12 Aug
2008
12 Aug
'08
12:06 p.m.
Does anyone have a DEC PC04 paper tape reader/punch that they would be
interested in letting go? I'm also looking for the matching PC8-E
(M840) UNIBUS controller card.
Thanks,
-Mardy
14 Aug
14 Aug
11:49 p.m.
I think the M840 is the PDP8 controller. I don't remember the Unibus part
number, but I should have one.
Paul
On 8/12/08, Marden P. Marshall <mardy at voysys.com> wrote:
Does anyone have a DEC PC04 paper tape reader/punch that they would be
interested in letting go? I'm also looking for the matching PC8-E (M840)
UNIBUS controller card.
Thanks,
-Mardy
15 Aug
15 Aug
4:27 p.m.
I think the M840 is the PDP8 controller. I don't remember the Unibus part
number, but I should have one.
It is, that's why it's the PC8E (fits the Omnibus of the PDP8/e, amongst
others).
The unibus controller is an PC11 (I forget the M-number). But the
pumch/reader for that is a PC05, and contains rather more electronics than
a PC04. It's possible to turn a PC05 into a PC04 by removing some of the
flip-chip cards (including the 3 'specials', addiong an M113 (I think) and
doing a bit of wire-wrapping. I did this, having got a PC05, an PC8E
interface, plenty of other Unibus paper tape readers and interfaces but no
other paper tape system for the PDP8/e.
What machine does the OP want to use it with? Going o nthe 'minimum
number of errors to make it consistent', I assumed he simply meant Omibus
rahter than Unibus, and wants the PDP8/e compatible one.
-tony
Paul
On 8/12/08, Marden P. Marshall <mardy at voysys.com> wrote:
Does anyone have a DEC PC04 paper tape reader/punch that they would be
interested in letting go? I'm also looking for the matching PC8-E (M840)
UNIBUS controller card.
Thanks,
-Mardy
4:52 p.m.
On Aug 15, 2008, at 4:27 PM, Tony Duell wrote:
Yes, I did mean to say "OMNIBUS" as it is going into a PDP-8/e.
-Mardy
I think the M840 is the PDP8 controller. I don't remember the
Unibus part
number, but I should have one.
It is, that's why it's the PC8E (fits the Omnibus of the PDP8/e,
amongst
others).
The unibus controller is an PC11 (I forget the M-number). But the
pumch/reader for that is a PC05, and contains rather more
electronics than
a PC04. It's possible to turn a PC05 into a PC04 by removing some of
the
flip-chip cards (including the 3 'specials', addiong an M113 (I
think) and
doing a bit of wire-wrapping. I did this, having got a PC05, an PC8E
interface, plenty of other Unibus paper tape readers and interfaces
but no
other paper tape system for the PDP8/e.
What machine does the OP want to use it with? Going o nthe 'minimum
number of errors to make it consistent', I assumed he simply meant
Omibus
rahter than Unibus, and wants the PDP8/e compatible one.
-tony
Paul
On 8/12/08, Marden P. Marshall <mardy at voysys.com> wrote:
Does anyone have a DEC PC04 paper tape reader/punch that they
would be
interested in letting go? I'm also looking for the matching PC8-E
(M840)
UNIBUS controller card.
Thanks,
-Mardy
5:16 p.m.
Speaking of the PC-04 Paper Tape Reader/Punch, I have one for my PDP 8/e system, but one
of the ten phototransistors in the monolithic array is shorted, making it pretty useless
for reading tapes. It punches tapes fine.
There are ten phototransistors because eight are used for each of the channels of the
tape, one is used to sense the feed holes for clocking purposes, and the last is a
"end of tape" sensor. Unfortunately, since the phototransistors are in a
monolithic (single) package, I can't just replace the bad phototransistor or
re-arrange them to take the "tape out" one (which I could manage wtihout, I
suppose) and use it to replace the bad channel phototransistor.
The small pull-through tape reader that someone mentioned being sold on eBay by
"mikesdavis" uses a very similar phototransistor array to that in the PC-08, but
only has 9 phototransistors instead of 10.
Anyone out there have any idea where I could lay hands on a 10 transistor array just like
the one on the OAE "clone" that was on eBay (except with 10 transistors instead
of 9), I think that it'd work as a pin-for-pin replacement for the bad one in my
PC-04. OSRAM seems to make these, as I've found datasheets, but they won't even
talk to me, and I can't find any retailers that seem to stock this item.
Any help would be most appreciated.
Rick Bensene
8 p.m.
Rick Bensene wrote:
The small pull-through tape reader that someone
mentioned being sold on eBay by "mikesdavis" uses a very similar phototransistor
array to that in the PC-08, but only has 9 phototransistors instead of 10.
I thought Mike was making his own using surface-mount phototransistors,
rather than a monlithic array.
Eric
8:04 p.m.
On Friday 15 August 2008 20:00, Eric Smith wrote:
Rick Bensene wrote:
I have a bunch of phototransistors, salvaged from scrapping VCRs, each of
which has at least two (usually more) in there, if anybody needs some...
--
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
The small pull-through tape reader that someone
mentioned being sold on
eBay by "mikesdavis" uses a very similar phototransistor array to that in
the PC-08, but only has 9 phototransistors instead of 10.
I thought Mike was making his own using surface-mount phototransistors,
rather than a monlithic array. 
16 Aug
16 Aug
4:52 a.m.
Rick Bensene wrote:
Speaking of the PC-04 Paper Tape Reader/Punch, I have
one for my PDP 8/e system, but one of the ten phototransistors in the monolithic array is
shorted, making it pretty useless for reading tapes. It punches tapes fine.
There are ten phototransistors because eight are used for each of the channels of the
tape, one is used to sense the feed holes for clocking purposes, and the last is a
"end of tape" sensor. Unfortunately, since the phototransistors are in a
monolithic (single) package, I can't just replace the bad phototransistor or
re-arrange them to take the "tape out" one (which I could manage wtihout, I
suppose) and use it to replace the bad channel phototransistor.
Read the tape, flip it upside down, read it again, flip the bits, merge.
Gordon
17 Aug
17 Aug
2 a.m.
Speaking of
the PC-04 Paper Tape Reader/Punch, I have one for my PDP
8/e system, but one of the ten phototransistors in the monolithic
array is shorted, making it pretty useless for reading tapes.
Read the tape, flip
it upside down, read it again, flip the bits,
merge. 
18 Aug
18 Aug
4:47 a.m.
On Sun, Aug 17, 2008 at 02:00:02AM -0400, der Mouse wrote:
I'm moderately sure that the paper tape I used back when I had a PDP-8
was not symmetric in the way needed here - the line of feed/timing
holes was not on the centreline of the tape.
You are remembering correctly - they are not.
*But*, you could read the tape one way, flip it _and_ read it backwards.
Syncing up the two passes is just an exercise for the student ;-)
Personally, my PC04 is the primary load device for one of my PDP-8/Ls.
I'd be hurting if I lost a phototransistor - the SMT idea sounds handy.
What I'm more worried about is a spare bulb - It's a "festoon" bulb
(the kind commonly used for older automobile dome lights - it looks
like a large AGC-type glass fuse, with an axial filament), but trying
to cross it with a modern one from Osram or others has drawn a blank
for me. Has anyone found a modern substitute?
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 18-Aug-2008 at 08:40 Z
South Pole Station
PSC 468 Box 400 Temp -81.8 F (-63.2 C) Windchill -126.1 F (-87.8 C)
APO AP 96598 Wind 14.6 kts Grid 31 Barometer 668.9 mb (11050 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
Speaking of the PC-04 Paper Tape Reader/Punch, I have
one for my PDP
8/e system, but one of the ten phototransistors in the monolithic
array is shorted, making it pretty useless for reading tapes.
Read the tape, flip
it upside down, read it again, flip the bits,
merge.
9:11 a.m.
> I'm moderately sure that the paper tape I used
back when I had a
> PDP-8 was not symmetric in the way needed here - the line of
> feed/timing holes was not on the centreline of the tape.
You are remembering correctly - they are not.
*But*, you could read the tape one way, flip it _and_
read it
backwards. Syncing up the two passes is just an exercise for the
student ;-)
Yes, but you have to flip it end-for-end, not side-for-side, and then,
each row of holes is read with the same sensor on each pass. This
means that it won't help a bit with the "dead phototransistor" problem.
What I'm more worried about is a spare bulb -
[...] modern
substitute?
High-brightness LEDs? Very very far from original, but if you value
working over original....
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse at rodents-montreal.org
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
12:23 p.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
That style lamp is still readily available over
here (UK) as a car spare
used usually for number plate lights, my Fiat uses them.
What's the voltage ?, the available type are obviously 12V.
I have a paper tape sensor head taken off a reader for an SDS9300 system, 8
track (5 sprocket 3), if its of any use.
Best regards,
Mike Hatch
Web - www.soemtron.org
Email - mike at soemtron.org
Looking for a PDP-7 (some hope!)
----- Original Message -----
From: "Ethan Dicks" <ethan.dicks at usap.gov>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, August 18, 2008 9:47 AM
Subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
> On Sun, Aug 17, 2008 at 02:00:02AM -0400, der Mouse wrote:
>> >> Speaking of the PC-04 Paper Tape Reader/Punch, I have one for my PDP
>> >> 8/e system, but one of the ten phototransistors in the monolithic
>> >> array is shorted, making it pretty useless for reading tapes.
>> > Read the tape, flip it upside down, read it again, flip the bits,
>> > merge.
>>
>> I'm moderately sure that the paper tape I used back when I had a PDP-8
>> was not symmetric in the way needed here - the line of feed/timing
>> holes was not on the centreline of the tape.
>
> You are remembering correctly - they are not.
>
> *But*, you could read the tape one way, flip it _and_ read it backwards.
> Syncing up the two passes is just an exercise for the student ;-)
>
> Personally, my PC04 is the primary load device for one of my PDP-8/Ls.
> I'd be hurting if I lost a phototransistor - the SMT idea sounds handy.
>
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
> (the kind commonly used for older
automobile dome lights - it looks
> like a large AGC-type glass fuse, with an axial filament), but trying
> to cross it with a modern one from Osram or others has drawn a blank
> for me. Has anyone found a modern substitute?
>
> -ethan
>
>
> --
> Ethan Dicks, A-333-S Current South Pole Weather at 18-Aug-2008 at
> 08:40 Z
> South Pole Station
> PSC 468 Box 400 Temp -81.8 F (-63.2 C) Windchill -126.1 F (-87.8
> C)
> APO AP 96598 Wind 14.6 kts Grid 31 Barometer 668.9 mb (11050
> ft)
>
> Ethan.Dicks at usap.gov
> http://penguincentral.com/penguincentral.html
>
>
4:14 p.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
That style lamp is still readily available over
here (UK) as a car spare
used usually for number plate lights, my Fiat uses them.
What's the voltage ?, the available type are obviously 12V.
4:57 p.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
Tony Duell wrote:
Not 'obviosuly'....
Old cars used 6V electrics, lorries, etc use 24V (still, AFAIK). Good car
parts shops can often get 6V and 24V bulbs as a result, which are used in
classic computers. For example, most of my Trend paper tape readers use a
12V 21W bulb, a very standard car bulb sold everywhere. But at leat one
uses a 24V 24W bulb. It took some finding, but a commerical vehicles
parts place had it in stock.
Hah. Don't mix them up.
I bought 24V "corn" bulbs for my RL02 panel lamps (the ones that came
out were rated for 18V, so I figured I'd rather have dimmer and cooler
than hotter and brighter). Then a panel lamp went on my car dashboard,
*months* later. "Aha!" I thought, "I've got spare bulbs..."
Stuck one
in, and hmm, why is it so dim? D'oh.
Gordon
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
That style lamp is still readily available over
here (UK) as a car spare
used usually for number plate lights, my Fiat uses them.
What's the voltage ?, the available type are obviously 12V. 
6:14 p.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
On 18/08/2008 21:57, Gordon JC Pearce wrote:
I bought 24V "corn" bulbs for my RL02 panel
lamps (the ones that came
out were rated for 18V, so I figured I'd rather have dimmer and cooler
than hotter and brighter).
Actually they're supposed to be 14V. I guess the person who replaced
them before you, thought the same way you did :-)
--
Pete Peter Turnbull
Network Manager
University of York
19 Aug
19 Aug
5:42 a.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
By obviously I meant the usually found ones are 12V.
6V can be obtained, older volkswagens etc, lorries, coaches have a lot of
24V, but some have moved upto 48V and I've heard of some 72V rails in
commercial vehicles although rare.
The readers we had were very particular about the filament, it had to be
straight and even, any kinks, bright spots or different filament styles
would not work reliably.
Mike
Web - www.soemtron.org
Email - mike at soemtron.org
Looking for a PDP-7 (some hope!)
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Monday, August 18, 2008 9:14 PM
Subject: Re: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
Not 'obviosuly'....
Old cars used 6V electrics, lorries, etc use 24V (still, AFAIK). Good car
parts shops can often get 6V and 24V bulbs as a result, which are used in
classic computers. For example, most of my Trend paper tape readers use a
12V 21W bulb, a very standard car bulb sold everywhere. But at leat one
uses a 24V 24W bulb. It took some finding, but a commerical vehicles
parts place had it in stock.
-tony
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
That style lamp is still readily available over
here (UK) as a car spare
used usually for number plate lights, my Fiat uses them.
What's the voltage ?, the available type are obviously 12V. 
11:32 a.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
On 19 Aug 2008 at 10:42, Mike Hatch wrote:
By obviously I meant the usually found ones are 12V.
6V can be obtained, older volkswagens etc, lorries, coaches have a lot of
24V, but some have moved upto 48V and I've heard of some 72V rails in
commercial vehicles although rare.
Aren't most "12V" automotive lamps really rated for either 13.6 or
14.4 volts? I know this is a nit, but I seem to remember that the
automotive types are slightly different from normal 12.6V "pilot"
lamps, even when they share the same base.
Festoon bulbs are also found in marine lighting and can be obtained
in halogen configurations in 12 and 24 volt varieties.
What's the response of the sensor? IR or something in the visible
range? I've seen white-LED replacements, but if it's an IR sensor,
that probably isn't going to do much good.
Cheers,
Chuck
11:45 a.m.
On Aug 19, 2008, at 11:32 AM, Chuck Guzis wrote:
On 19 Aug 2008 at 10:42, Mike Hatch wrote:
Guys, two words "thread hijacking".
-Mardy
By obviously I meant the usually found ones are
12V.
6V can be obtained, older volkswagens etc, lorries, coaches have a
lot of
24V, but some have moved upto 48V and I've heard of some 72V rails in
commercial vehicles although rare.
Aren't most "12V" automotive lamps really rated for either 13.6 or
14.4 volts? I know this is a nit, but I seem to remember that the
automotive types are slightly different from normal 12.6V "pilot"
lamps, even when they share the same base.
Festoon bulbs are also found in marine lighting and can be obtained
in halogen configurations in 12 and 24 volt varieties.
What's the response of the sensor? IR or something in the visible
range? I've seen white-LED replacements, but if it's an IR sensor,
that probably isn't going to do much good.
Cheers,
Chuck
11:49 a.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
Mike Hatch wrote:
Looking for a PDP-7 (some hope!)
Have you seen this page ?
A pdp 4 in FPGA.
http://homepage.mac.com/dgcx/pdp4x/
12:30 p.m.
New subject: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
I have thanks, I believe there is an implementation of a 7 as well
somewhere.
Best regards,
Mike Hatch
Web - www.soemtron.org
Email - mike at soemtron.org
Looking for a PDP-7 (some hope!)
----- Original Message -----
From: <bfranchuk at jetnet.ab.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, August 19, 2008 4:49 PM
Subject: Re: [personal] Re: WTB: DEC PC04 Paper Tape Reader/Punch
Mike Hatch wrote:
Looking for a PDP-7 (some hope!)
Have you seen this page ?
A pdp 4 in FPGA.
http://homepage.mac.com/dgcx/pdp4x/
18 Aug
18 Aug
1:55 p.m.
From: "Ethan Dicks"
*But*, you could read the tape one way, flip it _and_
read it backwards.
Syncing up the two passes is just an exercise for the student ;-)
Alas, that wouldn't help with the bad phototransistor.
Personally, my PC04 is the primary load device for one
of my PDP-8/Ls.
I'd be hurting if I lost a phototransistor - the SMT idea sounds handy.
It sounds interesting to me too. Are there detailed specs for the
phototransistor array, or would I have to take my PC04 apart and
measure everything?
Some PC04 seem to need 10 phototransistors, while others leave the
tenth phototransistor unconnected. I haven't looked at how hard it
would be to convert the former to the latter. I suspect the sprocket
sensor could be made to sense the out-of-tape condition, since the
out-of-tape detection is based on requiring a pulse train.
What I'm more worried about is a spare bulb -
It's a "festoon" bulb
(the kind commonly used for older automobile dome lights - it looks
like a large AGC-type glass fuse, with an axial filament), but trying
to cross it with a modern one from Osram or others has drawn a blank
for me. Has anyone found a modern substitute?
Well, there's this sort of thing:
http://www.ledtronics.com/ds/fes001/
The tricky part for these seems to be getting ones that will work well
on 5V.
Isn't it basically exactly an old-school 6V automotive dome light?
I wasn't able to find a part number for the original, so I don't know
the original dimensions, either. There seem to be at least a couple
of common lengths.
Curious that the documentation doesn't suggest stocking a replacement,
or even tell you what part to use.
If it's DEC part number 12-04903, then that's available here:
http://www.atlantalightbulbs.com/ecart/nw012104/PHILIPS6411LAMP10W12V.htm
Vince
6:44 p.m.
On Mon, Aug 18, 2008 at 10:55:14AM -0700, Vincent Slyngstad wrote:
I have no idea. I was just referencing a recent post about someone
mentioning making a functional reconstruction.
Interesting option.
From: "Ethan Dicks"
Ah, yes... I didn't do the right transformation in my head.
*But*, you could read the tape one way, flip it
_and_ read it backwards.
Syncing up the two passes is just an exercise for the student ;-)
Alas, that wouldn't help with the bad phototransistor. Personally, my
PC04 is the primary load device for one of my PDP-8/Ls.
I'd be hurting if I lost a phototransistor - the SMT idea sounds handy.
It sounds interesting to me too. Are there detailed specs for the
phototransistor array, or would I have to take my PC04 apart and
measure everything? What I'm more worried about is a spare bulb -
It's a "festoon" bulb
Well, there's this sort of thing:
http://www.ledtronics.com/ds/fes001/
The tricky part for these seems to be getting ones that will work well
on 5V. Isn't it basically exactly an old-school 6V
automotive dome light?
It was a dome light, but I'm not certain about the voltage right now.
It's entirely possible it's a 6V bulb derated to 5V, but I'm not sure.
I wasn't able to find a part number for the
original, so I don't know
the original dimensions, either. There seem to be at least a couple
of common lengths.
I remember that being my experience as well. Fortunately, I _do_ have
a bulb, so I can measure it.
Curious that the documentation doesn't suggest
stocking a replacement,
or even tell you what part to use.
Yeah; I don't remember ever running across any official docs about it.
The best I recall is finding an Osram part number _somewhere_, but
not being able to find that bulb in their modern catalog and no
crossreference.
If it's DEC part number 12-04903, then that's
available here:
http://www.atlantalightbulbs.com/ecart/nw012104/PHILIPS6411LAMP10W12V.htm
Thanks; that certainly resembles the original, but, again, I'm not
sure about the voltage.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 18-Aug-2008 at 22:40 Z
South Pole Station
PSC 468 Box 400 Temp -84.5 F (-64.7 C) Windchill -123.0 F (-86.1 C)
APO AP 96598 Wind 10.0 kts Grid 56 Barometer 669.8 mb (11015 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
7:45 p.m.
From: "Ethan Dicks" <ethan.dicks at usap.gov>
On Mon, Aug 18, 2008 at 10:55:14AM -0700, Vincent
Slyngstad wrote:
I did check that it's being run from +5V through a 2 ohm 10W potentiometer.
So I thought a 6V automotive dome light would be about right.
Isn't it basically exactly an old-school 6V
automotive dome light?
It was a dome light, but I'm not certain about the voltage right now.
It's entirely possible it's a 6V bulb derated to 5V, but I'm not sure.
The best I recall is finding an Osram part number
_somewhere_, but
not being able to find that bulb in their modern catalog and no
crossreference.
> If it's DEC part number 12-04903, then that's available here:
> http://www.atlantalightbulbs.com/ecart/nw012104/PHILIPS6411LAMP10W12V.htm
If you have the Osram part number, we can check that it is or is not the
12-04903, which is Osram #6411. That's the lowest voltage Osram bulb I
found referenced in the 9/1/70 version of the DEC Spare Parts Reference,
Volume II, section 12 (purchased vendor items). The thing that is fishy
about it is that it seems to be a 12V bulb. The drawings clearly show
the bulb being driven from +5V, so it seems that a 12V bulb would have
been serious overkill for that application. Maybe that's why they
thought they'd never need replacement :-).
Vince
19 Aug
19 Aug
5:28 a.m.
New subject: [personal] **JUNK** Re: WTB: DEC PC04 Paper Tape Reader/Punch
The thing that is fishy
about it is that it seems to be a 12V bulb. The drawings clearly show
the bulb being driven from +5V, so it seems that a 12V bulb would have
been serious overkill for that application.
From my reccolection they were seriousley under run and
very rarely
replaced, they were not "bright" as you would expect a lamp
to be.
Mike
Web - www.soemtron.org
Email - mike at soemtron.org
Looking for a PDP-7 (some hope!)
----- Original Message -----
From: "Vincent Slyngstad" <vrs at msn.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, August 19, 2008 12:45 AM
Subject: [personal] **JUNK** Re: WTB: DEC PC04 Paper Tape Reader/Punch
From: "Ethan Dicks" <ethan.dicks at
usap.gov>
On Mon, Aug 18, 2008 at 10:55:14AM -0700, Vincent
Slyngstad wrote:
I did check that it's being run from +5V through a 2 ohm 10W
potentiometer.
So I thought a 6V automotive dome light would be about right.
Isn't it basically exactly an old-school 6V
automotive dome light?
It was a dome light, but I'm not certain about the voltage right now.
It's entirely possible it's a 6V bulb derated to 5V, but I'm not sure.
The best I recall is finding an Osram part number
_somewhere_, but
not being able to find that bulb in their modern catalog and no
crossreference.
> If it's DEC part number 12-04903, then that's available here:
> http://www.atlantalightbulbs.com/ecart/nw012104/PHILIPS6411LAMP10W12V.htm
If you have the Osram part number, we can check that it is or is not the
12-04903, which is Osram #6411. That's the lowest voltage Osram bulb I
found referenced in the 9/1/70 version of the DEC Spare Parts Reference,
Volume II, section 12 (purchased vendor items). The thing that is fishy
about it is that it seems to be a 12V bulb. The drawings clearly show
the bulb being driven from +5V, so it seems that a 12V bulb would have
been serious overkill for that application. Maybe that's why they
thought they'd never need replacement :-).
Vince
18 Aug
18 Aug
4 p.m.
I'm
moderately sure that the paper tape I used back when I had a PDP-8
was not symmetric in the way needed here - the line of feed/timing
holes was not on the centreline of the tape.
You are remembering correctly - they are not.
*But*, you could read the tape one way, flip it _and_ read it backwards.
Syncing up the two passes is just an exercise for the student ;-)
Personally, my PC04 is the primary load device for one of my PDP-8/Ls.
I'd be hurting if I lost a phototransistor - the SMT idea sounds handy.
What I'm more worried about is a spare bulb - It's a "festoon" bulb
(the kind commonly used for older automobile dome lights - it looks
like a large AGC-type glass fuse, with an axial filament), but trying
to cross it with a modern one from Osram or others has drawn a blank
for me. Has anyone found a modern substitute?
Is it particularly critical? I can't even remember what the voltage is
supposed to be, but assuming you can find something of the right voltage
and about the same wattage it should work.
Now, finding replacement bulbs for an HP2748 is another matter (that
reader has an individual 'grain of wheat' bulb for each track, all 10 (8
data tracks, feed track, reference lamp) in series across a 45V supply.
-tony
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