test-drb

test-drb@ccmp.vtda.org

101090 discussions

by shoppa＠trailing-edge.com

A couple points made in the past day that I can't resist following up on with my contradictory experience: > I think, rather, that that's a good portion of the explanation of why they > were so slow. > Ballpark example, take a 12AU7: the sum of the grid-to-plate and > grid-to-cathode capacitance is around 3 pF. Suppose the network resistance > feeding the grid circuit is 250 KOhm, that's an RC time constant of 0.75uS, > a little better than just 1 MHz. (R can be reduced of course but power > consumption is then on the climb.) > > (Not to say there weren't other reasons they were slow..) In fact, if you build similar flip-flop circuits out of transistors (essentially RTL) you'll end up with very similar counting speeds. The same tricks that speed up transistor flip-flops will speed up tube flip-flops: First you add some "speedup capacitors" to help overcome grid/base capacitance storage effects. Then you start eating away at your component variation/supply voltage variation margins to get extra speed at the cost of hand-picked parts. Then you start thinking about active pull-ups instead of just resistive pullups. Then you go to totem-pole structures. The concept works the same in both tubes and transistors. But until IC's you don't see it used an awful lot because with discretes, totem poles mean more parts. Even into the 80's NMOS and PMOS were still cutting edge and then the chip industry didn't go whole-heartedly into CMOS until the mid-80's. Brent wrote: > And how feasible would it have been to replace those ring counters with 4-bit > binary decade counters to save a lot of tubes? Perhaps it wouldn't have helped > much because of the way the values from each counter were transmitted around > the machine. Binary counters were around by then of course, I'm not sure when > binary counters were first wrapped into decade counters ( by late 40's at > latest). Both BCD counters and ring counters made out of tubes were around before WWII, and of course both were used a lot in WWII radar equipment. The earliest reference I know is Williams, "High Speed Thyratron Automatic Counting", Proc Roy Soc May 1932, mentioned in Electronics, July 1932, p 232. The flip-flop tube count difference is really very very minor: 5 tubes for a Johnson ring counter, 4 tubes for a BCD counter, and the BCD counter takes some cleverness to avoid the use of diodes (in the 50's could've been either vacuum or solid state) for gating. And the ring counter is much more easily decoded into ten digits for display. >From a purity point of view, the ring counter has some huge advantages in glitch-free decoding. But just like 70's TTL implementations, most designers were blissfully unaware of the glitches that messed up many of their circuits :-). Note that a lot of tube decade counters even into the 60's didn't use strict BCD or string ring arrangements, instead they always chose an arrangement that was most easily decoded for the application. Note that even in solid state IC form both schools are thoroughly established: The CMOS 4017 is a ring counter, the TTL 7490 is a BCD counter. Usually the ring counter was used where there was no need for any BCD coding. And the TTL nerds who didn't understand ring counters always used 7490's followed by a 7442 decoder when they wanted 10 decoded outputs, when they should've been using a ring counter to begin with! Tim.

17 years, 8 months

Subject: Re: Wanted: vacuum tube logic circuits

by wbblair3＠yahoo.com

Chuck Guzis wrote: > My first exposure to very-low plate voltage applications > was with a code-practice oscillator built from a circuit in the ARRL > Radio Amateur's Handbook. ISTR it used a 6SN7 that used the > 6.3v from the heater winding as plate voltage. At any rate, it would > drive a pair of earphones. Perhaps someone with a RAH collection > from the 1950's might locate the circuit. Thank you! That's the perfect tube multivibrator lead which allowed me to find these references using "code oscillator" and "6SN7" as search terms: p29, Dec '55: "A Heterodyne Crystal Calibrator AND CODE PRACTICE OSCILLATOR" uses both halves of a 7N7, 6SN7, or 12AU7 (or pairs of many triodes) and two crystals to give marker signals at the DIFFERENCE of the two crystals p41, Jun '52: "...Frequency Standard...Oscillator" uses a 6F6 oscillator, both halves of a 6SN7 as a multivibrator p30, Mar '62: Uses a 6AU6 oscillator at 100 kc and a 12AU7 multivibrator to also give 50 kc markers p33, Jan '65: Uses a 6AQ5 oscillator at 100 kc and a 6AS6 10-kc sub-harmonic generator (no diode and NO inductors!) p34, May '65: Uses a 6AU6 oscillator at 100 kc, a 12AU7 multi- vibrator for 10 kc points, and another 12AU7 All of these and more were found here: http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.homebrew/2007… Do you recall if the p29, Dec '55 project was the 6.3V plate voltage project you mentioned? The successful use of 6.3V as the plate voltage in a multivibrator using a standard HV tube is extremely encouraging. The lowest voltage used for the audio circuits I've built was 24V which was most likely used to put the tubes in a more linear operating region which wouldn't be necessary with a multivibrator. > While dual (identical) pentodes aren't too common for > you to use the first grid as a space-charge element, > I wonder if one of the sync-separator tubes, such as the > 6BU8 might not do the trick. Single cathode and first grid, > independent 3rd grids and plates. Thanks, that will be an interesting thing to try. > In the 20's and 30's before small-geometry power > tubes became available, "microwave" experimenters would take a > hefty triode and put a high positive voltage on the grid and a > slightly negative voltage on the plate to induce Barkhausen > oscillation. But that has nothing to do with your problem, so > forget that I mentioned But thanks for mentioning it anyway since I'm interested in reading about any unusual operating modes for tubes. Bill

17 years, 8 months

HandyMan for Kaypro

by ajp166＠bellatlantic.net

> >Subject: HandyMan for Kaypro > From: "tonym" <tonym at compusource.net> > Date: Sun, 31 Aug 2008 06:02:12 +0000 (GMT) > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >I asked a while back on comp.os.cpm, and didn't get much response... > >Anyone remember how to use a HandyMan for the kaypro? >This was an add-in board, piggy-backed between the Z80 and socket, and had a TSR-like pop-up >Borland SideKick wanna-be. > >Trying to find some info, as a K10 I acquired came with a handyMan, and Advent 1MB RAMDisk, >and K4 came with an Advent Clock, RamDisk, ProGraphics board, Personality module, and 5mHz turboboard. > > >Tony I ahve the Advent 1mb ramdisk and handyman with RTC plus the personality card for the disks on my 4/84. Right now I'm up to my eyeballs to dig out the docs but I do have them. To use handyman I think it was a control key sequency that brings it up. Allison

17 years, 8 months

Sun Sparc AXi mainboard, Sparc 10 RAM, and other stuff free or cheap

by tonym＠compusource.net

Figured I'd take advantage of the long weekend to go through stuff in the garage. Got a Sun single CPU AXi motherboard, the one they made to build into clone cases. Includes: Mainboard with dongle for kb and mouse, ATX power connector, has I/O panel for ATX case. (2) 64MB Sticks (2) 256MB Sticks (2) processors: 360mHz 501-5148, and a 333mHz 501-5090 Don't think it was ever used, and if it was, it was for a matter of days! Can't guarantee it, but it's cheap enough! Pay shipping + $10 SHOULD fit into a Priority Mail box, so figure around $20 shipped. (3) Sun 501-2273 16MB modules for Sun Sparc 10, Sun barcoded. Free+$10 Priority Mail shipping Apple II Plus - powers up, but a bunch of junk on the screen, but case is pretty flawless last I checked. $50+shipping Apple IIC - pretty clean, minimal yellowing, includes PSU, and an original DOS 3.3 system master, and I can dig up a few more original disks to go with it $50+shipping. Does work, but the monitor IIc I had croaked. Got a stack of manuals, in binders, and some disks, for H/Z Z-100.I BELIEVE Bill Loguidice wanted them, so if he doesn't, available for shipping - Media Mail doable on this, as it's manuals and disks. Shouldn't be more than $10-15 MMail. I'll keep pulling over the weekend.... Tony

17 years, 8 months

Uses for OpenVMS

by thrashbarg＠kaput.homeunix.org

Hi, I've had a VAXstation 4000/60 in my cabinet for well over a year now (had to renew the license a few days ago). It is running OpenVMS 7.3. I can not think of any use for it, other than learning about OpenVMS, but that is made difficult when I don't know what to do with it... So what can be done with an OpenVMS setup these days? Also, if anyone wants an account they're welcome, just email me. Alexis.

17 years, 8 months

free: 75-node supercomputer

by bert＠brothom.nl

Hi, I'm looking for a new home for my 75-node pentium pro supercomputer. This came from the university: http://www.cs.vu.nl/das Picture: http://bert.brothom.nl/gallery2/main.php?g2_view=core.DownloadItem&g2_itemI… Each node has Linux installed. One case contains 3 CPU systems. There are 25 cases, so 75 CPUs. This takes up at least 4 19" cabinets. Contact me if you want to have it. It's free. Regards, Bert

17 years, 8 months

Video tour at the MARCH computer museum

by evan＠snarc.net

Hello cctalk'ers. Here at the MARCH computer museum, where we're hosting VCF East in two weeks >from now, we decided to make a short video tour of the first of our four exhibit rooms. The video itself, just like our museum facility, is very much "under construction" .... we'll probably need another two or three "takes" of the video to really have it come out well. Also, most of the computers in this exhibit room DO operate, although they're switched off in the video. So, please watch it, feel free to laugh at my on-camera anxiety, and please visit us in person someday (or Sept. 13-14 for the VCF East!) .... here goes: <http://www.youtube.com/watch?v=tksMbWfTssU> http://www.youtube.com/watch?v=tksMbWfTssU And yes, that really is our club-owned Straight-8 in the middle!! -Evan

17 years, 8 months

HP 64000

by hpjimbondoris123＠dorisland.net

Hello All: I have one of these HP 64000 Development Systems and I am looking for hardware and software for it. I would like to chat with other whom might own one as well. A friend and I have been working on a wikipedia page for the 64000 please check it out http://en.wikipedia.org/wiki/HP_64000 Any help would be greatly Appreciated. Jim

17 years, 8 months

HandyMan for Kaypro

by tonym＠compusource.net

I asked a while back on comp.os.cpm, and didn't get much response... Anyone remember how to use a HandyMan for the kaypro? This was an add-in board, piggy-backed between the Z80 and socket, and had a TSR-like pop-up Borland SideKick wanna-be. Trying to find some info, as a K10 I acquired came with a handyMan, and Advent 1MB RAMDisk, and K4 came with an Advent Clock, RamDisk, ProGraphics board, Personality module, and 5mHz turboboard. Tony

17 years, 8 months

Looking for DTC520 schematic, etc.

by oldcpu2＠rogerwilco.org

Jeff.kaneko said: > How about a replacement controller? > I think I have a couple of these in > cold storage. > > I think this was a SCSI to MFM bridge, > originally made by Xebec or OMTI, or, > I fergit. I think I had some from both > manufacturers. > > I can check stores if you like . . . As far as I know it was a DTC original. I don't know about them being OEMed from anyone else. And I'm pretty sure it only knows how to talk to MFM drives (and floppies). It has the normal edge finger connectors for the floppies and for two ST506/MFM type drives. There are also two unused (in this system) 50-pin headers on the the other side of the board. I'd be very surprised if this was SASI/SCSI, but I have no idea what they are. The computer box connects to this through a single 50-pin ribbon cable that connects to yet another 50-pin header in the central section of the controller. Anyway, if you truly have a real DTC520 floating around in your stash, I'd be glad to hear from you. - Jared > -- J Blaser wrote: >> My old Novell 2010 CP/M computer[1] has suffered a failure >> in the Data Technologies Corp. DTC520 controller. IIRC, >> this controller can support up to 2 MFM/ST506/ST412 drives >> and 4 floppies. In my case it's only hooked up to a single >> Seagate ST-506 (5MB! Woohoo!), and a single Shugart SA450 >> 5-1/4" floppy. Apparently this controller was not too >> uncommon in the day.

17 years, 8 months

Any DG MV2000 folks out there?

by cclist＠sydex.com

An old customer has some questions about his still-in-use DG MV2000 (running AOS). Anyone well-versed who's still using one of these care to answer a few speculative questions off-list? Thanks, Chuck

17 years, 8 months

classic Mac sighting

by spectre＠floodgap.com

On the episode of Chuck tonight, which tends to have various Macs anyway such as cheesegrater G5s turned into generic boxen by blocking out the apple, I spotted Chuck repairing a Macintosh IIci (and its power supply) in the supply cage. -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com -- TRUE HEADLINE: Police To Begin Campaign To Run Down Jaywalkers -------------

17 years, 8 months

OT: Gustav

by tonym＠compusource.net

As we all communicate on different lists and forums, the storm is popping up on most of them. Those of you in the path, good luck, and God-speed - this is a REALLY serious looking beast. 150mph winds, and it was over land in Cuba. It's about to trek a couple hundred miles in REALLY warm waters, which isn't good... Living in S. Florida, I know it all too well... Don't wait until the last minute to evacuate, or to prepare. Stay safe, and evacuate if there is even a REMOTE need to. Nothing is worth more than life. Tony

17 years, 8 months

Wanted: vacuum tube logic circuits

by wbblair3＠yahoo.com

bfranchuk at jetnet.ab.ca wrote: > > Well, in case you wanted proper space charge tubes for > > your digital logic experiments. > > > > > The problem with them is HUGE filament current. > Pencil tubes look to be fun to play with, but you never > hear about them cause of the war. > http://home.netcom.com/~wa2ise/ Actually, 24 of the 41 types of space charge tubes had filament currents ranging from only 150 - 200 mA. The 12DL8 had the highest at 550 mA.

17 years, 8 months

Free Linux and OpenOffice - even if your email address doesn't

by mcguire＠neurotica.com

On Sat, August 30, 2008 5:11 pm, Tony Duell wrote: >> > Linux $0, *BSD $0, OpenOffice.org $0. And you don't have to be a >> > student or teacher. It's the same price no matter what TLD your email >> > address is behind. >> >> I would disagree with that - nothing is free. My time is worth >> something, >> and unless you are volunteering up your free >> time to support, it ain't free. > > My sanity and stress-level is worth something too. And having had > dealings with the so-called 'support deparetments' of several companies > including M$, I have ocme to the conclusion that it's quicker and cheaper > to support things muself. Although actually, I've found the support from > the authors of free software to be a lot more helpful in solving prolems > (whether caused by a bug in their code or not) than any company I've had > dealings with. I have to agree here. Further, any software that requires THAT much "support" is probably better off being dumped in favor of something better. And a person who consistently requires "support" for software is probably better off finding a new career. Support for free stuff is FAR better and FAR faster than trying to get useful information from minimum-wage nine-to-fivers that staff nearly all support departments nowadays. Thank you, no, I'd rather talk to the guy who WROTE the code...and with free stuff, you can do that. -Dave -- Dave McGuire Port Charlotte, FL

17 years, 8 months

OT-ish? McIlroy's "Synthetic English Speech by Rule"

by jzg22＠drexel.edu

(resending, original mail was eaten during list outage) > Replying yet again, a library search lists my university as apparently > having every volume of the Bell Systems Technical Journal on > microfilm, so if it turns out to have been published there I can fetch > it. Matter of fact, I should go check those out anyway... > > John I emailed McIlroy and asked him about this, he said the article was available publicly at either of the two big Bell tech centers back in the 1990s, but both are defunct now. However, he dug up a copy of the article and scanned it (including the errata for it) and posted it on his site: http://www.cs.dartmouth.edu/~doug/ (actual file link: http://www.cs.dartmouth.edu/~doug/speak.tar ) I'm still trying in vain to find the source code to or even a binary of his unix 'speak' command, which existed between unix v3 and v6. Only the man pages seem to have survived, as far as I can tell. John A. Wasser at DEC wrote a later semi-replacement command based on the NRL algorithm, and that one I've found. Later, in 1990 or thereabouts, John Bazik hacked 'libspeak', a library of prerecorded phonemes, onto Wasser's program. Even later, (1992), 'rsynth' was created, building on Bazik's work but replacing the prerecorded phonemes with a modified version of Dennis Klatt's old klsyn backend. -- Jonathan Gevaryahu jgevaryahu(@t)hotmail(d0t)com jzg22(@t)drexel(d0t)edu

17 years, 8 months

Schematics of Atanasoff-Berry Computer logic circuits?

by jzg22＠drexel.edu

I have here an old 1955 IBM "Manual of Instruction: Electronics" Publication 'Form 22-6253-0 (12-55: 11M-W)' which has some vacuum-tube based logic circuits in it (mostly simple stuff as the book seems to be at a high-school or undergraduate level and is mostly an overview). However, it doesn't list the resistor values (except for the card punch sorter circuit), and hence has the same issues as the schematics available elsewhere, it would seem. Should I scan it? Its about 100 pages, so it will take a while. -- Jonathan Gevaryahu jgevaryahu(@t)hotmail(d0t)com jzg22(@t)drexel(d0t)edu

17 years, 8 months

IFF (was Ring vs BCD counters for decades)

by aek＠bitsavers.org

> In a few years - the early 1950s - the IFF sets were SIF encoded, > where each aircraft or ship, when interrogated by a radar, would reply > with an octal pulse code 0000 to 3777. The interrogating radar would > then read the pulses, compare them to the code of the day, and modify > the video to the scopes automatically (AN/UPX-1, AN/APX-25, AN/UPA-24, > for those paying attention) to the operator could call the shots. I > think there are remnants of this ancient system still in use. Aviation transponder squawk codes are the obvious ones, octal, 0 -> 7777

17 years, 8 months

Wanted: vacuum tube logic circuits

by ajp166＠bellatlantic.net

> >Subject: Re: Wanted: vacuum tube logic circuits > From: "bfranchuk at jetnet.ab.ca" <bfranchuk at jetnet.ab.ca> > Date: Sat, 30 Aug 2008 17:57:30 -0600 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >William Blair wrote: >> Actually, 24 of the 41 types of space charge tubes had filament currents ranging from only 150 - 200 mA. The 12DL8 had the highest at 550 mA. >> >I remember reading somewhere on the web about the high current. I did not dig any more. >As for pencil tubes ... I suspect most of them where for WWII use and the general public did not >know about them till after transistors made their impact. > > Not quite. Tthere were several forms of pencil tubes and the smaller ones were appearing in hearing aids and others small devices just after the war. The ones that were less known were the hyper rugged ones used in the VT fuses and those were mostly secret. I have a dozen or more of the pencil types some fo the 1AD4 class with 1.5V filiments and the other the harder and more rugged types with 6.3V heaters. I"ve built gear around both. Allison

17 years, 8 months

tube logic

by rdawson16＠hotmail.com

I think I replied to the bounces link I wanted to share this guy with you, that has a nixie all in tubes: http://www.jogis-roehrenbude.de/Leserbriefe/Bruegmann-Digital-Roehren-Clock… a couple of flip flops is my starting project. I will do a spice/pspice simulation too - re-enter these schematics in Cadence Concept HDL BTW, go to linear tech for a fee spice unlimited. Dont ask me for the URL, its like asking for URL to NASA Randy _________________________________________________________________ Talk to your Yahoo! Friends via Windows Live Messenger. Find out how. http://www.windowslive.com/explore/messenger?ocid=TXT_TAGLM_WL_messenger_ya…

17 years, 8 months

book offer

by rtellason＠verizon.net

>From a conversation elsewhere, where he'd expressed some interest in this machine: > > I remember us touching on that machine once before, in offlist emails. > > I'd mentioned a book I had, and after that was digging in boxes looking > > for it. > > > > Turns out the silly thing is sitting out on a bookshelf, imagine > > that! :-) > > > > It's "Programming the IBM 1130" by J. K. Hughes. If you want it or > > know of someone who does, let's talk... > > I have it! I scoured Alibris looking for anything related to the IBM 1130 > and bought everything I could find. Hughes' book is very good. FWIW, there > is a copy at Alibris (used book seller) for $20.00 Maybe you can get a few > bucks for it. > > Richard Anybody care to offer me a few bucks for this? I can use all the help I can get, beyond shipping costs... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

17 years, 8 months

Wanted: vacuum tube logic circuits

by wbblair3＠yahoo.com

William Donzelli wrote: > I have exactly one 12U7 in stock. I have a few 12K5s, as > well. I've now got a number of different dual triode tubes to try from a local electronics shop that has a large collection of tubes from former TV and radio repairmen. $1 each and they have a B&K 707 tube tester to test them on. > One thought about using space charge tubes for logic - they > might end up being slow as molasses. >From a message above, it looks like even a 6.3V plate voltage on a standard (not low voltage) dual triode tube will work and I'm after a visibly slow (a few Hz at most) multivibrator anyway with a binary counter circuit attached.

17 years, 8 months

Looking for DTC520 schematic, etc.

by jeff.kaneko＠juno.com

How about a replacement controller? I think I have a couple of these in cold storage. I think this was a SCSI to MFM bridge, originally made by Xebec or OMTI, or, I fergit. I think I had some from both manufacturers. I can check stores if you like . . . Jeff -- J Blaser <oldcpu2 at rogerwilco.org> wrote: [Repost, now that the list is back up... (Thanks, Jay!)] My old Novell 2010 CP/M computer[1] has suffered a failure in the Data Technologies Corp. DTC520 controller. IIRC, this controller can support up to 2 MFM/ST506/ST412 drives and 4 floppies. In my case it's only hooked up to a single Seagate ST-506 (5MB! Woohoo!), and a single Shugart SA450 5-1/4" floppy. Apparently this controller was not too uncommon in the day. In my case, the DTC520 is installed in the disk subsystem that's separate from the main terminal/computer, and they no longer will talk to each other. The problem seems to be related to the section that handles the IO between this controller and the CPU box. I've replaced one chip (74LS33) that was showing some serious corrosion on the pins/legs, thinking that maybe some of that had migrated into the IC die itself, but no change in behavior. It's still indicating a screwy logic level on one of the gates, but it must be coming in on the inputs. I need a schematic to help me trace the signals. I can't locate anything online. Does anyone have anything that could help me out...schematics, technical description, etc.? Many thanks. - Jared [1] Before there was Novell, Inc., the networking software company, there was Novell Data Systems (NDS), c. 1979. They had the big idea of creating a "Data Management Computer" (DMC) around a 68000, which acted as a micro-mini-mainframe for up to 24 intelligent terminals. While this project never really got off the drawing board, around 1980 NDS added (yet) another CPU to their intelligent terminal and stuck CP/M 2.2 on it. They sold a handful of these (I ended up with one) in an effort to generate a little cash flow while the 'real' project of the DMC was still in works. In the end, it was all a little too late and NDS collapsed in the latter half of 1982. It was at this point that Ray Noorda was recruited to revive the company, and in January 1983, Novell, Inc. was (re)born with the focus of networking primarily IBM PCs. The DMC, by the way, ended up becoming a file server (as opposed to Corvus', 3Com's, et al, 'disk (slice) server' technology) and the rest is history. Later, around 1988, Novell, Inc. dropped all hardware products to focus exclusively on their NetWare software. ____________________________________________________________ Save time with Cable Internet. Click here http://thirdpartyoffers.juno.com/TGL2141/fc/Ioyw6i3mDL6LyJj9bvQ6kMSZ9kulwFP…

17 years, 8 months

Wanted: vacuum tube logic circuits

by ajp166＠bellatlantic.net

> >Subject: Re: Wanted: vacuum tube logic circuits > From: William Blair <wbblair3 at yahoo.com> > Date: Sat, 30 Aug 2008 07:58:29 -0700 (PDT) > To: cctalk at classiccmp.org > >William Donzelli wrote: > >> I have exactly one 12U7 in stock. I have a few 12K5s, as >> well. > >I've now got a number of different dual triode tubes to try from a local electronics shop that has a large collection of tubes from former TV and radio repairmen. $1 each and they have a B&K 707 tube tester to test them on. > >> One thought about using space charge tubes for logic - they >> might end up being slow as molasses. > >>From a message above, it looks like even a 6.3V plate voltage on a standard (not low voltage) dual triode tube will work and I'm after a visibly slow (a few Hz at most) multivibrator anyway with a binary counter circuit attached. Most all of the space charge tubes were optimized for 12V plates. IF you can run 12V to 25V range you limit yourself less as even generic 12AX7s, 12ATs and 12AU7s perform serviceably there. Allison

17 years, 8 months

Subject: Re: Wanted: vacuum tube logic circuits

by ajp166＠bellatlantic.net

> >Subject: Subject: Re: Wanted: vacuum tube logic circuits > From: William Blair <wbblair3 at yahoo.com> > Date: Sat, 30 Aug 2008 07:42:53 -0700 (PDT) > To: cctalk at classiccmp.org > >Chuck Guzis wrote: > >> My first exposure to very-low plate voltage applications >> was with a code-practice oscillator built from a circuit in the ARRL >> Radio Amateur's Handbook. ISTR it used a 6SN7 that used the >> 6.3v from the heater winding as plate voltage. At any rate, it would >> drive a pair of earphones. Perhaps someone with a RAH collection >> from the 1950's might locate the circuit. > >Thank you! That's the perfect tube multivibrator lead which allowed me to find these references using "code oscillator" and "6SN7" as search terms: > >p29, Dec '55: "A Heterodyne Crystal Calibrator AND CODE PRACTICE >OSCILLATOR" uses both halves of a 7N7, 6SN7, or 12AU7 (or pairs of many triodes) and two crystals to give marker signals at the DIFFERENCE of the two crystals > >p41, Jun '52: "...Frequency Standard...Oscillator" uses a 6F6 >oscillator, both halves of a 6SN7 as a multivibrator > >p30, Mar '62: Uses a 6AU6 oscillator at 100 kc and a 12AU7 >multivibrator to also give 50 kc markers > >p33, Jan '65: Uses a 6AQ5 oscillator at 100 kc and a 6AS6 10-kc >sub-harmonic generator (no diode and NO inductors!) > >p34, May '65: Uses a 6AU6 oscillator at 100 kc, a 12AU7 multi- >vibrator for 10 kc points, and another 12AU7 > >All of these and more were found here: > >http://newsgroups.derkeiler.com/Archive/Rec/rec.radio.amateur.homebrew/2007… > >Do you recall if the p29, Dec '55 project was the 6.3V plate voltage project you mentioned? > >The successful use of 6.3V as the plate voltage in a multivibrator using a standard HV tube is extremely encouraging. The lowest voltage used for the audio circuits I've built was 24V which was most likely used to put the tubes in a more linear operating region which wouldn't be necessary with a multivibrator. > >> While dual (identical) pentodes aren't too common for >> you to use the first grid as a space-charge element, >> I wonder if one of the sync-separator tubes, such as the >> 6BU8 might not do the trick. Single cathode and first grid, >> independent 3rd grids and plates. > >Thanks, that will be an interesting thing to try. > >> In the 20's and 30's before small-geometry power >> tubes became available, "microwave" experimenters would take a >> hefty triode and put a high positive voltage on the grid and a >> slightly negative voltage on the plate to induce Barkhausen >> oscillation. But that has nothing to do with your problem, so >> forget that I mentioned > >But thanks for mentioning it anyway since I'm interested in reading about any unusual operating modes for tubes. > >Bill I just got finished builting a recieving converter and used 12V as Plate voltage with good success using standard 12BA6 for RF amp, mixer and osc functions as I couldn't find my supply of 12EK7s. The 12BA6 nominally is speced at 150V for plate. The assumption is that triode tube are required for logic is also false. If the goal is to stay away from scary voltages I'd suggest 22.5, 45 or 67V as they are easy to obtain and most any tube performs resonably in that range. Running below 12V is harder and narrows ones choices. Allison

17 years, 8 months

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test-drb