>
>Subject: Re: small valves
> From: "Bob Shannon" <bshannon at tiac.net>
> Date: Fri, 22 Apr 2005 19:00:24 -0400
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>I've not been into R/C stuff, but I am into 'submini' tubes.
>
>I recently built a 5-tube regenerative receiver for the 49 meter band using
>5678's for the 2 stage tuned RF amp, detector, and first audio amp. A 5676
>serves as the final audio driver.
Can you send me a schematic you used? I must have 20 of those, as well
as 1AD4 and 5672s. I was forturnate that someone gave me a bunch of them
and I've found them fun to play with. I've done a single tube regen (160m)
with it and stuffed in a small tin. I run it on an AA cell and three
9v batteries.
>This is my fourth tube based radio. A friend was joking that these
>recreations sould be known as 'bunker buddies' 1 thru 4, as they
>use no semiconductors at all.
>
;) I have several tube sets I've built as a result of parts being
avaiable. They are interesting to me. I started my career with
tube, hybrid and full solid state commercial two way (VHF/UHF) equipment
so this is retro for me. A different challenge than solid state,
fun none the less.
Allison
KB1GMX
It's been a *LONG* time since I had any of my Apple //'s running. I've got
the following:
Apple //+
2 or 3 Apple //e's
some Apple //c's, including 2 of the little greenscreen monitors
2 Apple //gs's (one has a SCSI adapter)
I've also got various floppy drives.
What I'm not sure of is the state of my software. Currently all of my 5.25"
Apple // software is on loan to a friend (I don't have much, it's only one
small box). I've got a bunch if //gs software, but I'm not sure where. I
also have a Powerbook 520c that I can use to read and write 3.5" ProDOS
floppies. I think I can also use it to make new System 6 floppies if I
can't find the ones I have.
I'm trying to figure out what on earth I should setup. My real goal is to
run the following game, on real hardware:
http://www.iosphere.net/%7eeric/wizardry/weeping_snows.htm
I'm guessing my best bet, from a space related point of view is to use one
of the //c's and the small monitor that goes with it. The question then
becomes, how on earth does one write emulator images back to real 5.25"
floppies these days? I'm guessing my best bet might be to setup a //gs long
enough to write the floppies. ISTR, there is a program to transfer them
over a serial line, but you need a boot floppy for the Apple // to start the
process (as well as a Super Serial card, which I believe is built into a
//c).
Zane
>I've done this briefly with my PowerMac 8500 back around 1997, which was
>where I came up with the idea. The 8500 has the advantage of being able to
>handle both NTSC and PAL signals (not sure what other Mac's succh as yours
>can handle).
The 6500 also did NTSC and PAL. Apple really only made one video input
setup, they just packaged it onto different cards for the different
machines.
Actually, I used to use my 6500 to convert PAL videos to NTSC. I used a
PAL VCR to feed the signal into the PowerMac, then played the video in
full screen mode, and connected its NTSC output to another VCR. It worked
quite well actually, and had the nice side effect of bypassing
macrovision as well (the 6500 acted as a TBC since its NTSC output wasn't
really outputting the source video, but rather an image of the computer
desktop that just happened to have the source video playing in full
screen).
-chris
<http://www.mythtech.net>
Hello fellow ClassicCmp'ers,
In my search for a good X terminal I have played some more with the
available options. I have looked at my hardware options (VS3100 or
VXT 2000 hardware), examined already-existing software options (EWS, VXT
and VXT EX), and considered constructing my own X terminal software
>from the 4.3BSD-Quasijarus kernel and MIT X11R4 or X11R5 X server.
Ultimately I was not satisfied with any of these options as a true
solution that would make me happy, any of those would be a temporary
kludge at best, so I have decided to take the radical approach:
I'm going to design and build my own X terminal, and I mean hardware.
I'll use PowerPC for the CPU and Linux for the OS. The CPU and OS
choices are driven by experience: I have worked for a company that
made PowerPC single-board computers and I know how to make one of those
critters. There I developed a ROM monitor for PowerPC with the look and
feel of a VAX console (>>> prompt, etc), and that's the ROM monitor I'm
going to use. I also maintained Linux/PPC for those boards at that company,
thus the experience deciding my OS choice. Also one of my friends has
worked at the same company together with me as a hardware engineer,
and I'll enlist his help on this package for the real "hard" hardware
aspects.
The X display consists of a screen, keyboard and mouse, and my choices
for these three are as follows: an off-the-shelf PCI video chip with
good XFree86 support for the screen, DEC LK201 for the keyboard, and
many options for the mouse, including DEC mice, PC serial mice and USB
mice. The server will be XFree86 modified to use the LK201 keyboard
instead of a PC one.
The use of LK201 keyboard is one design aspect I'm absolutely firm on.
I'm very partial to this keyboard, and an X terminal that uses an LK201
is precisely what I want and what I cannot get from any modern offerings.
The mouse is less critical to me: a mouse is a mouse. I do want a
classic workstation mouse with 3 buttons and no wheel, but I don't really
care if it's a DEC hockey puck or an old PC 3-button serial mouse.
That's why I want to support many options for the mouse. (Are there any
3-button sans-wheel USB mice?)
My tentative PowerPC CPU choice is MPC8250. It has a traditional 603e
core with integrated memory controller, PCI interface (on which I'll hang
the video and USB chips) and communication module (which I'll use for
Ethernet and serial). I want to implement two independent Ethernet
interfaces: one an RJ45 capable of 10 and 100 Mbps, the other a classic
coaxial Ethernet interface with AUI and BNC ports. This way I can satisfy
everyone as far as Ethernet goes. There will be 3 serial ports: one for
LK201, one for DEC mice, and the remaining one a general-purpose EIA-232
port (DB25) that will be available for serial mice and for debug functions.
The hardware will basically be a generic PowerPC diskless workstation with
my StarMON ROM monitor (the one with the VAX console look and feel).
StarMON will boot over Ethernet (a non-volatile setting will indicate
which one) by broadcasting a BOOTP request and then TFTP'ing the boot
image indicated in the BOOTP reply. The X terminal software that will
be netbooted in this manner will be completely open source, but will be
packaged up to function like an OSless X terminal, i.e., no writable file
system, no user accounts, and no administration of or user exposure to the
local OS on the terminal. The Linux kernel will be booted with a RAM disk
read-only root filesystem which will also be fetched via TFTP at boot, and
that filesystem will contain a special init that will run the X server and
run the box like an OSless X terminal (XDMCP to a host specified in
configuration on the BOOTP/TFTP host).
Now there is only one thing remaining for which I seek advice from the great
collective wisdom here: what should I use for the video chip? Being the
recluse that I am, I know virtually nothing about modern video technology.
Out of modern, readily-available PCI video chips, what do you think would
be the most appropriate for a reasonable XFree86 server? As a ballpark
I'm looking for 24 bits per pixel colour (I don't want to be limited by
the colour map) and a resolution comparable to DEC's best offerings at
tne height of the VAXstation era. It would have to be PCI; whether I go
with the MPC8250 CPU or something else, it'll definitely have PCI but
not AGP.
I would appreciate any advice.
MS
On Apr 21 2005, 16:50, Jim Leonard wrote:
> Pete Turnbull wrote:
> > Um, your maths is off. Assuming 150 dpi is the minimum acceptable
for
> > well-printed text (and some DEC fiche is anything but), and a page
is
> > 8" wide, you need 1200 dots per page width. A page width on the
fiche
> > you describe is 6/16 inches, so you need 16/6 * 1200 dots per inch,
> > which is 3192 dpi.
>
> My apologies. Still, 4800 optical scanners are $600 or less, so I
still
> consider it possible.
I won't argue with that. Another thing that occurs to me is that one
could presumably build something like a fiche viewer over the scanner
glass; somthing to hold the fiche against a lens and project a
magnified image onto the scanner glass. I assume that, in essence, is
how Al's big fiche scanner works.
--
Pete Peter Turnbull
Network Manager
University of York
>Has anyone tried to plug an old Home computer into an Analog to Digital TV
>converter such as the Canopus ADVC-100, and then use a mondern computer
>with a Firewire port and video capture software as a monitor?
I don't know about that, but for a short while, I was running a C-128
into my PowerMac 6500's composite input and viewing the screen inside the
PowerMac. I can't speak for how well this would work long term, as I only
did it long enough to test the C-128 (only a few hours over the course of
about a week).
I got the idea, I thought from this list a number of years ago.
-chris
<http://www.mythtech.net>
>From: ard at p850ug1.demon.co.uk
>
>One think to be wary about. There is a capacitor across the filament
>string, after the capacitor. If the filament string is open-circuit for
>any reason, then that capacitor will charge to about 90V. It normally
>withstands that (although it's not rated to do so), but if you then
>replair the filament strign, there's enough energy in that capacitor to
>burn out one of the filaments. I always make sure that capacitor is
>discharged before fiddling with the valves.
Hi
Also a problem in the Zenith TO's.
>
>-tony
>
>From: "Bob Shannon" <bshannon at tiac.net>
>
>I've not been into R/C stuff, but I am into 'submini' tubes.
>
>I recently built a 5-tube regenerative receiver for the 49 meter band using
>5678's for the 2 stage tuned RF amp, detector, and first audio amp. A 5676
>serves as the final audio driver.
>
>Performance is awesome, and it runs on batteries. Warm-up time is at most
>3 seconds, nearly instant-on operation.
---snip---
Hi
The direct heated cathodes turned on fast enough that
one didn't have a noticeable delay. It wasn't until the
indirect heated cathodes that things changed. That was
because it was too hard to build an AC radio with the
directed heated tubes. There was both a hum problem
and it was more difficult to get each tube biased correctly.
Once they had selenium rectifiers, direct heated became
practical for low power applications ( like the Zenith TO's ).
They still had to do some tricks to get the biasing
working right for each tube. Some clever engineering.
Dwight
>Subject: LCD monitors (was Re: tube technology and EMP)
> From: "Eric Smith" <eric at brouhaha.com>
> Date: Fri, 22 Apr 2005 14:20:30 -0700 (PDT)
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>> A lot of users have noted that getting an LCD with 100% good pixels
>> is either tough or expensive.
>
>If you buy a name brand LCD, it's likely to cost a bit more and have
>fewer (or no) bad pixels.
>
Funny, went into the local ****usa and looked at several LCD monitors
and with care I spotted every one had at least one noticeable pixel bad.
The real problem was where I was they'd bring in some cheapo LCD and
I'd have to "deal with it" being the IT person as it was "broken".
Inshort I'd ahve to contact the vendor and try and get a good one and
usually the vendor would refuse as it met the 99.9995 good. Small
companies are that way.
>The normal failure mode for an LCD monitor is for one of the fluorescent
>tubes of the backlight to fail. These can be very expensive to replace
>as they are usually not common tubes.
That's my main worry.
Allison
>
>Subject: Re: tube technology and EMP
> From: William Donzelli <aw288 at osfn.org>
> Date: Fri, 22 Apr 2005 12:27:36 -0400 (EDT)
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>> Do LCD screens still blow pixels after a couple of years? That'd be my
>> only reservation compared to a traditional CRT.
>
>I'd rather blow a pixel than a whole gun...
>
>I actually still like a tube in front of me, but damn, these
>new(ish) flatscreens are nice.
>
>William Donzelli
>aw288 at osfn.org
My .02 is sure LCDs are nice, small and expensive but, they even come with a guarentee
that 99.99% of the pixels are good. The rest are well, bad.
A lot of users have noted that getting an LCD with 100% good pixels
is either tough or expensive.
Then again I have Monitors with the still common tube and when they
die it's 15$ here in MA to get rid of one with a bad gun or a
impossible to replace HV transformer. As a result I try to NOT
collect anything with a CRT onless it's fairly unique.
Allison
