test-drb May 2003

test-drb@ccmp.vtda.org

284 participants
500 discussions

by pete＠dunnington.u-net.com

On May 25, 22:05, Steve Leach wrote: > If you could humor my electronic ignorance, what exactly IS a tantalum > cap and how does it differ from a normal capacitor? I was never before > aware that there could be more to a capacitor than plates (or foil) and > an electrolyte. How can a capacitor have a polarity? Almost all electrolytic caps are polarised. In principle, a tantalum capacitor is just like an aluminium electrolytic, only using a more exotic metal (tantalum pentoxide has a dielectric constant about 4-5 times higher than aluminium oxide) and a solid electrolyte. The anode is the foil (or bead, if it's sintered tantalum tantalum), the oxide layer on it is the dialectric, and the electrolyte is the cathode. Passing current from cathode to anode will build up the oxide layer, the other way will break it down. From a chemist's point of view, putting electrons into the cathode and taking them out of the anode makes some of the metallic aluminium (Al) ionise into Al+++, and if there are oxygen ions (O--) adjacent, it forms alumina (Al203) -- standard RedOx reaction, exactly the same as anodising aluminium for protection. You have to maintain the polarity to maintain the oxide layer; if you reverse it the electrons will break down the oxide layer. The aluminium ions would gain electrons, the oxygen ions would lose them, the alumina becomes aluminium and oxygen, and then you have no more highly-insulating aluminium oxide dielctric. Think of the aluminium-alumina junction as a junction diode, with a very high resistance in one direction and a very low resistance the other way. There's a brief description of construction at http://www.chipcenter.com/eexpert/akruger/akruger006.html -- Pete Peter Turnbull Network Manager University of York

21 years, 1 month

Software for NCD 17c Xterminal

by julesrichardsonuk＠yahoo.co.uk

Hi, > I got a nice NCD 17c X terminal a while back, but I don't > have the server software to download to it. Does anyone > have such software or a pointer to where to get it? If you just need the boot image, I think you're looking for a file called "Xncd17c" - I use Xncd19c for my 88k-based xterm (or did, last time I used it for anything!) These used to be freely available on ftp.ncd.com (up until 2 years ago for sure) in their own "older units" directory tree but seem to have vanished. However a quick google returned: http://www.stat.wisc.edu/p/stat/tftpboot/cs/Xncd17c ... which may be exactly what you need. Set up a tftp server somewhere with the image on and you're away :) cheers, Jules __________________________________________________ It's Samaritans' Week. Help Samaritans help others. Call 08709 000032 to give or donate online now at http://www.samaritans.org/support/donations.shtm

21 years, 1 month

Tektronix 2430A overshot (overrange) can't pass self-diagnostics

by cli＠pholink.com

Hi: The Tek 2430A input is "50 Ohm 5V RMS". I put 200V in CH1, then smell something. after that the 2430A can't pass the Extended-Diagnostics! (CH2 is OK). Does anyone know which component was burnt away? thanks Li 0000 Extended -Diagnostics 1000 Sys-Rom Pass 2000 Reg Pass 3000 Sys-Ram Pass 4000 FPP Pass 5000 WP Pass 6000 Cksum-Nvram Pass 7000 CCD Pass 8000 PA Fail 8100 Offset Fail 8110 Norm-SP Fail 8111 CH1 Fail 8112 CH2 Pass 8120 Norm-FISO Fail 8121 CH1 Fail 8122 CH2 Pass 8130 ENV-SP-slow Fail 8131 CH1 Fail 8132 CH2 Pass 8140 ENV-FISO-slow 8141 CH1 Fail 8142 CH2 Pass 8200 Pos-Agin Fail 8210 CH1 Fail 8220 CH2 Pass 8300 Balance Fail 8310 50mV Fail 8311 CH1 Fail 8312 CH2 Pass 8320 20mV Fail 8321 CH1 Fail 8322 CH2 Pass 8330 10mV Fail 8331 CH1 Fail 8332 CH2 Pass 8340 5mV Fail 8341 CH1 Fail 8342 CH2 Pass 8350 2mV Fail 8351 CH1 Fail 8352 CH2 Pass 8400 Gain Fail 8410 50mV Fail 8411 CH1 Fail 8412 CH2 Pass 8420 20mV Fail 8421 CH1 Fail 8422 CH2 Pass 8430 10mV Fail 8431 CH1 Fail 8432 CH2 Pass 8440 5mV Fail 8441 CH1 Fail 8442 CH2 Pass 8450 2mV Fail 8451 CH1 Fail 8452 CH2 Pass 8500 INV-Gain Fail 8510 50mV Fail 8511 CH1 Fail 8512 CH2 Pass 8520 20mV Fail 8521 CH1 Fail 8522 CH2 Pass 8530 10mV Fail 8531 CH1 Fail 8532 CH2 Pass 8540 5mV Fail 8541 CH1 Fail 8542 CH2 Pass 8550 2mV Fail 8551 CH1 Fail 8552 CH2 Pass 8600 Var-Max Fail 8610 CH1 Fail 7620 CH2 Pass 8700 Attenuator * Pass 9000 Trigs Fail 9100 Offset Fail 9110 A-trig Fail 9111 CH1 Fail 9112 CH2 Pass 9113 Slop Fail 9114 Ext1X1* Pass 9115 Ext1X5* Pass 9116 Ext2X1* Pass 9117 Ext2X5* Pass 9120 B-trig Fail 9121 CH1 Fail 9122 CH2 Pass 9123 Slop Fail 9124 Ext1X1* Pass 9125 Ext1X5* Pass 9126 Ext2X1* Pass 9127 Ext2X5* Pass 9200 Gain Fail 9210 A-trig Fail 9211 CH1 Fail 9212 CH2 Pass 9213 Ext1X1* Pass 9214 Ext1X5* Pass 9215 Ext2X1* Pass 9216 Ext2X5* Pass 9220 B-trig Fail 9221 CH1 Fail 9222 CH2 Pass 9223 Ext1X1* Pass 9224 Ext1X5* Pass 9225 Ext2X1* Pass 9226 Ext2X5* Pass 9300 Repet* Pass

21 years, 1 month

[Fwd: [B205] Re: Reel Tape for B9 Builders]

by bfranchuk＠jetnet.ab.ca

you guys may need 3 inch tape some day too! -------- Original Message -------- Subject: [B205] Re: Reel Tape for B9 Builders Date: Mon, 26 May 2003 04:24:01 -0000 From: "Stan Brewer" <brewers(a)ftc-i.net> Reply-To: B205(a)yahoogroups.com To: B205(a)yahoogroups.com There is one last chance to buy a 3inch reel tape for your B9. I have ten tapes, and once they are gone, thats it. See ebay Item # 3026315320 for a dutch auction. Stan --- In B205(a)yahoogroups.com, "Stan Brewer" <brewers@f...> wrote: > Are you building a full sized B9 robot and need a 3 inch > reel to reel tape for the programming bay? > > Have you filled up the tape on your current B9? > > Do you just want some part of a B9? > > If so, check out the ebay auction Item # 3024945469. > > Stan ------------------------ Yahoo! Groups Sponsor ---------------------~--> Get A Free Psychic Reading! Your Online Answer To Life's Important Questions. http://us.click.yahoo.com/Lj3uPC/Me7FAA/CNxFAA/SyTolB/TM

21 years, 1 month

!HELP!! ALTAIR BLEW SMOKE!!!

by stevenaleach＠mac.com

>What type of switches are they? Toggle? Rotary? Both C&K and Alco both >manufacture a huge variety of switches, one of which is bound to be a very >close, if not an exact replacement. Are the original switches not >repairable? These are toggle switches with two closed positions and three contacts, ie two on positions and a common ground in the middle. My problem is finding the correct dimensions, ie spacing between connectors as well as height above the board and the length and width of the "neck" to protrude through the panel..

21 years, 1 month

Collection policy

by mranalog＠attbi.com

"TeoZ" wrote: > Like I said before museums have static displays for reasons of > power requirements, lack of personnel that can run the machines, > spare parts that are expensive and hard to find, and the fact > that a screwup during operation could actually destroy one of > the few remaining examples (or only one). Most devices in a > museum are there for either art or function (or combination). And then some museums don't. There are many techniques to avoid static displays. * Rotating the equipment on a turntable with the back open. * Recreating really old equipment or high wear parts. * Equipment displays with interactive java simulation of the equipment running nearby. * Faking the output display on unpowered equipment with the 'PC behind the curtain'. * Or just using equipment that is still some what available. And don't forget the importance of the the right lighting and sound effects. :) I am currently trying to help a gentleman restore a EAI TR-48 desktop analog, from the early 60s, on display in the Retro Beep Computer Museum at Bletchley Park. He wants to run a repetitive simulation for visitors to see. I asked him if the recreated Colossus is actually operated for vistors to the museum. He replied: > The Colossus is running for the visitors to see; > however, there is not a guided viewing with everything > explained and messages decoded etc. You can see the > paper tape loop flying round the bedstead and there > is an oscilloscope for the visitors to see the read > in bit sequence. Also, the machine is behind a wall > with windows because all the frames are open +/- 100 > volts DC and thus not safe for the public to directly > approach. Also, there are various items for everyone > to read on display to explain things. > There is a guided tour of the site with explanations > of the code breaking centres; the Colossus bit is > unguided. I also asked about interactive displays. He reply: > You get to play with the enigma machine I think and > there is a bit of code breaking you can do. > Also, in the Retro beep museum, there are several old > digital personal machines to play with; including Sinclair > spectrums, BBC computers etc ? not very exciting for an > engineer but the kids love them. Also there is a rare > Apple Lisa with original disc system. As well as the > Elliott 803 there are a couple of DEC machine, one of > them being an old original (with front doors made from > kitchen worktops ? as specified by DEC?s founder). He also sent me links to some wonderful interactive web pages, including the 'Virtual Turing Bombe', the 'Virtual 3 wheel Naval Enigma', the 'Virtual 3 wheel Army/Air Force Enigma' and the 'Virtual Colossus'. ENIGMA, BOMBE, and COLOSSUS Links Codes and Ciphers in the Second World War http://www.codesandciphers.org.uk/ Great link on the Enigma code, the Turing Bombe, and on the Colossus Click on Tony Sale's reconstruction of Enigma decipherment for the film Enigma or go directly to this page http://www.codesandciphers.org.uk/enigmafilm/index.htm Making the Enigma ciphers for the film "Enigma" by Tony Sale Or if you don't want to go through the explaination of the Enigma code and how it was broken, you can go directly to these interactive web pages http://www.codesandciphers.org.uk/enigmafilm/bombe/bombe1.htm Virtual Turing Bombe by Tony Sale http://www.codesandciphers.org.uk/enigmafilm/emachines/enigman.htm Virtual 3 wheel Naval Enigma by Tony Sale http://www.codesandciphers.org.uk/enigmafilm/emachines/enigma1.htm Virtual 3 wheel Army/Air Force Enigma by Tony Sale Or try http://www.codesandciphers.org.uk/lorenz/rebuild.htm The Colossus Rebuild Project which links to http://www.codesandciphers.org.uk/virtualbp/fish/vcolossus.htm Virtual Colossus by Tony Sale And the Bombe Rebuild Project http://www.jharper.demon.co.uk/bombe1.htm --Doug ========================================= Doug Coward @ home in Poulsbo, WA Analog Computer Online Museum and History Center http://dcoward.best.vwh.net/analog =========================================

21 years, 1 month

Software for NCD 17c Xterminal

by djenner＠earthlink.net

I got a nice NCD 17c X terminal a while back, but I don't have the server software to download to it. Does anyone have such software or a pointer to where to get it? Thanks, Dave -- David C. Jenner djenner(a)earthlink.net

21 years, 1 month

PDP 11/34 rebuild

by pete＠dunnington.u-net.com

On May 25, 17:32, Greg Elkin wrote: > The 11/34a I collected recently (BA11-L chasis, H777 PSU) and had > difficulty getting to power up is in better shape now that it's had a > good clean ; backplane inspected and all the dust & debris removed > from its slots (via "fart in a can", ie compressed air :), the cards > have had their edge connectors cleaned (india rubber) to be nice and > shiny. > > Switching to DC ON, the fans whirr happily and the front panel now > has "DC ON" and "RUN" LEDs on, with 000000 on the 7seg LEDs. > > If I try to halt (keypad CNTRL + HLT/SS), the RUN LED stays on and > BUS ERR LED also comes on. FAQ. This is the result of having a 9302 terminator, whichg asserts SACK, and a missing NPR jumper somewhere. Either you have a card missing, or you've put a card that doesn't pass NPR into a slot where previously there was a card that did (or you've put a small grant card where you should have a full-size one). Ethan mentioned this in response to one of your posts recently, and Tony (on more than one occasion) explained in detail why this has the effect it does. http://www.classiccmp.org/pipermail/cctalk/2003-May/022031.html http://www.classiccmp.org/pipermail/cctalk/2003-May/022051.html Don't feel *too* bad about it, I got caught myself with that, once. -- Pete Peter Turnbull Network Manager University of York

21 years, 1 month

!HELP!! ALTAIR BLEW SMOKE!!!

by stevenaleach＠mac.com

I just retrieved an Altair 8800B from long term storage. I blew away the dust, checked for loose connections, and finally powered it up. Lights flickered to life, and then smoke poured from the front panel. I pulled it apart, and found a very crispy capacitor number C4 on the front panel card. My first problem is that this capacitor is so crispy that I have no way of determining the proper value. It is (was) connected to a voltage regulator marked "F 79MO8 AUC 7535"

21 years, 1 month

Trenton Computer Festival

by cb＠mythtech.net

>I wish I'd picked up one of the 68k Apples. I'm sure >the Hamvention will have scads of them though. Any particular model you are interested in? I have some extra 68k Macs here, maybe I have an extra of a model you are looking for -chris <http://www.mythtech.net>

21 years, 1 month

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test-drb May 2003