Driver to drive?

Terry Given · Nov 4, 2004

Kevin Aylward wrote:

Rich Grise wrote:

On Wed, 03 Nov 2004 12:56:43 +0000, Kevin Aylward wrote:
[about FET current sources]

Vt\Vp can vary several hundred percent so this one off batch means
nothing. You can expect huge variations. Your "design" is an accident
waiting to happen.

So, in other words, are you saying, as was I, that coming off the
line, even with care in the production process, there is still so much
variation in the cutoff current

V Pinch off/V Threshold and Idss

that makes it such that you'd have
to individually test each unit? (which, of course, jacks the price
up a bunch)

Yes. Unless, of course your design can stand say, at least a +100%/-50%
variation in current.

Kevin Aylward

Which it probably cant, not if you wanted a "constant" current source
(sink) in the first place. Although I suppose if I tried hard enough I
could think of an application where the stability was important but not
the magnitude, just not off the top of my head.

How stable over temperature Kevin?

Cheers
Terry

Terry Given · Nov 4, 2004

Robert Baer wrote:

john jardine wrote:

"Andrew Holme" <andrew@nospam.com> wrote in message
news:cm2g7i$9j2$1$8302bc10@news.demon.co.uk...

Pooh Bear wrote:

How are you planning to get any realistic coupling ?

Disk read/write head fly mere microns above the platter surface. And
has been noted, provide uV of output.

Robert Baer wrote:

What may be bothersome, is the nasty question: what about
controlling the flying head height, and all of those *huge* (in
comparison) dust particles????????????
In short, haven't you scratched the sh*t out of the platter surface,
making it useless?

Yes, the head gap would have to be large enough to tolerate dust and small
enough to give good coupling. I don't know if this is possible. I was
planning to mount the head over the surface with a piece of paper between
them which I would later pull out. That is about the extent of my

precision

mechanical engineering capabilities.

The magnetic disk in this old computer was not air tight -
http://www.wps.com/projects/LGP-21/Documentation/Photos/index.html

I don't know how it worked. Maybe they had soft pads between the heads

and

the disk. I wonder how the disk coating differs from modern disks.

I'd be inclined just to to laquer the disc surface and spray with a dry film
lubricant.
Considering the surprisingly long lifetimes of both music cassette tapes and
the audio cassette heads, with that abrasive metal oxide tape, constantly
grinding into them, a audio head just lightly sitting on the prepared disc
surface seems little problem.
Audio cassette heads record and read at very low inches per second tape
speeds (signal sat on top of a H.F. bias oscillation and recovered levels at
'parts' of a mV ). Voltage out is proportional to how fast the magnetic
material is moving past the head, so some loss due to a small head gap could
be balanced by the faster platten speed. (even more so around the periphery

regards
john

Actually, audio tape is made with "lubricating" binders (makes surface
slick like teflon) and is far less "abrasive" than the finest paper
(which can be used as an ultra-fine "sandpaper").
It takes years of use for audio tape to wear into an audio head..

As usual, the mechanics behind something as common-place as a cassette
tape is a lot more complex than it might at first appear. I often think
I chose the easy option, becoming an electronics engineer.

Cheers
Terry

Reg Edwards · Nov 4, 2004

For design of simple filters and frequency response, download simple
programs -

LPF_HPF

and

BANDPASS1

from website below.
----
............................................................
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
............................................................

Paul Burke · Nov 4, 2004

nick wrote:

becase i have a 8 variables logic circuit ,i want to find a software to solve it
any kind of freeware can do that?

Lots, Lattice do one, Xilinx another, express the 8 inputs as logic
equations, run the HDL compiler, read the output. Or get OpalJr, or one
of half-a-dozen PLD compilers I've used, most of which are long forgotten.

But if it's a school exercise, use the freeware you already have- your
brain. An 8 input map is cumbersome, but not impossible, and you'll
soon realise why most people use HDLs these days.

Paul Burke

Fred Bloggs · Nov 4, 2004

Jim Thompson wrote:

On Thu, 04 Nov 2004 08:05:29 GMT, john_c@tpg.com.au (John Crighton)
wrote:

[snip]

You are confusing the term "union" with employee.
Employees may go on strike whether they are union members or not.

[snip]

Around here, in Arizona, striking by non-union types will simply get
you fired... pretty much the same rules as allowed Reagan to fire the
flight controllers.

...Jim Thompson

Those are called Air Traffic Controllers and not "flight controllers"-
and oh yeah- the FAA is quite the paradigm of efficiency. It is the most
backward and unproductive sewer in government, the technology is 20 year
behind the curve, and it was the *massive* corruption, incompetence, and
negligence of the FAA management of airport security that brought us
9/11. What more can one ask?

Keith Williams · Nov 4, 2004

In article <cmbn3l038j@drn.newsguy.com>, whill_a@t_rowland-dotties-
harvard-dot.s-edu says...

Terry Given wrote...

ps yay the Red Sox!

Hear! Hear! (Except for Kurt Shilling of course.)

At least Curt got it right (BTW, the man's name is Curt Shilling).

--
Keith

Jim Thompson · Nov 4, 2004

On Thu, 4 Nov 2004 10:03:17 -0500, Keith Williams <krw@att.bizzzz>
wrote:

In article <cmbn3l038j@drn.newsguy.com>, whill_a@t_rowland-dotties-
harvard-dot.s-edu says...
Terry Given wrote...

ps yay the Red Sox!

Hear! Hear! (Except for Kurt Shilling of course.)

At least Curt got it right (BTW, the man's name is Curt Shilling).

Come ON guys! The correct spelling is "Kurt Schilling", though
surfing shows Bostonians can't seem to spell ;-)

See http://www.freerepublic.com/focus/f-news/1262606/posts

for why Win Hill can't cope, but Schilling gets the last laugh as Win
has to pay up his $2K bet... must be why he's so quiet today ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Nov 4, 2004

On Thu, 04 Nov 2004 08:29:53 -0700, Jim Thompson
<thegreatone@example.com> wrote:

On Thu, 4 Nov 2004 10:03:17 -0500, Keith Williams <krw@att.bizzzz
wrote:

In article <cmbn3l038j@drn.newsguy.com>, whill_a@t_rowland-dotties-
harvard-dot.s-edu says...
Terry Given wrote...

ps yay the Red Sox!

Hear! Hear! (Except for Kurt Shilling of course.)

At least Curt got it right (BTW, the man's name is Curt Shilling).

Come ON guys! The correct spelling is "Kurt Schilling", though
surfing shows Bostonians can't seem to spell ;-)

See http://www.freerepublic.com/focus/f-news/1262606/posts

for why Win Hill can't cope, but Schilling gets the last laugh as Win
has to pay up his $2K bet... must be why he's so quiet today ;-)

...Jim Thompson

480)460-2350 | |
| E-mail Address at Website Fax

Keith Williams · Nov 4, 2004

In article <5jjko05t542iupoo9m2ihounv139q7uo5o@4ax.com>,
thegreatone@example.com says...

On Thu, 04 Nov 2004 08:29:53 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Thu, 4 Nov 2004 10:03:17 -0500, Keith Williams <krw@att.bizzzz
wrote:

In article <cmbn3l038j@drn.newsguy.com>, whill_a@t_rowland-dotties-
harvard-dot.s-edu says...
Terry Given wrote...

ps yay the Red Sox!

Hear! Hear! (Except for Kurt Shilling of course.)

At least Curt got it right (BTW, the man's name is Curt Shilling).

Come ON guys! The correct spelling is "Kurt Schilling", though
surfing shows Bostonians can't seem to spell ;-)

See http://www.freerepublic.com/focus/f-news/1262606/posts

for why Win Hill can't cope, but Schilling gets the last laugh as Win
has to pay up his $2K bet... must be why he's so quiet today ;-)

...Jim Thompson

CORRECTION:

It's a mix... seems even the Phoenix newspapers botch it up.

Sure, but I usually defer to the person when there is a question about
his name. ;-)

From baseball records....

Curt Schilling
Curtis Montague Schilling

The Free Republic article you linked above has an image of his Baseball
card with "Curt Shilling" written across it.

A funny (about half way down the page, under the caption; "Matt Damon
Wants You to Get Out and Vote"): http://www.bostondirtdogs.com/

--
Keith

Jim Thompson · Nov 4, 2004

On Thu, 4 Nov 2004 11:08:43 -0500, Keith Williams <krw@att.bizzzz>
wrote:

In article <5jjko05t542iupoo9m2ihounv139q7uo5o@4ax.com>,
thegreatone@example.com says...
On Thu, 04 Nov 2004 08:29:53 -0700, Jim Thompson
thegreatone@example.com> wrote:

On Thu, 4 Nov 2004 10:03:17 -0500, Keith Williams <krw@att.bizzzz
wrote:

In article <cmbn3l038j@drn.newsguy.com>, whill_a@t_rowland-dotties-
harvard-dot.s-edu says...
Terry Given wrote...

ps yay the Red Sox!

Hear! Hear! (Except for Kurt Shilling of course.)

At least Curt got it right (BTW, the man's name is Curt Shilling).

Come ON guys! The correct spelling is "Kurt Schilling", though
surfing shows Bostonians can't seem to spell ;-)

See http://www.freerepublic.com/focus/f-news/1262606/posts

for why Win Hill can't cope, but Schilling gets the last laugh as Win
has to pay up his $2K bet... must be why he's so quiet today ;-)

...Jim Thompson

CORRECTION:

It's a mix... seems even the Phoenix newspapers botch it up.

Sure, but I usually defer to the person when there is a question about
his name. ;-)

From baseball records....

Curt Schilling
Curtis Montague Schilling

The Free Republic article you linked above has an image of his Baseball
card with "Curt Shilling" written across it.

A funny (about half way down the page, under the caption; "Matt Damon
Wants You to Get Out and Vote"): http://www.bostondirtdogs.com/

480)460-2350 | |
| E-mail Address at Website Fax

Rene Tschaggelar · Nov 4, 2004

sudheervemana wrote:

HI all,

In my application board there was an converter called
CONV485-DB9 which converts rs232 data in to rs485 which is an DB9
connector at both ends.Can anyone help me to checkout the converter
whether it is working properly or not.

I had given the RS232 female end to my serial COM port and the
other end of the RS485 male connector was given to my application
board,which contains an RS485 Half duplex tranceiver.I have utilized
only 3 pins namely 2,3,5 of the RS485 connector.These signals were
given to my transceivers differntial voltage pins A and B.Does these
signals are sufficient for transmitting the data.

When i am trying to detect the baudrate of my Dsp
controller,it was getting failed.My Host PC will send some data and
receives the data from the controller.

At the time of testing my RS232 port through accesing some
software,i am able to see some data that was transmitting through the
2(tx) and 3(rx) pins of rs232 port,whereas when i am trying to see the
same data at the other end of my converter which is at the RS485 port
side,i am not able to see any voltage,Does my converter fails or else
is there anything wrong with the half duplex.Atleast i should see some
data at the rs485 port side pins.I am having two such converters,both
of them were giving the same problem.

The problem with the RS232 <-> RS485 conversion is that the direction
of the driver has to be changed. Usually on a message level.
This is not really doable with a PC when the other side is much faster.
The PC tends to use the DTR pin of the uart for the direction.
The problem ist that the direction has to be changed at the end of the
message. The end of the message is not the last Tx_Empty interrupt,
but one byte later. The Tx_Empty interrupt comes when the buffer is
empty. At that time the last byte is being shifted out. So one needs
a timer to wait for the last bit having been shifted out.
Since Bill G. mucked up the interrupt structure of the iAPX86 family,
you won't get this timer interrupt for certain at this time, but perhaps
somewhat later.
What happens when the PC switched the direction too late ?
Well, the other side may already have begun sending its stuff and
the PC misses part of it.

To debug, you need a pair of resistors in the lines that allow you
to figure the direction of the current.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Ken Smith · Nov 4, 2004

In article <q9rio0tmtoum5nhait6c4r2324oabaq3tn@4ax.com>,
John Larkin <jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote:
[...]

How so? I'd suspect a polycarb or something decent would have a very
low df in the sub-Hz range.

Have you tried desinging in polycarbs lately? If you did, how did you
survive the beating you got from purchasing?

Also I've never seen them in surface mount. I haven't looked very hard,
but I think I would remember.

Numbers like 1 uF and 10 megohms seem
perfectly nice to me, with fet opamps.

That would make for quite a bit of noise. I don't know if the OP can
stand the noise in his design.
--
--
kensmith@rahul.net forging knowledge

John Fields · Nov 4, 2004

On Thu, 04 Nov 2004 08:05:29 GMT, john_c@tpg.com.au (John Crighton)
wrote:

Sorry but you are wrong.
You are confusing the term "union" with employee.
Employees may go on strike whether they are union members or not.
A union does not go on strike.
Employees may go on strike if they wish.
Are we speaking the same language now?

---
Usually, when a shop goes union the entire shop goes union (becomes
what's known as a "closed shop") and the individual employees agree to
allow the union to negotiate any and all matters which may come up
between them (the individual employee) and management. This includes
working conditions, increases in compensation, medical benefits,
punitive actions the company may take against employees (for
infractions of union-allowed rules), severance benefits, everything.

Consequently, after the union comes into power (and it's _just_ that)
no employee may discuss anything with management without union
representation being present.

Without the permission of the union, no single member or group of
members can go on strike, and when the _union_ decides to go on strike
it does. There _is_ the formality of the ratification of the action
by the members of the union, but that's usually a fait accompli since
disagreement with union _management_ (LOL!) is severely frowned upon.

Bottom line is, the union wants to wrest all control from the company
and wants to make sure those dues keep rolling in.

--
John Fields

Ken Smith · Nov 4, 2004

In article <10oiu8liv0t6e39@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
[...]

Sampling at 150Hz will make the anti-aliasing easy, and even an 8051

I did something a lot like this. In my case it was about 180Hz that I
needed to measure the amplitude of. The 8051 samples at about 5KHz with
plenty of time to get around the loop.

If you like 8051s and want speed, look at the Cygnal products. 100MIPS in
an 8051 is a fun idea.

--
--
kensmith@rahul.net forging knowledge

John Larkin · Nov 4, 2004

On 4 Nov 2004 03:57:33 -0800, bill.sloman@ieee.org (Bill Sloman)
wrote:

In so far as the timing of the invasion of Irak was determined by
Dubbya's bid for a second term, one can wonder about the landslide -
as incumbent candidates go, he's done pretty poorly. The war in Irak
has allowed him to present himself as a resolute war leader, and
distracted the voters from the vile state of the economy.

But it's not vile. GNP growth is nicely positive, unemployment is just
over 5% (compare that to Europe!), and we've absorbed and employed
tens of millions of immigrants in the last few years. Lots of jobs are
available to anyone with even modest skills.

John

John Fields · Nov 4, 2004

On Thu, 04 Nov 2004 11:09:30 -0700, Mark Fergerson <nunya@biz.ness>
wrote:

John Fields wrote:

Bottom line is, the union wants to wrest all control from the company
and wants to make sure those dues keep rolling in.

Close. It wants to wrest all control from the _employees_
and charge them for the privelige of making their decisions
for them.

---
That works for me...

--
John Fields

Joel Kolstad · Nov 4, 2004

"Paul Burke" <paul@scazon.com> wrote in message
news:2uukkhF2d5084U1@uni-berlin.de...

But if it's a school exercise, use the freeware you already have- your
brain. An 8 input map is cumbersome, but not impossible, and you'll soon
realise why most people use HDLs these days.

I wasn't aware that Karnaugh maps could be (systematically) used for more
than 5 variables? Can they be? Back when I was in school we used the
'table method' (I've forgotten the real name) beyond 4.

And 4 is enough to convince people of the value of HDLs, I think!

Joerg · Nov 4, 2004

Hello Radiohead,

In the old days it used to be done with a stash of Potter&Brumfield
relays plus a can of contact spray ;-)

No joke, this scheme is pretty resistant against all kinds of nasty
surprises like overvoltage, wrong connection, shorts etc. Also, you can
'set a bit' by removing the cover and poking with a plastic stick.

Regards, Joerg

http://www.analogconsultants.com

Fred Bloggs · Oct 30, 2004

Tom Seim wrote:

All of the above are false, of course. That's a fact. If you believe any of
the above, you've been watching Fox News too much. That's a problem with Bush
supporters. When they're confronted with facts that contradict their belief
system, they'll ignore the fact and switch the channel back to Fox.

Enough of the El Ka-ka stuff. Five more days, gentlemen. Who you gonna
believe, the administration or your lyin'eyes? You're all engineers,
designers, technicians. You're the ones who are supposed to believe in pure
d***ed facts, and leave the spin and unsupported "argument by assertion" to the
finance MBAs and marketing PHBs in the front office. Let's look at the facts,
just like we do to earn a living.

Chris

OK, you convinced me. I'm voting for BUSH!

That's because you are NOT an engineer- you're exactly the kind of
parasitic peripheral riffraff Chris was talking about- you were not
addressed here.

Ken Smith · Nov 4, 2004

In article <v3jid.259388$35.12111996@news4.tin.it>, Ban <bansuri@web.de> wrote:

Tim Wescott wrote:
[...]
Well I was referring to the before mentioned 150Hz sample rate. If you
oversample a lot more(with 40k sample 0.05Hz is almost 1/1mio!) the analog
filter gets relaxed specs, but the precision of the IIR coefficients require
more and more effort (float, double precision) so there will be an optimum
depending on your MCU/DSP.

Use fixed point. If you store everything as giant integers, there is less
trouble. The 8052 has 256 bytes so you can fit nearly 32 8 byte integers
in it.

--
--
kensmith@rahul.net forging knowledge

Driver to drive?

Terry Given

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Reg Edwards

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Jim Thompson

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