John Doty wrote: > On May 15, 2009, at 3:10 PM, Joerg wrote: > >> John Doty wrote: >>> On May 15, 2009, at 2:06 PM, Joerg wrote: >>> >>>> John Doty wrote: >> [...] >> >>>> I think the BF862 will be around for a long time, >>> So will the 6L6, but few engineers ever have reason to design with >>> one. >>> >> However, those who do make oodles of money. Audio freaks seem to have >> pockets of infinite depths. > > Sure, but so what? There's no need to train the average EE to do this > work. >
Until they must design a large transmitter or HV gen. Right here, right now, I am working with a tube that is fed almost 100kV. Always one hand in pocket ... >> There's one 6L6 on duty in our living room, inside a Hammond organ. >> The >> sound is amazing although it could be done class-D these days. But not >> back in 1961. > > My bedside radio has a 42 for its output stage, so I've got you beat > there ;-). 1934 Stromberg-Carlson, just the right sound for a ball game. > Cool. But I still got you beat, have a radio with one of these from the mid 20's. At the bottom of the link you can see that this multi-section tube is actually the very first integrated circuit: http://www.radiomuseum-bocket.de/museum/int./english/loewe-3-nf-tube.php So maybe you are right, the first signs that the world might be going towards ICs started in the roaring 20's :-) >> If you need a new 6L6 you can still buy them fresh off the >> belt from places like Sovtek. > > Yeah, but try to find a new 42. Fortunately, tubes that survive their > first few years and aren't stressed too much tend to last a long time. > But don't push your luck. Get a spare while you still can. Else you have to do the unthinkable like I had to with my old Astor BPJ, had to adapt the set so it can take a slightly different IF stage tube. >> >>>> else Digikey wouldn't >>>> keep >10k of them in stock most of the time. The six bump BGA (I >>>> hate >>>> BGAs...) won't ever happen at reasonable cost >>> Doesn't have to be reasonable cost. The Amptek thing everybody uses >>> is $250 apiece, and is too bulky and power hungry for something like >>> an x-ray APD array. If NASA and DARPA ever quit arguing over who >>> should fund XNAV, they have the need, and they have the money. But >>> they're both as bad as Windows users: "We have a common interest so >>> here's what I need you to develop for me for free...". >>> >> Looks like a case of Windows-people phobia :-) > > Not phobia, just an observation. gEDA was created by *nix people. It > is maintained by *nix people. It is extended by *nix people. But > Windows people who wander in here never come to help, to roll up > their sleeves and contribute. They would be welcome if they did. > They can still provide ideas. Some of the features found in Windows-based CAD are pretty cool. >> Cost may not matter in your business but it does when it comes to >> telco >> and other markets. > > That's one of the reasons IC's are taking over. In the high volume > markets they're cheaper than bunches of discretes. > Sure, but in the high power circuits. Apex and similar amps set you back hundreds of Dollars. A pop. The discrete solutions were never above $10. >> Many people tend to immediately default to "ready to >> go" modules such as Apex amps where gusto is required. Part of my >> income >> is related to replacing such designs with discretes, with cost savings >> that regularly stun people. Especially controllers and CFOs ... > > As IC's continue to increase in power, they'll get there. Also, many > power devices these days appear to be discretes, but are IC's inside. > You can't model a "power MOSFET" as a simple discrete, need a > subcircuit. > Some, yes. >> >>>> unless there is a huge >>>> consumer app that needs it. Some laser measurement device or >>>> whatever. >>>> >>>> As for smaller geometry JFETs, those unfortunately do tend to >>>> vanish and >>>> someday we might even read a eulogy on ye olde 2SK3372 :-( >>> The handwriting is on the wall. >>> >> Not yet. The -G version is in mass production and Digikey still has >> tons >> in stock. If it ever goes lalaland it'll become hard to make >> micropower >> oscillators that can live off fractions of a volt. Chips don't do that >> well down there. > > They keep getting better. Especially for micropower low voltage > cases. And they've been used in such applications in watches for years. > Same for hearing aids. The Japanese were always good in those domains. But when Vbat get down to 600-700mV they usually quit. A fuel cell doesn't have more than that and you've got to start the electronics somehow. > I remember this same argument over tubes. And while the haven't > exactly gone away (the reheated cup of tea in my hand is proof!) they > have been sufficiently eclipsed that for the purposes of a university > professor designing an EE curriculum they may safely be ignored. > Discrete semiconductors have the same future, but there is less here > than you think. Future designers will still have to design with > individual transistors, but they'll mostly fiddle with w, l, and m > (or whatever equivalent their HDL uses) to get them. Anybody who can > analyze the consequences of those choices can easily learn to use > discretes in the rare cases where they will be necessary. But they'll > be annoyed by the limited choices. ASIC design has spoiled me enough, > I'm already there. > Students that only learn device geometries and such can be great engineers but I've regularly seen them crash through the ice when they signed off on a layout and the EMC lab session ended with a thick forest. That's when my phone rings :-) -- Regards, Joerg http://www.analogconsultants.com/ _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
