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Maintaining a Vbe Multiplier's bias value

J

Jon Kirwan

Jan 1, 1970
0
On Fri, 12 Feb 2010 19:28:51 -0700, Jim Thompson
[snip]
Learn Laplace short-hand, it'll be invaluable!

...Jim Thompson

I'm gradually getting more comfortable with Laplace, as I
continue to work more problems. It is an especially nifty
way to solve some differential equations, which is what it
was designed to do, I think.

Jon

Actually, shorthand Laplace was created by none other than Oliver
Heaviside: http://en.wikipedia.org/wiki/Oliver_Heaviside

...Jim Thompson

Now that's an impressive man. Thanks! I'll dig in!

Jon
 
J

JosephKK

Jan 1, 1970
0
It's a current mirror, based on hFE instead of Vbe (yuck!). When Q1 or Q4
saturates, bias current (or op-amp current) is diverted to the output
transistors, driving the load.

Tim

No, i don't think it is even that good.
 
J

JosephKK

Jan 1, 1970
0
Well, I am wanting, eventually, to build something I need.
Something I cannot buy in the market because the need is
unique.

This divides into two parts. Design and build. Since the
item is unique, I can't just go out and buy it. And getting
the features I need cannot just be "hacked" into existing
designs without at least knowing _some_ stuff, first. I
might as well turn the "design" part into a fair learning
experience, as a separate project of its own. Get past that
and when it comes time to build what I want I'll be able to
build on what I learned and add what I need and then do a
modest hobbyist level whack at actually making what I want to
make.

If someone else were to do this for me (hire a designer),
they'd get all the fun of learning on the job and taking my
money with it. They get the money, they get to further their
own education, and I get a tool. One tool. Once. Next
time, I get to pay someone else to learn for me.

It almost feels like paying someone to go do your exercising
for you. No satisfaction and no weight loss. They get all
the _real_ benefits.

Part of the fun isn't the destination itself but it is what
you see and enjoy while getting there, too. You take a plane
when all you need is to "get there" quick, but you drive when
you want to enjoy stops along the way. I used to fly to
Burbank every week for a year and a half. Slept in a hotel
for 3 nights a week, worked day and night in between, flew
home. Barely saw anything but hotel room walls, cubical
walls, a few cement roads, pollution so thick you couldn't
see the Burbank hills from the Lockheed center, and not much
else. The destination was important, of course. Paid the
bills and I enjoyed the work, too. But there is a lot more
to see in the 1000 miles from here to there.

Anyway, I'm driving this time, not flying.

Besides, I'd rather _keep_ the money and _keep_ the education
for myself. That way it pays off, again and again.

Jon

Spot on. That is why i am rebuilding my tinkering kit.
 
J

Jon Kirwan

Jan 1, 1970
0
3. Hang a big cap across it.

Assume, just for a moment, that one wants to actually learn a
little about _designing_ the part that goes across those cap
terminals.

Jon
 
F

Fred Abse

Jan 1, 1970
0
Almost. It's more like: I'd like to get to Fresno Flats
(aka Oakhurst, near Yosemite) from Portland

Oakhurst is too touristy/resorty these days.

I usually stop at a little diner in Coarsegold, a few miles before, when
I drive into Yosemite that way.
 
F

Fred Abse

Jan 1, 1970
0
On Fri, 12 Feb 2010 19:28:51 -0700, Jim Thompson
[snip]

Learn Laplace short-hand, it'll be invaluable!

...Jim Thompson

I'm gradually getting more comfortable with Laplace, as I
continue to work more problems. It is an especially nifty
way to solve some differential equations, which is what it
was designed to do, I think.

Jon

Actually, shorthand Laplace was created by none other than Oliver
Heaviside: http://en.wikipedia.org/wiki/Oliver_Heaviside

...Jim Thompson

Now that's an impressive man. Thanks! I'll dig in!

He was self-taught, too.
 
F

Fred Abse

Jan 1, 1970
0
On Thu, 11 Feb 2010 11:50:23 -0700, Jim Thompson




Okay. That's gone, then.

I still get regular emails from JEDEC. They all seem to be about some
conference or seminar on lead-free.
 
F

Fred Abse

Jan 1, 1970
0
No hurry. Thanks, Bob Monsen

It's at:

http://www.infinitefactors.org/misc/asc.zip

It contains just two files, the EXE and a library symbol
file. Place both in some directory that is in the path. You
need to use DOS, sadly. I didn't set these up for Windows --
wanted to focus on the task, not get mired in Windows
sideshows.

If you run the program without a filename, it will say:
: asc version 1.2.1, (library C:\TOOLS\BIN\ASC.SYM found)
:
: This program converts LTSpice schematics into ASCII schematic output (or
: files.) If you specify no files at all, it accepts the LTSpice schematic
: from its standard input device. If you specify exactly one file, it dis-
: plays the ASCII schematic output to the standard output device. If you
: specify more than one file, it then generates .TXT files otherwise having
: the same name as the specified schematics.
:
: These options are supported:
: +h requests this help message, -h disables it.
: +r enables rectangle drawing, -r disables it (default is -r)
: +c enables clipboard copying, -c disables it (default is -c)
: +c<char> enables clipboard copying and prepends <char> to each line
:
: Usage: asc <options> <filename> [<filename>]...

There are some options, like the clipboard. But post
Win2000, that mechanism was broken and I haven't set up the
additional DLL I'd need to remedy it. (Something I may yet
take care of.) So under WinXP, for example, I just run it
into a file and use notepad to call it up. Something like:

ASC amplify.asc >amplify.txt
NOTEPAD amplify.txt

It gets the job done. Under Win98SE, I just use the +c
option and then paste the text, as desired, in Windows.

The library is semi-okay. There's some symbols I've probably
not yet added to it because I don't use the parts that much.
I won't mind extending it (it's not hard to do) if there is
anything you use and would like put in. I just use a text
editor and hack in the new ASCII and then save it. The
program automatically parses it every time it runs.

Jon

Runs fine under dosemu here. "ASC file.asc file.txt" produces an empty file,
"ASC file asc > file.txt" (output redirect) works.

Obviously the source won't compile for linux.
It needs someone that knows far more about C (yecch!) than I do to port it.

Any offers?
 
J

Jon Kirwan

Jan 1, 1970
0
Oakhurst is too touristy/resorty these days.

I usually stop at a little diner in Coarsegold, a few miles before, when
I drive into Yosemite that way.

:)

I last visited there in the 90's. The big deal there at
Oakhurst, at the time, was "The Imagination Network." I had
many mixed feelings during that visit.

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
On Fri, 12 Feb 2010 19:05:46 -0800, Jon Kirwan

On Fri, 12 Feb 2010 19:28:51 -0700, Jim Thompson

[snip]

Learn Laplace short-hand, it'll be invaluable!

...Jim Thompson

I'm gradually getting more comfortable with Laplace, as I
continue to work more problems. It is an especially nifty
way to solve some differential equations, which is what it
was designed to do, I think.

Jon

Actually, shorthand Laplace was created by none other than Oliver
Heaviside: http://en.wikipedia.org/wiki/Oliver_Heaviside

...Jim Thompson

Now that's an impressive man. Thanks! I'll dig in!

He was self-taught, too.

Well, then. Maybe there is hope for me, too? ;)

Jon
 
J

Jon Kirwan

Jan 1, 1970
0
Just Larkin, as typical, throwing sand in the air.

Simulate it, it's crap for other than low current applications... some
_really_ bizarre behavior.

...Jim Thompson

My instincts were alerted as soon as I saw it.

Jon
 
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