalid.invalid> wrote: >>>>>>>>>>>>>> On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >>>>>>>>>>>>>>> We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >>>>>>>>>>>>>>> gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >>>>>>>>>>>>>>> root turn by grinding back the centre pillar by 0.4mm, >> >>>>>>>>>>>>>> I think that should be "per turn squared". >> >>>>>>>>>>>>> Wrong. Inductance is proportional to the square of the number of >>>>>>>>>>>>> turns, as long as they are closely coupled. >> >>>>>>>>>>>>> http://en.wikipedia.org/wiki/Inductor >> >>>>>>>>>>>> If L = alpha * N**2, then alpha has units of henries per turn squared. >>>>>>>>>>>> (Of course a turn isn't really a unit, just as a radian and a steradian >>>>>>>>>>>> aren't, but it sure isn't per square root turn.) >> >>>>>>>>>>> Applying dimensional analysis to a manufacturer's design fudge factor >>>>>>>>>>> is the sort of thing that physicists do. >> >>>>>>>>>> Engineers, too. My first engineering course at Tulane, first semister >>>>>>>>>> freshman year, was an introduction to units and dimensional analysis. >>>>>>>>>> It was taught by Dr Johnson, the Dean of the Engineering School, who >>>>>>>>>> thought it was important. >> >>>>>>>>>> Random noise increases as the square root of bandwidth, so we specify >>>>>>>>>> it as volts per root Hz. >> >>>>>>>>>> Inductance increases with turns squared, so we spec a core Al as >>>>>>>>>> henries per turn squared. >> >>>>>>>>>> See the difference? >> >>>>>>>>> It's 9:30am and my brain is working again, so yes - I do. >> >>>>>>>> Did you PWBC, post without benefit of coffee? I'm doing that now, and >>>>>>>> it's a great hazard. >> >>>>>>>>>>> It's not a particularly useful activity. Reminding junior engineers at >>>>>>>>>>> every possible opportunity that inductance is proportional to the >>>>>>>>>>> square of the number of turns in a winding is an extremely useful >>>>>>>>>>> activity, and saves loads of time at design reviews. >> >>>>>>>>>> They were probably polite enough to laugh at you after you left the >>>>>>>>>> room. >> >>>>>>>>> Perhaps. But they'd got the point - attention-getting devices don't >>>>>>>>> have to be pedantically correct to work. Look at Howard Johnson on >>>>>>>>> high speed signal propagation. >> >>>>>>>> He's as dangerous as Professor Moriarty. >> >>>>>>> I don't know about dangerous, but pedagogically horrible. If you >>>>>>> compare the lucid exposition of practical physics you get in Ralph >>>>>>> Morrison's "Grounding and Shielding Techniques in Instrumentation" >> >>>>>>> http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >> >>>>>>> with the incoherent messes that Howard Johnson peddles,you go from the >>>>>>> sublime to the despicable. >> >>>>>> Yup. It's painful to read, even in the parts where he's technically >>>>>> correct. >> >>>>>>>> (Incidentally, the latest "Sherlock" was stunning.) >> >>>>>>> You mean the BBC televison series? We've been watching it here - we >>>>>>> get BBC 1 and 2 on the local cable - and liked it a lot. >> >>>>>> There are two running here now. The "classic" with Jeremy Brett, >>>>>> pretty good, and the modern-day one. It's the new one that I was >>>>>> referring to. I read all the Sherlocks several times when I was a kid, >>>>>> and revisit them now and then for a quick read. >> >>>>> That makes you a Holmesian, rather than a Sherlock fan. I've just re- >>>>> read Julina Barnes' "Arthur and George" >> >>>>> http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >> >>>>> which is essentially a portrait of Arthur Conan Doyle - a second rate >>>>> author, who didn't recognise Holmes as his greatest creation. >> >>>> He claimed to have written one story during a break in a cricket game, >>>> and killed him off because he was bored with him. >> >>>>> David Lodge does the English author biography a whole lot better. >>>>> "Author, Author" about Henry James, and "A Man of Parts" about >>>>> H.G.Wells, are both substantially better, perhaps because the subjects >>>>> had a bit more to offer. >> >>>> I can't read either of them, for some reason. HJ is especially boring >>>> to me... >> >>> I can't read his novels - nothing ever happens. He wrote a few science- >>> fiction short stories in the sytle of H.G.Wells (who was a friend of >>> his) which aren't too bad. >> >>> H.G.Wells was also a second rate novelist. His science fiction is >>> interesting - the ideas are sufficiently interesting to transcend his >>> defects as a novelist - if somewhat half-baked. His ideas about the >>> shape of things to come weren't all that accurate, but his expectation >>> that technological innovation would change the way we live was useful. >> >>>> I've never made it halfway through any of his books. But I >>>> can, and do, reread the better Jane Austens and PG Wodehouses >>>> regularly. >> >>> Jane Austen is well worth rereading. P G Wodehouse isn't - anything >>> that Wodehouse could do, Terry Pratchett can do better. Terry >>> Pratchett is a lot better educated than Wodehouse was, and it shows. >> >>>> I'm now reading Enigma, the Turing biography. It's amazing the ideas >>>> that they had about computers in about 1950. >> >>> Read old copies of Astounding Science Fiction - around 1950 - for >>> really bizarre ideas about computers. >> >> I have "IBM's Early Computers" and some stuff like that. The current >> concept of a base-2 synchronous-state-machine Von Neumann architecture >> seems so obvious now, but it sure wasn't in the early days. At least >> Turing appreciated that binary-decimal conversion could be done in >> software. >> >> Maybe we should have stuck with the Harvard architecture. > > Most signal-processing chips seem to use it > >> Microsoft >> has never learned the difference between code and data. > > Turing pointed out that there's no fundamental difference. I quite > liked self-modifying code, and used it in my 1968 PDP-8 program. > >> It would be interesting to consider what sort of computer could be >> built with early 1950s-sort of technology. Say, a few thousand dual >> triodes and core memory. > > Reliability would be an issue. Heated filaments don't last > forever.Vacuum electronics can't hold a candle to solid-state devices > when it comes to keeping on working. > > -- > Bill Sloman, Nijmegen >
..then try using 6.3VAC on a semiconductor device - or B+ for that matter.. Tubes can resist B+ on any electrode, and due to current limiting on(small) supplies even the filament may resist B+.. Oh,do not forget RFI swamping out semiconductors - making them multi-legged resistors. Thresholds in tubes are about an order of magnitude better..
Reply by Robert Baer June 7, 20122012-06-07
John Larkin wrote:
> On Tue, 5 Jun 2012 10:13:08 -0700 (PDT), Bill Sloman > <bill.sloman@ieee.org> wrote: > >> On Jun 5, 5:55 pm, John Larkin >> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT),BillSloman >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> <bill.slo...@ieee.org> wrote: >>>> On Jun 5, 4:16 pm, John Larkin >>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >>> >>>>> <bill.slo...@ieee.org> wrote: >>>>>> On Jun 4, 6:31 pm, John Larkin >>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >>> >>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>> On Jun 4, 4:09 pm, John Larkin >>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >>> >>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>> On Jun 4, 6:00 am, John Larkin >>>>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>>> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >>> >>>>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>>>> On Jun 3, 10:09 pm, Phil Hobbs >>>>>>>>>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>>>>>>>>>> BillSlomanwrote: >>> >>>>>>>>>>>>>> On Jun 3, 9:02 pm, Fred Abse<excretatau...@invalid.invalid> wrote: >>>>>>>>>>>>>>> On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >>>>>>>>>>>>>>>> We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >>>>>>>>>>>>>>>> gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >>>>>>>>>>>>>>>> root turn by grinding back the centre pillar by 0.4mm, >>> >>>>>>>>>>>>>>> I think that should be "per turn squared". >>> >>>>>>>>>>>>>> Wrong. Inductance is proportional to the square of the number of >>>>>>>>>>>>>> turns, as long as they are closely coupled. >>> >>>>>>>>>>>>>> http://en.wikipedia.org/wiki/Inductor >>> >>>>>>>>>>>>> If L = alpha * N**2, then alpha has units of henries per turn squared. >>>>>>>>>>>>> (Of course a turn isn't really a unit, just as a radian and a steradian >>>>>>>>>>>>> aren't, but it sure isn't per square root turn.) >>> >>>>>>>>>>>> Applying dimensional analysis to a manufacturer's design fudge factor >>>>>>>>>>>> is the sort of thing that physicists do. >>> >>>>>>>>>>> Engineers, too. My first engineering course at Tulane, first semister >>>>>>>>>>> freshman year, was an introduction to units and dimensional analysis. >>>>>>>>>>> It was taught by Dr Johnson, the Dean of the Engineering School, who >>>>>>>>>>> thought it was important. >>> >>>>>>>>>>> Random noise increases as the square root of bandwidth, so we specify >>>>>>>>>>> it as volts per root Hz. >>> >>>>>>>>>>> Inductance increases with turns squared, so we spec a core Al as >>>>>>>>>>> henries per turn squared. >>> >>>>>>>>>>> See the difference? >>> >>>>>>>>>> It's 9:30am and my brain is working again, so yes - I do. >>> >>>>>>>>> Did you PWBC, post without benefit of coffee? I'm doing that now, and >>>>>>>>> it's a great hazard. >>> >>>>>>>>>>>> It's not a particularly useful activity. Reminding junior engineers at >>>>>>>>>>>> every possible opportunity that inductance is proportional to the >>>>>>>>>>>> square of the number of turns in a winding is an extremely useful >>>>>>>>>>>> activity, and saves loads of time at design reviews. >>> >>>>>>>>>>> They were probably polite enough to laugh at you after you left the >>>>>>>>>>> room. >>> >>>>>>>>>> Perhaps. But they'd got the point - attention-getting devices don't >>>>>>>>>> have to be pedantically correct to work. Look at Howard Johnson on >>>>>>>>>> high speed signal propagation. >>> >>>>>>>>> He's as dangerous as Professor Moriarty. >>> >>>>>>>> I don't know about dangerous, but pedagogically horrible. If you >>>>>>>> compare the lucid exposition of practical physics you get in Ralph >>>>>>>> Morrison's "Grounding and Shielding Techniques in Instrumentation" >>> >>>>>>>> http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >>> >>>>>>>> with the incoherent messes that Howard Johnson peddles,you go from the >>>>>>>> sublime to the despicable. >>> >>>>>>> Yup. It's painful to read, even in the parts where he's technically >>>>>>> correct. >>> >>>>>>>>> (Incidentally, the latest "Sherlock" was stunning.) >>> >>>>>>>> You mean the BBC televison series? We've been watching it here - we >>>>>>>> get BBC 1 and 2 on the local cable - and liked it a lot. >>> >>>>>>> There are two running here now. The "classic" with Jeremy Brett, >>>>>>> pretty good, and the modern-day one. It's the new one that I was >>>>>>> referring to. I read all the Sherlocks several times when I was a kid, >>>>>>> and revisit them now and then for a quick read. >>> >>>>>> That makes you a Holmesian, rather than a Sherlock fan. I've just re- >>>>>> read Julina Barnes' "Arthur and George" >>> >>>>>> http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >>> >>>>>> which is essentially a portrait of Arthur Conan Doyle - a second rate >>>>>> author, who didn't recognise Holmes as his greatest creation. >>> >>>>> He claimed to have written one story during a break in a cricket game, >>>>> and killed him off because he was bored with him. >>> >>>>>> David Lodge does the English author biography a whole lot better. >>>>>> "Author, Author" about Henry James, and "A Man of Parts" about >>>>>> H.G.Wells, are both substantially better, perhaps because the subjects >>>>>> had a bit more to offer. >>> >>>>> I can't read either of them, for some reason. HJ is especially boring >>>>> to me... >>> >>>> I can't read his novels - nothing ever happens. He wrote a few science- >>>> fiction short stories in the sytle of H.G.Wells (who was a friend of >>>> his) which aren't too bad. >>> >>>> H.G.Wells was also a second rate novelist. His science fiction is >>>> interesting - the ideas are sufficiently interesting to transcend his >>>> defects as a novelist - if somewhat half-baked. His ideas about the >>>> shape of things to come weren't all that accurate, but his expectation >>>> that technological innovation would change the way we live was useful. >>> >>>>> I've never made it halfway through any of his books. But I >>>>> can, and do, reread the better Jane Austens and PG Wodehouses >>>>> regularly. >>> >>>> Jane Austen is well worth rereading. P G Wodehouse isn't - anything >>>> that Wodehouse could do, Terry Pratchett can do better. Terry >>>> Pratchett is a lot better educated than Wodehouse was, and it shows. >>> >>>>> I'm now reading Enigma, the Turing biography. It's amazing the ideas >>>>> that they had about computers in about 1950. >>> >>>> Read old copies of Astounding Science Fiction - around 1950 - for >>>> really bizarre ideas about computers. >>> >>> I have "IBM's Early Computers" and some stuff like that. The current >>> concept of a base-2 synchronous-state-machine Von Neumann architecture >>> seems so obvious now, but it sure wasn't in the early days. At least >>> Turing appreciated that binary-decimal conversion could be done in >>> software. >>> >>> Maybe we should have stuck with the Harvard architecture. >> >> Most signal-processing chips seem to use it >> >>> Microsoft >>> has never learned the difference between code and data. >> >> Turing pointed out that there's no fundamental difference. I quite >> liked self-modifying code, and used it in my 1968 PDP-8 program. >> > > Modern CPUs with MMUs can separate executable code from stacks and > data; modern C compilers and OSs just don't bother much to use the > facilities. That's why we have so many stack and buffer overflow > trojans. > >
..not to mention memory "leaks" which would be impossible with correct coding..
Reply by Robert Baer June 7, 20122012-06-07
John Larkin wrote:
> On Tue, 5 Jun 2012 07:48:12 -0700 (PDT), Bill Sloman > <bill.sloman@ieee.org> wrote: > >> On Jun 5, 4:16 pm, John Larkin >> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>> On Mon, 4 Jun 2012 23:09:42 -0700 (PDT),BillSloman >>> >>> <bill.slo...@ieee.org> wrote: >>>> On Jun 4, 6:31 pm, John Larkin >>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>> On Mon, 4 Jun 2012 08:51:29 -0700 (PDT),BillSloman >>> >>>>> <bill.slo...@ieee.org> wrote: >>>>>> On Jun 4, 4:09 pm, John Larkin >>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> On Mon, 4 Jun 2012 00:34:20 -0700 (PDT),BillSloman >>> >>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>> On Jun 4, 6:00 am, John Larkin >>>>>>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>> On Sun, 3 Jun 2012 17:58:36 -0700 (PDT),BillSloman >>> >>>>>>>>> <bill.slo...@ieee.org> wrote: >>>>>>>>>> On Jun 3, 10:09 pm, Phil Hobbs >>>>>>>>>> <pcdhSpamMeSensel...@electrooptical.net> wrote: >>>>>>>>>>> BillSlomanwrote: >>> >>>>>>>>>>>> On Jun 3, 9:02 pm, Fred Abse<excretatau...@invalid.invalid> wrote: >>>>>>>>>>>>> On Sun, 03 Jun 2012 05:11:52 -0700,BillSlomanwrote: >>>>>>>>>>>>>> We've just measured a coupling of 0.98 in a gapped RM14 core - EPCOS >>>>>>>>>>>>>> gapped it down from 6000uH/root turn for an ungapped pair to 630nH per >>>>>>>>>>>>>> root turn by grinding back the centre pillar by 0.4mm, >>> >>>>>>>>>>>>> I think that should be "per turn squared". >>> >>>>>>>>>>>> Wrong. Inductance is proportional to the square of the number of >>>>>>>>>>>> turns, as long as they are closely coupled. >>> >>>>>>>>>>>> http://en.wikipedia.org/wiki/Inductor >>> >>>>>>>>>>> If L = alpha * N**2, then alpha has units of henries per turn squared. >>>>>>>>>>> (Of course a turn isn't really a unit, just as a radian and a steradian >>>>>>>>>>> aren't, but it sure isn't per square root turn.) >>> >>>>>>>>>> Applying dimensional analysis to a manufacturer's design fudge factor >>>>>>>>>> is the sort of thing that physicists do. >>> >>>>>>>>> Engineers, too. My first engineering course at Tulane, first semister >>>>>>>>> freshman year, was an introduction to units and dimensional analysis. >>>>>>>>> It was taught by Dr Johnson, the Dean of the Engineering School, who >>>>>>>>> thought it was important. >>> >>>>>>>>> Random noise increases as the square root of bandwidth, so we specify >>>>>>>>> it as volts per root Hz. >>> >>>>>>>>> Inductance increases with turns squared, so we spec a core Al as >>>>>>>>> henries per turn squared. >>> >>>>>>>>> See the difference? >>> >>>>>>>> It's 9:30am and my brain is working again, so yes - I do. >>> >>>>>>> Did you PWBC, post without benefit of coffee? I'm doing that now, and >>>>>>> it's a great hazard. >>> >>>>>>>>>> It's not a particularly useful activity. Reminding junior engineers at >>>>>>>>>> every possible opportunity that inductance is proportional to the >>>>>>>>>> square of the number of turns in a winding is an extremely useful >>>>>>>>>> activity, and saves loads of time at design reviews. >>> >>>>>>>>> They were probably polite enough to laugh at you after you left the >>>>>>>>> room. >>> >>>>>>>> Perhaps. But they'd got the point - attention-getting devices don't >>>>>>>> have to be pedantically correct to work. Look at Howard Johnson on >>>>>>>> high speed signal propagation. >>> >>>>>>> He's as dangerous as Professor Moriarty. >>> >>>>>> I don't know about dangerous, but pedagogically horrible. If you >>>>>> compare the lucid exposition of practical physics you get in Ralph >>>>>> Morrison's "Grounding and Shielding Techniques in Instrumentation" >>> >>>>>> http://www.amazon.com/Grounding-Shielding-Techniques-Ralph-Morrison/d... >>> >>>>>> with the incoherent messes that Howard Johnson peddles,you go from the >>>>>> sublime to the despicable. >>> >>>>> Yup. It's painful to read, even in the parts where he's technically >>>>> correct. >>> >>>>>>> (Incidentally, the latest "Sherlock" was stunning.) >>> >>>>>> You mean the BBC televison series? We've been watching it here - we >>>>>> get BBC 1 and 2 on the local cable - and liked it a lot. >>> >>>>> There are two running here now. The "classic" with Jeremy Brett, >>>>> pretty good, and the modern-day one. It's the new one that I was >>>>> referring to. I read all the Sherlocks several times when I was a kid, >>>>> and revisit them now and then for a quick read. >>> >>>> That makes you a Holmesian, rather than a Sherlock fan. I've just re- >>>> read Julina Barnes' "Arthur and George" >>> >>>> http://www.guardian.co.uk/books/2005/jun/26/fiction.shopping >>> >>>> which is essentially a portrait of Arthur Conan Doyle - a second rate >>>> author, who didn't recognise Holmes as his greatest creation. >>> >>> He claimed to have written one story during a break in a cricket game, >>> and killed him off because he was bored with him. >>> >>>> David Lodge does the English author biography a whole lot better. >>>> "Author, Author" about Henry James, and "A Man of Parts" about >>>> H.G.Wells, are both substantially better, perhaps because the subjects >>>> had a bit more to offer. >>> >>> I can't read either of them, for some reason. HJ is especially boring >>> to me... >> >> I can't read his novels - nothing ever happens. He wrote a few science- >> fiction short stories in the sytle of H.G.Wells (who was a friend of >> his) which aren't too bad. >> >> H.G.Wells was also a second rate novelist. His science fiction is >> interesting - the ideas are sufficiently interesting to transcend his >> defects as a novelist - if somewhat half-baked. His ideas about the >> shape of things to come weren't all that accurate, but his expectation >> that technological innovation would change the way we live was useful. >> >>> I've never made it halfway through any of his books. But I >>> can, and do, reread the better Jane Austens and PG Wodehouses >>> regularly. >> >> Jane Austen is well worth rereading. P G Wodehouse isn't - anything >> that Wodehouse could do, Terry Pratchett can do better. Terry >> Pratchett is a lot better educated than Wodehouse was, and it shows. >> >>> I'm now reading Enigma, the Turing biography. It's amazing the ideas >>> that they had about computers in about 1950. >> >> Read old copies of Astounding Science Fiction - around 1950 - for >> really bizarre ideas about computers. > > > I have "IBM's Early Computers" and some stuff like that. The current > concept of a base-2 synchronous-state-machine Von Neumann architecture > seems so obvious now, but it sure wasn't in the early days. At least > Turing appreciated that binary-decimal conversion could be done in > software. > > Maybe we should have stuck with the Harvard architecture. Microsoft > has never learned the difference between code and data. > > It would be interesting to consider what sort of computer could be > built with early 1950s-sort of technology. Say, a few thousand dual > triodes and core memory. > >
Check! And there are ways to extend the life in the region of an order of magnitude so that a tube hopper would not be sorely needed.