>Tim wrote:
>> And by this point in time ferroresonant transformers were also being
>> dropped in by folks who weren't happy with the original supply, either.
>> Having used a large variety of S-100 boxes, far and away my favorite
>> power supplies are ones with ferroresonant transformers.
>I've been told that one shouldn't plug anything using a ferroresonant
>transformer into a UPS. Perhaps someone who knows more about the
>characteristics of ferroresonant transformers (and UPSes) can explain why,
>or refute the claim.
Ferroresonant transformers really really want sine waves as input.
Many UPS's put out square waves, or slightly shaped square waves.
There are many high-frequency harmonics in a square wave, and these
disrupt the careful LC-resonance-at-saturation regulation mechanism.
Not only do ferroresonant transformers want sine waves, they want
sine waves of a specific frequency. I've never tried running a 60Hz
unit at 50Hz, but I do know from hard experience what happens at
400 Hz :-(.
There are UPS's that do put out nice sine waves, but these aren't all
that commonly found.
>(*) The only modern thing, anyhow. Did DEC use ferroresonant transformers in
>any of their machines?
DEC computers from 1970 onwards typically used switching supplies for
all high-current supplies, though there are usually some low-current
supplies with linear regulators. (There are some exceptions, such as
the "large" 8/E using a linear supply while the "small" 8/F used a
switching supply)...
DEC did sell ferroresonant line conditioners (some of them quite large;
one that I passed by took 440VAC 3-phase in and had about 70 15 amp
circuits out), but these came before the computer.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology Voice: 301-767-5917
7328 Bradley Blvd Fax: 301-767-5927
Bethesda, MD, USA 20817
I may be mixing up lists here (must get that procmail filter setup) but I
think someone was looking for a copy of Dos (MS) ver 1 or 1.1. If so let
me know, I have a disk image of most old versions of IBM/MS dos stored
away. Its useless on a hard disk system though as it has no support for
them.
Just let me know...
Colan
But what about the metal parts? Those aren't any cheaper...but you're
giving me ideas. I saw a show once on CNN about a guy at Lawrence
Livermore who is building robot bugs out of computer parts. They are
powered by neural networks. He can even pull off a couple of legs
and they'll still work. BTW, where do all of those researchers get
neural network chips?
>
>I remember when I was a kid I was dreaming about building robots and
using
>computers to control them, but all the parts and expecially the
computers
>were too expensive. I had one design based on a //c, but this was
around
>1986 when the //c was still relatively new.
>
>Today, a kid could go to a thrift store and buy all manner of
salvageable
>computer parts, including printers (to get the steppers and gears out
of),
>disk drives (for the motors and gear shafts) and of course the
computers
>to control their projects with easy to use languages built in, all for
>just a few bucks.
>
>An entire robot could be built for under $100 with thrift store and
flea
>market parts. It could include a fairly powerful and easy to program
>"brain" in the form of a Commodore 64, a Tandy CoCo, even an Apple ][
>board. This stuff is everywhere and extremely simple to hack.
>
>Man, I wish I was a kid again!
>
>Sam Alternate e-mail:
dastar(a)siconic.com
>-------------------------------------------------------------------------------
>Ever onward.
>
> September 26 & 27...Vintage Computer Festival 2.0
> See http://www.vintage.org/vcf for details!
> [Last web site update: 09/12/98]
>
>
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
I just saw this posting - a free Fortune 32:16 in Utah!
>I have this old, but functional, Fortune 32:16 computer system that
>I'm trying to get rid of. I hate throwing away working hardware, so I
>wanted to see if someone else could give it a good home before I'm
>forced to dispose of it by other means.
>
>Details at http://www.xmission.com/~skb/fortune.html
(I want it but my wife would kill me.)
Bob Stek
bobstek(a)ix.netcom.com
Saver of lost SOLs
installing the mathco will wont speed up anything EXCEPT for programs that USE
it. i bought an xt that had a 16 bit vga card in it. i dont know if every 16
bit vga card works in an 8bit slot, but i guess it's worth a try anyway.
david
In a message dated 98-09-18 21:14:47 EDT, you write:
<< I've got an Intel Inboard card, but mounted in a 5150 with a Plus
hardcard.
I've also been searching for the piggyback with no luck so far. Would adding
a 387 co-processer speed applications up significantly ? I'm also on the
lookout for an 8-bit VGA card for this set-up. I have a 16-bit card with a
switch for either 9 or 15 pin connectors. I don't suppose this would work
in the 8-bit 5150 would it ? I know some 16-bit cards will work in an 8-bit.
ciao larry >>
I'm going to have to refresh and improve my programming skills in RPG
(not role playing games RPG) for the IBM AS400 system and am in search
of good books on general RPG as well as RPG400 specific programming,
>from a basic level to mid/advanced. Haven't even programmed in RPG in 6
or 7 yrs so I need to go way back to the beginnings.
___________________________________________________
Russ Blakeman, aka "Pooter Fixer"
Email: rhblake(a)bbtel.com or rhblake(a)bigfoot.com
Website: http://members.xoom.com/pooterfixer/
___________________________________________________
> > That doesn't always work. luckily, there's one every year pretty
nearby.
> > That's where I got my Tandy 1000 with 4 LPT ports (I don't know how
they
> > all work, but they do, and I'm not gonna touch 'em). I was planning on
> > using it as the controller, and hooking up printer guts and making it
work
> > by sending line feeds and spaces, and things like through BASIC.
>
> If you go to Doug Jones' page at the University of Iowa:
>
> http://www.cs.uiowa.edu/~djones
>
> he has a link to some documentation and source code for gutting out
> floppy drives so that you can control the stepper and spin the drive
> motor.
The link doesn't work.
--
-Jason
(roblwill(a)usaor.net)
ICQ#-1730318
>I don't have a variac or anything and don't have the time or money to get
>one, but I need to bring up an IMSAI power supply that probably hasn't
>been powered in over a decade perhaps. What can I do to warm up the caps
>and transformer before bringing it fully online? Anything?
The "poor man's" substitute for a variac has always been a 120V light
bulb in series with the AC. For something like an unloaded IMSAI
power supply, a small (15W or so) bulb might be best for starters.
That said, the capacitors are standard off-the-shelf items, and if you
do blow 'em up, just put in some new ones.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology Voice: 301-767-5917
7328 Bradley Blvd Fax: 301-767-5927
Bethesda, MD, USA 20817
< I've got a question I've been meaning to ask for a long time. Does Bill
< Gates know how to program? If my memory serves me correct he knew how t
< progam in BASIC back in the late 70's, his buddy Paul Allen knew machin
< language.
No, he knew how to code asm for a BASIC interpreter. I don't know when he
stopped coding but many say the basic and OS used in the tandy 100 was the
last effort he had a direct hand in.
Allison
< And by this point in time ferroresonant transformers were also being
< dropped in by folks who weren't happy with the original supply, either.
< Having used a large variety of S-100 boxes, far and away my favorite
< power supplies are ones with ferroresonant transformers.
Compupro and ECT come to mind... I have both and they are really well
engineerd bent metal.
Allison
