At 01:42 AM 2/23/2007, Hex Star wrote:
>Indeed...and I was criticized for posting a OT thread on this list before
>and here comes a OT thread that is openly discussed...what gives??? Why was
>I flamed while this guy is not? I just don't get it...:(
Tim's a well-respected guru so he gets more slack than a newcomer
behind an alias. :-) To play devil's advocate, it is more relevant
than many OT posts. Longevity of disk drives is a significant
concern to computer collectors, no? The study is about contemporary
drives that may have very different parameters than old drives, though.
But it's always interesting to see rules of thumb and "common wisdom"
pushed aside by data and analysis.
- John
Just for illustration; our electricity supply here in England comes up
>from the Fawley power station near Southamption at 132kV on pylons. It
goes to a substation at Thatcham about two miles distant. Its stepped
down to 11kV and distributed over a radius of up to five miles on wooden
poles with a metal T bar on top. In some areas its three phase and
others not. Now comes the aforementioned transformer. Its normally
mounted on one of the 11kV poles. It steps down to 235v and feeds a fair
number of houses. Our supplies are fused at 60A or 100A at each house.
Rod Smallwood
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 22 February 2007 21:15
To: cctalk at classiccmp.org
Subject: Re: New DEC museum entry :D
>
> Tony Duell wrote:
> > (there are no 'pole pigs' over here)
>
> Is that always true? Sometimes on rural roads with just one or two
> houses (and also individually on farms) I've seen pole-mounted
> transformers and wondered what their function is - I'd assumed they
> were step-down transformers from overhead line voltage (several KV I'd
> guess) to 240VAC. Or do they do some completely different job?
I think you're absoluately right. But they normally supply more than
just one house, don't they?
OK, I was a little too definite in my original statement. I should have
said 'Pole pigs are rarely used in the UK, in towns/cities (at least),
many houses are supplied from the same transformer'.
-tony
From: "Chuck Guzis" <cclist at sydex.com>
Subject: Re: New DEC museum entry :D
<snip>
>And a question for the US experts. On a 120v circuit, will a $6.00
>GFI detect a leak between neutral and ground? Or is the detection
>circuitry only on the high side of the line?
As mentioned by several others, GF(C)Is detect an imbalance between
hot and neutral and do not in fact care about ground at all. Since the
neutral is normally bonded to ground at the main panel, it would require
considerable current in the neutral to generate a detectable voltage
difference between neutral and ground at the receptacle; in the unlikely
event that the neutral is not at ground potential a GFCI would still trip
on a fault.
In fact, if you have to replace one of the unobtainium 2-prong ungrounded
receptacles in an old house wired with knob & tube (or the '50s era 2-wire NM
non-metallic sheathed), replacing it with a GFCI receptacle will give protection
similar to a grounded outlet (although of course running a ground wire back to
the panel is preferable, since an internal short or leakage will not be detected
until there is an external path to ground, and noise suppression filters will be
ineffective).
The "bedroom GFCI"s that Ethan mentioned are actually Arc-fault interrrupters,
required by most jurisdictions for the last 4 or 5 years in bedroom circuits
because neither a circuit breaker nor a GFCI will trip on an arcing short or
connection (the cause of many if not most residential electrical fires) if the
current is less than the breaker rating.
mike
Don't see many Wang minis going around. No pictures, but the
description lists it as containing a reasonable set of cards. I would
contact the seller directly before bidding.
Item # 160088328422
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
On 22 Feb, 2007, at 18:03, cctalk-request at classiccmp.org wrote:
>
> Message: 14
> Date: Thu, 22 Feb 2007 08:22:15 -0600
> From: Jules Richardson <julesrichardsonuk at yahoo.co.uk>
> Subject: Re: New DEC museum entry :D
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Message-ID: <45DDA717.80406 at yahoo.co.uk>
> Content-Type: text/plain; charset=ISO-8859-15; format=flowed
>
> Tony Duell wrote:
>> (there are no 'pole pigs' over here)
>
> Is that always true? Sometimes on rural roads with just one or two
> houses (and
> also individually on farms) I've seen pole-mounted transformers and
> wondered
> what their function is - I'd assumed they were step-down
> transformers from
> overhead line voltage (several KV I'd guess) to 240VAC. Or do they
> do some
> completely different job?
>
I live on a farm, we have a three phase step down transformer on a
pole in our field.
It steps down from 11,000 volts to 240/440 volts. I guess the 11,000v
is across
phases as there is no neutral conductor. We used to have a two wire
supply to the
pole with a 240-0-240 transformer. Then the incoming cloth covered
wiring from the
pole caught fire. Couldn't do much - it was before it reached any of
our fuse boxes
or even the meters, even pulling out the 'company' fuses would not
have isolated
it. We put it out but ran out of powder extinguishers. The fire
brigade took over
half an hour to arrive (it was in January and it was snowing). They
went into the
house with breathing apparatus and just saved the house. Everything
was covered
in congealed PVC, some decorative candles had completely melted and
they said
another couple of minutes and we would have lost the house. They sat
on the stairs
for four hours, putting out each new fire in the distribution board
until the electricity
company turned up and pulled the 1000 Amp fuses on the pole above the
barbed
wire. The fire brigade were about to leave when my mother pointed out
some smoke
coming from the wall. The upper storey is timber framed and the
woodwork behind
the distribution board was alight. They ripped off the Kent peg tiles
and we finished
the day with a big hole in both inner and outside surfaces of the
wall. Next day the
electricity company turned up to read the meters, I said hold your
hand out, and I
dropped a few loose brass wheels which had had numbers painted on
them into
his hand and pointed out that was all that was left of the meters.
The best guess we could get from anyone was that it was a mis-matched
load over
the two 'phases' (actually 180 degrees apart), and that the neutral
wire could not
cope. Later on we got the company apparatus moved into a redundant
chimney
where it could catch light without doing much damage and I paid 400
pounds
to have an extra wire put on the overhead supply to the pole and the
transformer
upgraded to a three phase unit, so I could power my lathe, mill,
shaper, surface
grinder, pillar drill and my mainframe computer from the mains
instead of using
a generator.
Roger Holmes.
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
> > process-control equipment. I helped get me through college by
> > working as an instrumentation technician summers. Really primitive
>
> I think the main problem is that it's difficult to recreate enough of the
> 'process' at home to be able to use this equipment, so it would be a
> static collection. Of course some meaursing instruments can be used for
> other purposes, but then people do collect measuring instruments.
That's true for stuff that is built or irreversibly programmed for a particular application, but there were modular systems as well, which could be used for quite a lot of things. The 'process' can often also be scaled for a demonstration model - University has a nice display of a PLC running a model 'production line' built from Fischertechnik:
http://www.rt.eei.uni-erlangen.de/FGdes/index_en.html
As I happened across process control stuff, some of it inevitably found its way into my collection, namely:
-some Simatic N boards (eurocard form factor, DIN connectors) which fit into a small rack and realize simple logic functions like gates and flip-flops (several per card) up to counters and comperators. The person I got them from originally intended to implement some security functions for his model railway with them, reducing the possibility of accidental crashes, but now controls everything by computer.
-Simatic C1 trainer set consisting of a piece of DIN top-hat rail mounted on a wooden base and stuffed with "blocks" (functions like the boards; sized like circuit breakers, connectors on the front) together with a 24V supply and a switches/indicators panel, complete with a bunch of wires for setting up the connections. I had that wired up as a 4-bit binary counter when they wanted a prop with lights blinking in a clever fashion for our A-level party.
-Simatic S4, microprocessor based PLC (8086 I think?). It is programmed (either with a hand-held LCD device or with a luggable CP/M machine plus the appropriate software and interface)...by designing a Ladder Diagram or "Kontaktplan", a schematic of how you would implement the function you want with relays. The program is then stored in an EEPROM cartridge. I/O is also 24V DC, 230V AC modules were available. I tested it but don't know what to do with it yet; I thought about building a lights and switches panel and implementing a tic-tac-toe engine as a demonstration program.
-Sinumerik mate TG, a controller for CNC lathes. This is unfortunately incomplete, since I only have the electronics cabinet, but not the proprietary display unit which also incorporates the character and (I suppose) vector generator circuitry - It was originally there, but was junked before I realized I wanted the thing. I can only hope I'll ever find one again...used replacements are EUR 3000,- upwards.
Not much analog stuff here yet, unfortunately - apart frome some chart recorders by HP and Kipp & Zonen (Netherlands). The one HP is a two-channel recorder with fine hoses for ink distribution to the pens and rubber balls for priming - What do the cartridges look for those like? Can you still get them? (It came without.) The other HP is an analog x/y and x/t plotter with plugin slots for pre-amplifier and filter modules.
Don't have anything pneumatic or fluidic yet, althought I consider these technologies very interesting.
BTW: If somebody has analog control and/or CNC/PLC stuff floating around and wants it gone or swapped, we might try to work something out; I'm located in Germany and will be present at the VCFe 8.0, 28./29.04. in Munich.
Greetings,
--
Arno Kletzander
Stud. Hilfskraft Informatik Sammlung Erlangen
www.iser.uni-erlangen.de
"Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ...
Jetzt GMX TopMail testen: www.gmx.net/de/go/mailfooter/topmail-out
I've just posted ImageDisk 1.14 to the web site.
This is a minor update adding automatic processing of
IMD.CMD if it exists in the ImageDisk home directory at
startup (lets you customize IMD to your own preferences),
and the ability to easily run command files from the IMD
home directory.
Please let me know if you encounter any problems.
Dave
--
dave06a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.classiccmp.org/dunfield/index.html
Hi
I would have gladly taken it 'tware it not for the fact I'm in the UK.
I worked for DEC when Rainbows were current.
I had one mounted in the leg of a special desk made to take them.
It would have complemented my '91 Vax 4000 nicely.
Its a pity air freight has not gone the way of passenger air fares.
Oh well! one may turn up in the UK.
Rod Smallwood
-----Original Message-----
From: cctech-bounces at classiccmp.org
[mailto:cctech-bounces at classiccmp.org] On Behalf Of Bob Rosenbloom
Sent: 21 February 2007 20:51
To: General Discussion: On-Topic and Off-Topic Posts
Subject: DEC Rainbow PC100 available
Not my cup of tea but someone on this list may be interested. Please
contact Gary directly.
Bob
______________________________________________________________________
Bob,
Our stuff isn't really what I would call "vintage". It's a 1985 rainbow
pc100. about the only cool thing is that is is all complete including
documentation and mint condition. my wife worked for DEC at the time and
purchased it as a "state of the art" system......
if you know of anyone collecting these I can e-mail the original billing
statement which lists the whole system.
Gary Mathews
garym at quickbeam.com
I was emailing back & forth with a person who collects HP mini's and they
mentioned....
> Eventually, I'd like to put together a dual-processor realtime system
> similar to the Continental 2005A RTE configuration,
I responded...
> I've never even seen any reference
> to it. I'm extremely curious as to just what it is. Can you enlighten
> me at all about it?
He said...
Continental Airlines contracted HP to build a real-time system around
1970, and HP put together a dual-CPU system similar to a 2000A, with a
2116 and a 2114. HP advertised the hardware configuration itself (not
just the software) as the 2005A Real Time Executive. The Contential
configuration is dual-CPU, but the default 2005A configuration in the HP
catalog has only a 2116 and about half the peripherals of the
Continental configuration.
-------------------------
I have never heard of this Continental 2005A dual processor Real Time
Executive, especially as an official product. Does anyone have more
information?
Jay
