cctalk Digest, Vol 105, Issue 48 - test-drb@ccmp.vtda.org

21 May 2012

----- Original Message ----- 
From: <cctalk-request at classiccmp.org>
To: <cctalk at classiccmp.org>
Sent: Monday, May 21, 2012 5:08 PM
Subject: cctalk Digest, Vol 105, Issue 48

...
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 Today's Topics:

   1. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (Adrian Stoness)
   2. Re: Free (for the price of shipping) RA-81 chassis (Alan Perry)
   3. Re: VT220 focus (Liam Proven)
   4. RE: BA23 PDP11/23 Power Supply that couldn't; Trying to
      locate a replacement cap  (Shoppa, Tim)
   5. RE: BA23 PDP11/23 Power Supply that couldn't; Trying to
      locate a replacement cap (Chuck Guzis)
   6. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (John Foust)
   7. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (David Griffith)
   8. Re: Software for OCR'ing paper tape? (Dave McGuire)
   9. Re: VT220 focus (Dave McGuire)
  10. Re: Software for OCR'ing paper tape? (Adrian Stoness)
  11. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (Ethan Dicks)
  12. Re: VT220 focus (David Riley)
  13. Re: Software for OCR'ing paper tape? (Dave Wade)
  14. Re: VT220 focus (Cameron Kaiser)
  15. Re: VT220 focus (Dave McGuire)
  16. kryoflux or discferret enclosures (David Griffith)
  17. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (Chuck Guzis)
  18. Re: BA23 PDP11/23 Power Supply that couldn't; Trying to
      locate a (Tony Duell)
  19. Re: BA23 PDP11/23 Power Supply that couldn't; (Tony Duell)
  20. Re: BA23 PDP11/23 Power Supply that couldn't; Trying to
      locate a (Tony Duell)
  21. Re: Baudot? (Was: Question about Military terminal (Tony Duell)
  22. Re: Baudot? (Was: Question about Military terminal (Tony Duell)
  23. Re: VT220 focus (Tony Duell)
  24. Re: How to contribute to bitsavers? (Richard)
  25. Re: Software for OCR'ing paper tape? (was: Question about
      Military terminal) (Richard)
  26. Re: AVL ROAD RUNNER...My father built it (Richard)
  27. Re: CRT degaussing coil (was Re: PDP-11/35 power supply woes)
      (John Honniball)
  28. Re: VT220 focus (ben)
  29. RE: Software for OCR'ing paper tape? (dwight elvey)

 ----------------------------------------------------------------------

 Message: 1
 Date: Mon, 21 May 2012 12:06:01 -0500
 From: Adrian Stoness <tdk.knight at gmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID:
 <CAA3rs23pg2_n5=nxiRohgTWe-zKgWY-zsmR2gcUT3_ZhUY5wVA at mail.gmail.com>
 Content-Type: text/plain; charset=ISO-8859-1

 what if one was to use a digital camera and just photograph them and then
 have a batch processor of some sort?

 On Mon, May 21, 2012 at 11:28 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:

  On Mon, May 21, 2012 at 11:54 AM, Richard
<legalize at xmission.com> wrote:
  Is there something similar for punched cards as
well? 
 I started to write one years ago (beginning with scanning the punch
 cards with a colored background to make the holes stand out) and did
 get edge and orientation detection working, but the per-card handling
 time on the scanner lead me to drop work on the project.  If you were
 scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
 You'd spend a lot of time just getting the cards in and out of the
 scanner.

 My code wasn't anything magical - it used Tom Boutell's GD library to
 imported a monochrome GIF of a scan of the *back* of the card (to
 eliminate "noise" from the printing on most cards) then did a fairly
 uninspired search for the outer boundaries, then did an estimation of
 where the holes ought to be (based on the discovered dimensions of the
 edges) and did a simple (3x3) kernel sum of the targeted coordinate
 and if it was mostly "white", it was a zero, mostly black, a one.  You
 couldn't skew the cards 45 degrees and expect it to work, but it was
 resilient enough to work with a little skew.

 -ethan

 ------------------------------

 Message: 2
 Date: Mon, 21 May 2012 10:15:09 -0700
 From: Alan Perry <alanp at snowmoose.com>
 To: cctech at classiccmp.org
 Subject: Re: Free (for the price of shipping) RA-81 chassis
 Message-ID: <4FBA781D.4000800 at snowmoose.com>
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 Oops.  Sorry.  It is at 98110. Bainbridge Island, WA, across the water from
 downtown Seattle.  I am willing to deliver it on the other side of the
 water.

 alan

 On 5/21/12 10:00 AM, cctech-request at classiccmp.org wrote:
  Not that I am likely to be able to house this,
but it might help others to
 know the location of the item.

 Regards

 Rob

> >  -----Original Message-----
> >  From:cctalk-bounces at classiccmp.org  [mailto:cctalk-
> >  bounces at classiccmp.org] On Behalf Of Alan Perry
> >  Sent: 20 May 2012 18:22
> >  To:cctech at classiccmp.org
> >  Subject: Free (for the price of shipping) RA-81 chassis
> >
> >
> >  I have a RA-81 that I am getting rid of.  It is complete except for the 
> > disks
> >  and the housing that they spin in.  It has the motor, so it is still 
> > heavy.
> >  Probably a local pickup, but I will consider shipping.
> >
> >  If there are no takers, maybe it will just appear on the Living Computer
> >  Museum's doorsteps.  Wait, Ian and Rich subscribe to this list ...
> >
> >  alan 

 ------------------------------

 Message: 3
 Date: Mon, 21 May 2012 18:14:36 +0100
 From: Liam Proven <lproven at gmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: VT220 focus
 Message-ID:
 <CAMTenCHLe5MQq9sTNUCi0M+v89hnu39WxCZiFFEVRbCZqy9TGg at mail.gmail.com>
 Content-Type: text/plain; charset=windows-1252

 On 21 May 2012 16:58, Richard <legalize at xmission.com> wrote:

 [nit: please consider hitting RETURN every 75 chars or so] 
 Please don't. Hard line-wrap has been a PITA since the 1960s and still is.

 -- 
 Liam Proven ? Profile: http://lproven.livejournal.com/profile
 Email: lproven at cix.co.uk ? GMail/G+/Twitter/Flickr/Facebook: lproven
 MSN: lproven at hotmail.com ? Skype/AIM/Yahoo/LinkedIn: liamproven
 Tel: +44 20-8685-0498 ? Cell: +44 7939-087884

 ------------------------------

 Message: 4
 Date: Mon, 21 May 2012 17:18:40 +0000
 From: "Shoppa, Tim" <tshoppa at wmata.com>
 To: "cctalk at classiccmp.org" <cctalk at classiccmp.org>
 Subject: RE: BA23 PDP11/23 Power Supply that couldn't; Trying to
 locate a replacement cap
 Message-ID:
 <303A17BD5F8FA34DA45EEC245271AC0B016ED6 at JGEX2K10MBX2.wmata.local>
 Content-Type: text/plain; charset="us-ascii"

  I am curious, now, as to why they used this
glass-encased "metallised
 paper" capacitor instead of, say, an electrolytic. There are many
 electrolytics inside the PSU, so it clearly wasn't a lack of availability.
 Presumably there was a specific reason they chose this type of cap over
 another. I'd hate to be wrong and do worse damage. 
 It's an X (across-the-line) capacitor, almost certainly being used as a 
 snubber.

 For across-the-line and snubber networks metalized film/paper or foil+paper 
 are still the cat's meow. They have well understood failure modes. Ceramics 
 are also rated as X safety capacitors in some circumstances.

 From the X, it's probably rated at least at
250VAC and is non-polarized. 
 This is not the job for an electrolytic or an unpolarized electrolytic.

 It is the job for a safety rated capacitor.

 Tim.

 ------------------------------

 Message: 5
 Date: Mon, 21 May 2012 10:19:15 -0700
 From: "Chuck Guzis" <cclist at sydex.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: RE: BA23 PDP11/23 Power Supply that couldn't; Trying to
 locate a replacement cap
 Message-ID: <4FBA16A3.20801.8FDE42 at cclist.sydex.com>
 Content-Type: text/plain; charset=US-ASCII

 On 21 May 2012 at 11:55, JP Hindin wrote:

  I am curious, now, as to why they used this
glass-encased "metallised
 paper" capacitor instead of, say, an electrolytic. There are many
 electrolytics inside the PSU, so it clearly wasn't a lack of
 availability. Presumably there was a specific reason they chose this
 type of cap over another. I'd hate to be wrong and do worse damage. 
 Are you talking about the infamous Rifa caps?

 That's not glass--I think it might be polystyrene.  At any rate,
 they're "safety" capacitors in that their failure mode is limited to
 a set of known conditions, none of which can lead to electrical shock
 hazard.  Generally, these are X- and Y- rated capacitors, with
 several numbered subcategories.

 X-capacitors are designed for "across the line" applications, i.e.,
 from one side of the line supply to the other.  Y-capacitors are
 designed for "line to ground" applications.

 Here's a brief FAQ on that subject:

 http://www.okaya.com/FAQ1.html

 Rifa caps are still with us, though there are X- and Y- rated
 polypropylene and polyester caps as well.

 Do not use an electrolytic, non-polar or otherwise.  They're not
 designed for the application.

 --Chuck

 ------------------------------

 Message: 6
 Date: Mon, 21 May 2012 13:04:55 -0500
 From: John Foust <jfoust at threedee.com>
 To: <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID: <201205211805.q4LI594D004524 at billy.ezwind.net>
 Content-Type: text/plain; charset="us-ascii"

 At 11:28 AM 5/21/2012, Ethan Dicks wrote:
 If you were
scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
You'd spend a lot of time just getting the cards in and out of the
scanner. 
 Well, there are many scanners that can auto-feed a half-inch-tall pile.

 As for paper tape, what about the super-duper overkill of recognizing
 a video stream from a web cam?  All you'd need is a jig to slowly
 pull the tape past the fixed camera.

 - John

 ------------------------------

 Message: 7
 Date: Mon, 21 May 2012 11:14:06 -0700 (PDT)
 From: David Griffith <dgriffi at cs.csubak.edu>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID:
 <alpine.DEB.2.00.1205211113350.31082 at sleipnir.cs.csubak.edu>
 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed

 On Mon, 21 May 2012, John Foust wrote:

  At 11:28 AM 5/21/2012, Ethan Dicks wrote:
  If you were
 scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
 You'd spend a lot of time just getting the cards in and out of the
 scanner. 
 Well, there are many scanners that can auto-feed a half-inch-tall pile.

 As for paper tape, what about the super-duper overkill of recognizing
 a video stream from a web cam?  All you'd need is a jig to slowly
 pull the tape past the fixed camera. 
 Why not simply build a paper tape reader?  It's not that hard to do.

 -- 
 David Griffith
 dgriffi at cs.csubak.edu

 A: Because it fouls the order in which people normally read text.
 Q: Why is top-posting such a bad thing?
 A: Top-posting.
 Q: What is the most annoying thing in e-mail?

 ------------------------------

 Message: 8
 Date: Mon, 21 May 2012 14:21:06 -0400
 From: Dave McGuire <mcguire at neurotica.com>
 To: General Discussion: On-Topic and Off-Topic Posts
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape?
 Message-ID: <4FBA8792.4070205 at neurotica.com>
 Content-Type: text/plain; charset=ISO-8859-1

 On 05/21/2012 02:04 PM, John Foust wrote:
   If you
were
 scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
 You'd spend a lot of time just getting the cards in and out of the
 scanner. 
 Well, there are many scanners that can auto-feed a half-inch-tall pile.

 As for paper tape, what about the super-duper overkill of recognizing
 a video stream from a web cam?  All you'd need is a jig to slowly
 pull the tape past the fixed camera. 
  This is all interesting, but seems like a solution in search of a
 problem.  Is it really the case that nobody can find a good optical
 (i.e., low tape wear) tape reader?  Or card reader?

             -Dave

 -- 
 Dave McGuire, AK4HZ
 New Kensington, PA

 ------------------------------

 Message: 9
 Date: Mon, 21 May 2012 14:26:35 -0400
 From: Dave McGuire <mcguire at neurotica.com>
 To: General Discussion: On-Topic and Off-Topic Posts
 <cctalk at classiccmp.org>
 Subject: Re: VT220 focus
 Message-ID: <4FBA88DB.6010307 at neurotica.com>
 Content-Type: text/plain; charset=windows-1252

 On 05/21/2012 01:14 PM, Liam Proven wrote:
   [nit:
please consider hitting RETURN every 75 chars or so] 
 Please don't. Hard line-wrap has been a PITA since the 1960s and still is. 
  How, exactly, is it a PITA?

           -Dave

 -- 
 Dave McGuire, AK4HZ
 New Kensington, PA

 ------------------------------

 Message: 10
 Date: Mon, 21 May 2012 13:27:58 -0500
 From: Adrian Stoness <tdk.knight at gmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape?
 Message-ID:
 <CAA3rs22=oN421qKmE=KKrbhS2PkRnVS1X=TMGoWwHnGUVqsQFQ at mail.gmail.com>
 Content-Type: text/plain; charset=ISO-8859-1

 get a tripod and a camera and take photos then right some program that
 process's through them all and blam u got a way to archive ur tapes

 On Mon, May 21, 2012 at 1:21 PM, Dave McGuire <mcguire at neurotica.com> wrote:

  On 05/21/2012 02:04 PM, John Foust wrote:
   If you
were
 scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
 You'd spend a lot of time just getting the cards in and out of the
 scanner. 
 Well, there are many scanners that can auto-feed a half-inch-tall pile.

 As for paper tape, what about the super-duper overkill of recognizing
 a video stream from a web cam?  All you'd need is a jig to slowly
 pull the tape past the fixed camera. 
  This is all interesting, but seems like a solution in search of a
 problem.  Is it really the case that nobody can find a good optical
 (i.e., low tape wear) tape reader?  Or card reader?

             -Dave

 --
 Dave McGuire, AK4HZ
 New Kensington, PA

 ------------------------------

 Message: 11
 Date: Mon, 21 May 2012 14:44:00 -0400
 From: Ethan Dicks <ethan.dicks at gmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID:
 <CAALmimnFt=k6F=GWr6qkXw7d0gx+Xufo2LuuZCHKCNRQ01HWhA at mail.gmail.com>
 Content-Type: text/plain; charset=ISO-8859-1

 On Mon, May 21, 2012 at 2:04 PM, John Foust <jfoust at threedee.com> wrote:
  At 11:28 AM 5/21/2012, Ethan Dicks wrote:
 If you were
scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
You'd spend a lot of time just getting the cards in and out of the
scanner. 
 Well, there are many scanners that can auto-feed a half-inch-tall pile. 
 I was using an auto-feed scanner... Brother brand.  To get the
 contrasty background (to get the holes to show up), I loaded the punch
 card into the provided envelope for scanning receipts and small items.
 Without modifying my scanner, I could not get the background to be
 anything but white for a naked punch card.  I did not wish to hack on
 the hardware, and with all the fiddling around, it took too long per
 card to get scans.

 Yes, it's possible to hack up some hardware that gets used just for
 scanning cards.  No, I didn't care to do that.

  As for paper tape, what about the super-duper
overkill of recognizing
 a video stream from a web cam? ?All you'd need is a jig to slowly
 pull the tape past the fixed camera. 
 If I wanted to read a bunch of paper tape, I'd probably build my own
 scanner from 9 photodiodes from the article in Byte magazine.

  http://www.classiccmp.org/cini/pdf/byte/manual_ptp.pdf

 -ethan

 ------------------------------

 Message: 12
 Date: Mon, 21 May 2012 14:55:20 -0400
 From: David Riley <fraveydank at gmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: VT220 focus
 Message-ID: <EB90FE6E-B369-49AD-AE96-5D6594FEBD0F at gmail.com>
 Content-Type: text/plain; charset=windows-1252

 On May 21, 2012, at 2:26 PM, Dave McGuire wrote:

  On 05/21/2012 01:14 PM, Liam Proven wrote:
   [nit:
please consider hitting RETURN every 75 chars or so] 
 Please don't. Hard line-wrap has been a PITA since the 1960s and still is. 
  How, exactly, is it a PITA? 
 Presumably, it's a pocket-like flatbread made with whole wheat flour.
 Capitalized.

 - Dave

 ------------------------------

 Message: 13
 Date: Mon, 21 May 2012 19:55:35 +0100
 From: Dave Wade <dave.g4ugm at gmail.com>
 To: General Discussion: On-Topic and Off-Topic Posts
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape?
 Message-ID: <4FBA8FA7.6070906 at gmail.com>
 Content-Type: text/plain; charset=ISO-8859-1; format=flowed

 On 21/05/2012 19:21, Dave McGuire wrote:
  On 05/21/2012 02:04 PM, John Foust wrote:
   If you
were
 scanning a short stack of cards, it wasn't so bad, but a 3 foot deck?
 You'd spend a lot of time just getting the cards in and out of the
 scanner.  Well, there are many scanners that can auto-feed a half-inch-tall pile.

 As for paper tape, what about the super-duper overkill of recognizing
 a video stream from a web cam?  All you'd need is a jig to slowly
 pull the tape past the fixed camera.     This is all interesting, but seems like a
solution in search of a
 problem.  Is it really the case that nobody can find a good optical
 (i.e., low tape wear) tape reader?  Or card reader?

               -Dave
  I am in the UK but I have two optical tape readers, and will happily
 read tape in reasonable quantities from any one in the UK. I can also
 copy if required.
 But the question was scanned images which might be available after the
 tape has degraded and can't be read.

 Dave

 ------------------------------

 Message: 14
 Date: Mon, 21 May 2012 11:59:54 -0700 (PDT)
 From: Cameron Kaiser <spectre at floodgap.com>
 To: cctalk at classiccmp.org
 Subject: Re: VT220 focus
 Message-ID: <201205211859.q4LIxsbh12189732 at floodgap.com>
 Content-Type: text/plain; charset=US-ASCII

    > [nit: please consider hitting RETURN every 75
chars or so]

 Please don't. Hard line-wrap has been a PITA since the 1960s and still
 is. 
  How, exactly, is it a PITA? 
 Presumably, it's a pocket-like flatbread made with whole wheat flour.
 Capitalized. 
 I love those. I put them in rows of 75 columns each so that I have plenty
 and they are easy to rearrange. Then I have them with hummus.

 -- 
 ------------------------------------ personal: 
 http://www.cameronkaiser.com/ --
  Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com
 -- Laughter is the closest distance between two people. -- Victor 
 Borge -------

 ------------------------------

 Message: 15
 Date: Mon, 21 May 2012 15:10:25 -0400
 From: Dave McGuire <mcguire at neurotica.com>
 To: General Discussion: On-Topic and Off-Topic Posts
 <cctalk at classiccmp.org>
 Subject: Re: VT220 focus
 Message-ID: <4FBA9321.8050708 at neurotica.com>
 Content-Type: text/plain; charset=windows-1252

 On 05/21/2012 02:55 PM, David Riley wrote:
   > [nit: please consider hitting RETURN every 75
chars or so]

 Please don't. Hard line-wrap has been a PITA since the 1960s and still is. 
  How, exactly, is it a PITA? 
 Presumably, it's a pocket-like flatbread made with whole wheat flour.
 Capitalized. 
  Always capitalize on the pita.

              -Dave

 -- 
 Dave McGuire, AK4HZ
 New Kensington, PA

 ------------------------------

 Message: 16
 Date: Mon, 21 May 2012 12:38:22 -0700 (PDT)
 From: David Griffith <dgriffi at cs.csubak.edu>
 To: cctalk at classiccmp.org
 Subject: kryoflux or discferret enclosures
 Message-ID:
 <alpine.DEB.2.00.1205211235100.13002 at sleipnir.cs.csubak.edu>
 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII

 Does anyone here have anything to show off or point to regarding
 enclosures for the two prominent viable disk imaging boards (kryoflux and
 discferret).

 -- 
 David Griffith
 dgriffi at cs.csubak.edu

 A: Because it fouls the order in which people normally read text.
 Q: Why is top-posting such a bad thing?
 A: Top-posting.
 Q: What is the most annoying thing in e-mail?

 ------------------------------

 Message: 17
 Date: Mon, 21 May 2012 12:41:12 -0700
 From: "Chuck Guzis" <cclist at sydex.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID: <4FBA37E8.19297.111D0BD at cclist.sydex.com>
 Content-Type: text/plain; charset=US-ASCII

 On 21 May 2012 at 11:14, David Griffith wrote:

  Why not simply build a paper tape reader? 
It's not that hard to do. 
 My gosh yes.  If people can build piano-roll readers, a paper tape
 reader would be child's play.

 --Chuck

 ------------------------------

 Message: 18
 Date: Mon, 21 May 2012 20:51:16 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: BA23 PDP11/23 Power Supply that couldn't; Trying to
 locate a
 Message-ID: <m1SWYdW-000J4dC at p850ug1>
 Content-Type: text/plain

 Greetings;

 I received a new (to me) MicroPDP11/23 that I was fiddling about with over
 the weekend. After testing out the supply voltages, and then putting the
 system together enough to get serial out of it, there was a pop, a whoosh
 and a rather exciting ejected plume of smoke from one of the upper fans.

 http://www.kiwigeek.com/misc/PDP1123_Cap1.jpg
 http://www.kiwigeek.com/misc/PDP1123_Cap2.jpg 
 Yes, they do this from time to time. It's aprt of the mains filter
 sircuit, and they often fail for no really good reason.

 The capacitor is mounted on the sub-board in the PSU that the IEC
 receptacle is on.

 The markings on the back show this is a PME271M622, but I'm having trouble
 sourcing a replacement. Most of the places I usually look about are
 showing no stock or ridiculous minimum orders. On eBay (shudder) there's a
 similar model, but it's marked as an "X2", and I'm not sure if
that's an
 acceptable replacement. 
 Should be fine. From the fact that it;s 0.22uF (220nF), it's going to be
 across the mains, not from either side of the maisn to protective ground.
 In which case there are no special safety requirements 9Like it must not
 be ablto fial short-circuit). OF ocurse the capacitor ahs to be able to
 stant 250V AC continously.

 An XT one would be fine.

 -tony

 ------------------------------

 Message: 19
 Date: Mon, 21 May 2012 20:54:54 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: BA23 PDP11/23 Power Supply that couldn't;
 Message-ID: <m1SWYh2-000J4eC at p850ug1>
 Content-Type: text/plain

  These seem to blow/burst often. I believe the cap
is there only to limit RFI
 emissions, so you can leave it out safely. The power supply should run fine 
 Correct, althought it's good practice to replace it.

  without it. If you do need to replace it, I
wouldn't replace it with the
 exact same type, but with a later cap less prone to blow. Any 250V 220nF cap 
 Hmmm. I am not convinced that modern capacitors are always more reliable
 than older ones ;-)

  should do just fine. 
 Be very careful here. It has to withstand full mains voltage, which could
 be up to 250V _RMS_. In other words about 350V peak. I would not use a
 cpaacitor rated at less than 630V DC, actually.

 But it's easy to find capacitors rated for use in mains filters, and
 that's what I would fit.

 -tony

 ------------------------------

 Message: 20
 Date: Mon, 21 May 2012 20:59:10 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: BA23 PDP11/23 Power Supply that couldn't; Trying to
 locate a
 Message-ID: <m1SWYlA-000J4fC at p850ug1>
 Content-Type: text/plain

  I am curious, now, as to why they used this
glass-encased "metallised
 paper" capacitor instead of, say, an electrolytic. There are many 
 It has the AC mains across it (it's almost certianly conencted between
 live and neutral of the mains input, possibly after filter inductors). So
 it cou;dn't be an electrolytic, which are polarised and designed to have
 DC across them.

 As to why use a mrallised paper capacitro, I suspect it was the cheapest
 type that could stnad the voltage and be reliable (OK, it's failed now,
 buit it;'s been around fro proably 30 years or so). There would be no
 particualr tolerance requiremnts here.

 Wht you need to get is a capacitor of the same value that is rated to
 withstand the full mains AC votlage. Most good components suppliers list
 capcitors for mains filter applications. Since they're designed for what
 you want to use them for, theres no good reason not to use one.

 -tony

 ------------------------------

 Message: 21
 Date: Mon, 21 May 2012 20:33:19 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: Baudot? (Was: Question about Military terminal
 Message-ID: <m1SWYM9-000J4WC at p850ug1>
 Content-Type: text/plain

  >
It's about as hopeless as telling someone that a 2400 bps 201B
> modem does not run at 2400 "baud".
 Actually, it _does_ - on the host serial port.  (Unless I'm _still_
 confused about exactly what a baud is....)  Does one count start and stop bits?  In
that case, 2400 bps would be
 3000 Baud on the host serial port. 
 Hm?  I always thought serial-port "baud" rates measured raw bits per
 second.  Since I pretty much invariably use one start, 8 data, and one 
 They measure possible signal line changes per second, as you'd expect.
 And yes, start and stop bits are counted.

 In other words, a serial port baud rate of 2400 means that each bit time
 is 1/2400 s. A start bit takes that long, so does each data bit, so does
 the stop bit(s).

  stop bits, that means, eg, 2400 baud <->
240 characters per second.  (I 
 Yes.

  also thought baud rates measured the raw symbol
rate, drawing no
 distinction between data and framing symbols....) 
 AFAI Kthat is also correct. Hence the use of 'baud rate' is correct of a
 normal serial port, it measures the time taken for each bit (be it a fata
 bit or a framing control bit) to be sent.

 -tony

 ------------------------------

 Message: 22
 Date: Mon, 21 May 2012 20:36:14 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: Baudot? (Was: Question about Military terminal
 Message-ID: <m1SWYOx-000J4YC at p850ug1>
 Content-Type: text/plain

   Actually,
it _does_ - on the host serial port.  (Unless I'm _still_
 confused about exactly what a baud is....) 
 Well, then you get into the mess of what interface the modem has with
 the host.    If it's an 8-bit parallel interface, the argument could
 be made that the baud rate was 300. 
 Hmm.. Give ntaht there are now 8 signallying lines, with a possible 300
 transitions per second on each, the total number of signal line
 transitions per second remains at 2400. I think that could be classed as
 2400 baud still.

 -tony

 ------------------------------

 Message: 23
 Date: Mon, 21 May 2012 20:44:19 +0100 (BST)
 From: ard at p850ug1.demon.co.uk (Tony Duell)
 To: cctalk at classiccmp.org
 Subject: Re: VT220 focus
 Message-ID: <m1SWYWm-000J4cC at p850ug1>
 Content-Type: text/plain

 So I finally got my VT220 put back together!  I have one I saved from the 
 dumpster from a plant floor,
 but it was incredibly filthy.  I disassembled it, cleaned it thoroughly, and 
 put it back together (over a
 duration of 6+ months), and amazingly it still works!  So, I had to hook it 
 up to my MacBook Air, just
 for fun.  Works like a charm, but characters on the left seem slightly 
 fuzzier then others.  Maybe that's
 just because I've been staring at the razor-sharp screens on my MacBook and 
 iPhone too long, and
 the fact that this thing's 26 years old, but is there a way to sharpen them 
 up a bit?
 Even if not, it's still darn funny to have a physical terminal on my MacBook! 
 I thought htere wsa focus preset on the video.monitor PCB, the presets
 are all labelled on the paper overleay.

 However, AFAIK this affexcts the focus over the enitre screen. There is
 no way to focus one wide rather than the other. Now, the focus anode
 voltage is derriced from the flyback transforer, as are most of hte other
 CRT votlages (some of which could also affect the focus). So if the focus
 is much better at one side htan the otehr, it suggests one of those
 votlages has horizontal-freqeuncy ripple on it. Which to me suggests a
 defecive capacitor in one of the rectifier cirucits hung off the flyback.

 -tony

 ------------------------------

 Message: 24
 Date: Mon, 21 May 2012 14:34:58 -0600
 From: Richard <legalize at xmission.com>
 To: cctalk <cctalk at classiccmp.org>
 Subject: Re: How to contribute to bitsavers?
 Message-ID: <E1SWZJi-0001WU-OJ at shell.xmission.com>

 In article <alpine.DEB.2.02.1205211035530.19688 at linuxserv.home>,
    Christian Corti <cc at informatik.uni-stuttgart.de> writes:

  But right now I just put everything on our local
FTP
 server. 
 ....and then you can email the FTP url to Al and he can transfer to
 bitsavers if he wishes.

 That's how I do it and it works just fine.
 -- 
 "The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
     The Computer Graphics Museum <http://computergraphicsmuseum.org>
         The Terminals Wiki <http://terminals.classiccmp.org>
  Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

 ------------------------------

 Message: 25
 Date: Mon, 21 May 2012 14:36:09 -0600
 From: Richard <legalize at xmission.com>
 To: cctalk <cctalk at classiccmp.org>
 Subject: Re: Software for OCR'ing paper tape? (was: Question about
 Military terminal)
 Message-ID: <E1SWZKr-0001dp-6i at shell.xmission.com>

 In article <4FBA37E8.19297.111D0BD at cclist.sydex.com>,
    "Chuck Guzis" <cclist at sydex.com> writes:

> On 21 May 2012 at 11:14, David Griffith wrote:
>
>   Why not simply build a paper tape reader? 
It's not that hard to do. >
> My gosh yes.  If people can build piano-roll readers, a paper tape
> reader would be child's play.

 The number of people with software/mashup skills is much, much larger
 than the number of people with hardware skills.

 You may decry such a situation, but nonetheless it is the situation.
 -- 
 "The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
     The Computer Graphics Museum <http://computergraphicsmuseum.org>
         The Terminals Wiki <http://terminals.classiccmp.org>
  Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

 ------------------------------

 Message: 26
 Date: Mon, 21 May 2012 14:36:34 -0600
 From: Richard <legalize at xmission.com>
 To: cctalk <cctalk at classiccmp.org>
 Subject: Re: AVL ROAD RUNNER...My father built it
 Message-ID: <E1SWZLG-0001eP-Cu at shell.xmission.com>

 In article 
 <CAA3rs20ypc3mWNGn_JmjCpEtXVjPFQQdb9mkXrkRwmMgHs6zYQ at mail.gmail.com>,
    Adrian Stoness <tdk.knight at gmail.com> writes:

  ? 
 !
 -- 
 "The Direct3D Graphics Pipeline" free book
<http://tinyurl.com/d3d-pipeline>
     The Computer Graphics Museum <http://computergraphicsmuseum.org>
         The Terminals Wiki <http://terminals.classiccmp.org>
  Legalize Adulthood! (my blog) <http://legalizeadulthood.wordpress.com>

 ------------------------------

 Message: 27
 Date: Mon, 21 May 2012 21:49:57 +0100
 From: John Honniball <coredump at gifford.co.uk>
 To: General Discussion: On-Topic Posts Only <cctech at classiccmp.org>
 Subject: Re: CRT degaussing coil (was Re: PDP-11/35 power supply woes)
 Message-ID: <4FBAAA75.4010809 at gifford.co.uk>
 Content-Type: text/plain; charset=us-ascii; format=flowed

 Tony Duell wrote:
  Yes, some monitors degauss with quite a lound
'clang' (I assume it's the
 shaddowmask. flexing. I've never heard a TV that does that. 
 I think it's the thin steel internal screening can of a computer
 monitor that makes the "clang". And the screening is something
 that I don't think I've ever seen in a TV. Although, my Sony
 widescreen CRT TV (FreeCycle) makes a slight twang sometimes
 on power-up.

 Tony, do you remember that Tomorrow's World programme when
 Raymond Baxter showed us how to distort a TV picture with
 a magnet? And the warnings on the next week's episode
 where they said "don't try this on a colour TV!". I think
 they said that the producer had tried it on a colour set,
 and it was OK, so they broadcast it -- without realising
 that he'd been lucky, and a stronger magnet would do
 bad things.

 -- 
 John Honniball
 coredump at gifford.co.uk

 ------------------------------

 Message: 28
 Date: Mon, 21 May 2012 15:04:33 -0600
 From: ben <bfranchuk at jetnet.ab.ca>
 To: cctalk at classiccmp.org
 Subject: Re: VT220 focus
 Message-ID: <4FBAADE1.3010504 at jetnet.ab.ca>
 Content-Type: text/plain; charset=windows-1252; format=flowed

 On 5/21/2012 12:26 PM, Dave McGuire wrote:
  On 05/21/2012 01:14 PM, Liam Proven wrote:
   [nit:
please consider hitting RETURN every 75 chars or so] 
 Please don't. Hard line-wrap has been a PITA since the 1960s and still is. 
    How, exactly, is it a PITA? 
 TTY's are 72 chars wide. -:)

              -Dave

 ------------------------------

 Message: 29
 Date: Mon, 21 May 2012 14:08:18 -0700
 From: dwight elvey <dkelvey at hotmail.com>
 To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>
 Subject: RE: Software for OCR'ing paper tape?
 Message-ID: <SNT129-W2541E8D64060126342A5ACA31D0 at phx.gbl>
 Content-Type: text/plain; charset="iso-8859-1"

  From: dave.g4ugm at gmail.com

 On 21/05/2012 19:21, Dave McGuire wrote:
   I am in the UK but I have two optical tape
readers, and will happily
 read tape in reasonable quantities from any one in the UK. I can also
 copy if required.
 But the question was scanned images which might be available after the
 tape has degraded and can't be read.

 Dave  Hi I have a high speed reader to but I've had troubleswith rubber bands.
They 
 leave gunk on the tapes andlayers stick together. On a high speed reader, 
 itrips the tape before one has a chance to stop it. Mine is a parallel one and 
 I just connected it to theprinter port ( guess that dates my laptop ). A 
 simpleprogram reads the data and puts it into files. On making a reader, the 
 ideas of using a pile ofphotodiodes to read a punch card doesn't makemuch 
 sense. It might be better to have a LED lightat each hole position of a column 
 and a single photodiode.One could then just sequntially drive the lightsand 
 detect it with just one photodiode.One might need to aim each light at the 
 diode.As with Dave, if someone has fan fold paper tape toarchive, I could do 
 an reasonable amount. I'min San Jose, Ca, USA.I'm not setup to handle spooled 
 tape safely.Dwight

 End of cctalk Digest, Vol 105, Issue 48
 ***************************************