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Op amps problem Gain Calculation

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Steve Modica
Guest

Mon Jul 11, 2005 4:03 pm   



Tony 'Nicoya' Mantler wrote:
Quote:
In article <bwpatter-4AF545.12075809072003_at_news.bellatlantic.net>,
Blake Patterson <bwpatter_at_bellatlantic.net> wrote:

: I had to take apart my SGI 1600SW flatscreen monitor to clean it out
: with distilled water becuase it had been rained on from a leaking duct
: with mineralized water. I had to cut through some metal shielding tape
: that was used on some internal metal parts to get the screen out. I
: want to replace this with some new tape, but Radio Shack does not seem
: to carry this thin tape. It's like a strip of adhesive aluminum foil.
:
: What is this stuff actually called and where can I order some online?

Google to the rescue: http://froogle.google.com/froogle?q=aluminum+foil+tape

You should be able to get aluminum foil tape at any hardware store or home
center, it's usually used for sealing ductwork (as opposed to using ductape,
which is most definatley not good for sealing ductwork - the adhesive on
aluminum foil tape should last much longer).


Cheers - Tony 'Nicoya' Mantler :)


yeah.. I discovered this myself. traditional duct tape doesn't stick to
ducts very well. The foil stuff sticks extremely well. (not sure if
the adhesive is conductive tho. If it's not, you'll have to be careful
to make sure your shielding is grounded somehow.

Steve

--
Steve Modica
"Give a man a fish, and he will eat for a day, hit him with a fish and
he leaves you alone" - me

Tony 'Nicoya' Mantler
Guest

Mon Jul 11, 2005 4:03 pm   



In article <behmn8$4sgcp$1_at_fido.engr.sgi.com>, Steve Modica <modica_at_sgi.com>
wrote:

: not sure if
: the adhesive is conductive tho. If it's not, you'll have to be careful
: to make sure your shielding is grounded somehow.

I would think that even if the adhesive isn't conductive, the capacitive
coupling to the grounded parts of the shielding that the tape would partially
cover should be enough to handle most EMI concerns.


Cheers - Tony 'Nicoya' Mantler :)

--
Tony "Nicoya" Mantler - Renaissance Nerd Extraordinaire - nicoya_at_apia.dhs.org
Winnipeg, Manitoba, Canada -- http://nicoya.feline.pp.se/

Gary Heston
Guest

Mon Jul 11, 2005 4:03 pm   



In article <nicoya-829137.11343209072003_at_news.pp.shawcable.net>,
Tony 'Nicoya' Mantler <nicoya_at_apia.dhs.org> wrote:
Quote:
In article <bwpatter-4AF545.12075809072003_at_news.bellatlantic.net>,
Blake Patterson <bwpatter_at_bellatlantic.net> wrote:

: I had to take apart my SGI 1600SW flatscreen monitor to clean it out
: with distilled water becuase it had been rained on from a leaking duct
: with mineralized water. I had to cut through some metal shielding tape
: that was used on some internal metal parts to get the screen out. I
: want to replace this with some new tape, but Radio Shack does not seem
: to carry this thin tape. It's like a strip of adhesive aluminum foil.

: What is this stuff actually called and where can I order some online?

Google to the rescue: http://froogle.google.com/froogle?q=aluminum+foil+tape

You should be able to get aluminum foil tape at any hardware store or home
center, [ ... ]

Or, you can go to most auto parts places and get exhaust pipe/muffler
repair tape, in nice shiny chrome.


Gary

--
Gary Heston gheston_at_hiwaay.net
PHB: "That's the sort of leadership that will turn this company around."
Wally: "Were we doing well?"
Dilbert, 5/23/3

Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



Tony 'Nicoya' Mantler <nicoya_at_apia.dhs.org> wrote in message
news:nicoya-67D955.15253109072003_at_shawnews.wp.shawcable.net...
Quote:

I would think that even if the adhesive isn't conductive, the capacitive
coupling to the grounded parts of the shielding that the tape would
partially cover should be enough to handle most EMI concerns.

I think the *opposite* is true because you would essentially form a huge
metal-oxide-metal (MOM) transistor, i.e.:

metal tape layer
---------------------------------------------
capacitive coupling through adheisive layer
---------------------------------------------
metal shielding layer

The RF energy radiated from sweeping the electon beam would be pumped
through the nonlinearity created by the tape "transistor" and re-radiated on
multiple frequencies. The effect is known as passive intermodulation or
PIM. Using non-conductive tape for EMI shielding is worse than leaving the
hole.

And of course there are also the safety issues created (read: huge electric
shock hazard) from using a high voltage electric field to capacitively
charge a piece of ungrounded metal...

- Mike

Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



Its called "conductive aluminum tape" (seriously). You can probably pick
some up at a local hardware store next to the duct tape.

I think 3M offers it for sale as an OEM, but I doubt you're interested in a
large quantity--I expect that you only need a few inches to repair the
shield. However, if you can't find what you want at a local hardware store
you can probably get free samples from 3M.

The word *conductive* is critical -- using non-conductive tape would create
a really large metal-oxide-metal transistor. Moreover, it could be unsafe
since the ungrounded metal tape is capacitively coupled to a high voltage
source.

- Mike

Khalid Schofield
Guest

Mon Jul 11, 2005 4:03 pm   



yeh I've not heard of MOM transistors either. But as for metal tape I'd
use Aluminium tape. RS sell the stuff by the role. All good hardware
stores sell Aluminium tape too. I use it to cover pipe thermal insulation
on our cooling systems.

hope this is of some help

regards

-----------------------
Khalid Schofield
(686b 6c61 6469 7320 6863 666f 6569 646c 000a)
Unix System Administrator and EM Technician
Department of Materials
University of Oxford
Parks Road
Oxford OX1 3PH
UK

Tel: +44-1865-273785
Fax: +44-1865-273789

khalid.schofield_at_materials.ox.ac.uk

(686b 6c61 6469 732e 6863 666f 6569 646c
6d40 7461 7265 6169 736c 6f2e 2e78 6361
752e 0a6b)

http://www-em.materials.ox.ac.uk/people/schofield/index.html

On 10 Jul 2003, Arno Wagner wrote:

Quote:
In comp.sys.ibm.pc.hardware.misc Michael Pender <mpender_at_hotmail.com> wrote:
Tony 'Nicoya' Mantler <nicoya_at_apia.dhs.org> wrote in message
news:nicoya-67D955.15253109072003_at_shawnews.wp.shawcable.net...

I would think that even if the adhesive isn't conductive, the capacitive
coupling to the grounded parts of the shielding that the tape would
partially cover should be enough to handle most EMI concerns.

I think the *opposite* is true because you would essentially form a huge
metal-oxide-metal (MOM) transistor, i.e.:

metal tape layer
---------------------------------------------
capacitive coupling through adheisive layer
---------------------------------------------
metal shielding layer

This has no transistor effect at all. If it had, every capacitor
would be a transistor.

I also have never heard of MOM stransistrs, only MOS.

The key to MOS transistors is a semi-conductor that has movable
electrons and can be made more or less conducting by applying an
external electric field.

Should I be mistaken, please provide a reference for "MOM Transistors"

Regards,
Arno

--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus




Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



Achim Hensel <achim.hensel_at_ruhr-uni-bochum.de> wrote in message
news:20030710144959.6dc33636.achim.hensel_at_ruhr-uni-bochum.de...
Quote:
Hai, Folks..

I had to take apart my SGI 1600SW flatscreen monitor to clean it out

This is a flatscreen; no huge voltages, no electrobeams.

You're right -- my bad. :-)

Quote:
I think the *opposite* is true because you would essentially form a
huge metal-oxide-metal (MOM) transistor, i.e.:

This will work as a transistor, This is just a capacity. The
transistor would need an other/third contact to modify the electric
properties of the intermediate layer (I also do doubt if a
metal-insulator-metal structure with that insulator matter and
thickness can fuction as a transistor).

You can call it a transistor, or a diode, or a non-linear junction--the
effect is the same either way.

Quote:
Indeed a non-linear device (non-linear reaction to voltage) can
transduce a signal to different frequencies. But a capacity is, in this
regard, just a linear device. It might react different to various
frequencies, but it's reaction is proportional to the voltage (and
signal), so no other frequencies can be produced.

The metals will oxidize over time (days or weeks, not months) creating an
oxide layer between the metal surfaces. The device formed is *not* a mere
capacitor.

Quote:
Tape with a conductive layer should seal the flatscreen to electronic
immissions and emissions. I really doubt, if high voltages are produced,
so that should be no problem.

Since its just a flatscreen (and I'm expressly presuming an LCD or similar
this time, not a CRT with a relatively flat front) my concerns about the
electron beam sweep and high voltage were misplaced.

Quote:
If you really need connecting the metal tape layer to the metal base use
[well, I don't know the english word for it; in german it's
"Leitsilber". It's a conducting liquid which will dry and then form an
electric connection; maybe it's called "conduction silver paint" or
"Colloidal silver"].

Do you know where I can get some? I've had a difficult time locating any
sources for it.

Thanks,

Mike

Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



Arno Wagner <me_at_privacy.net> wrote in message
news:bejt38$5svc1$2_at_ID-2964.news.dfncis.de...
Quote:

This has no transistor effect at all. If it had, every capacitor
would be a transistor.

Perhaps every *unsealed* capacitor would act like a resistor.

Quote:
I also have never heard of MOM stransistrs, only MOS.

Okay, then think of as a a really large diode, where the oxidized metal
surfaces form the semiconductor material.

Quote:
The key to MOS transistors is a semi-conductor that has movable
electrons and can be made more or less conducting by applying an
external electric field.

Since this is apparently an LCD monitor (I thought it was like a Sony
Triniton flat-screen, not an LCD) the voltages are not likely to be high
enough for this to be an issue.

Quote:
Should I be mistaken, please provide a reference for "MOM Transistors"

Regards,
Arno

The references I used are proprietary.

If you are seriously interested then I recommend:
- search Google for references on "passive intermodulation" or "PIM"
- pick up a copy of the conference report by the European Space Agency:

Multipactor, RF and DC Corona and Passive Intermodulation in Space RF
Hardware", 4-6 September 2000, ESTEC, Noordwijk, The Netherlands.

- Mike

Arno Wagner
Guest

Mon Jul 11, 2005 4:03 pm   



In comp.sys.ibm.pc.hardware.misc Michael Pender <mpender_at_hotmail.com> wrote:
Quote:
Arno Wagner <me_at_privacy.net> wrote in message
news:bejt38$5svc1$2_at_ID-2964.news.dfncis.de...

This has no transistor effect at all. If it had, every capacitor
would be a transistor.
Perhaps every *unsealed* capacitor would act like a resistor.

Resistor for RF yes, transistor no. A transistor is an active
component, while a resitor or a capatitor is not.

Quote:
I also have never heard of MOM stransistrs, only MOS.
Okay, then think of as a a really large diode, where the oxidized metal
surfaces form the semiconductor material.

Since when does oxydized metal have semiconductor-properties?
In fact in a MOS-FET, the metal oxyde froms the insulator, just like
the PN-junktion in a JFET.

Quote:
The key to MOS transistors is a semi-conductor that has movable
electrons and can be made more or less conducting by applying an
external electric field.

[...]

Quote:
The references I used are proprietary.

If you are seriously interested then I recommend:
- search Google for references on "passive intermodulation" or "PIM"
- pick up a copy of the conference report by the European Space Agency:
Multipactor, RF and DC Corona and Passive Intermodulation in Space RF
Hardware", 4-6 September 2000, ESTEC, Noordwijk, The Netherlands.

Aha, now I know what you are talking about! (Roughly, as this RF
stuff is in part black magic in my eyes.) This is not about an
active element, but rather a passive mixer/modulator/resonator-effect.
Yes that could certainly happen with isolated strips of conducting
material.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus

Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



Michael Pender <mpender_at_hotmail.com> wrote in message
news:PUiPa.65379$JY1.11743_at_nwrddc01.gnilink.net...
Quote:
Arno Wagner <me_at_privacy.net> wrote in message
news:bejt38$5svc1$2_at_ID-2964.news.dfncis.de...

This has no transistor effect at all. If it had, every capacitor
would be a transistor.

Perhaps every *unsealed* capacitor would act like a resistor.

I can't believe that I typed 'resistor'!!

I'm using Outlook Express as a newsgroup reader. Can anyone tell me how to
disable the spell-checker in Outlook Express so it stops offering to 'fix'
my 'mistakes' for me?

Thanks in advance,

- Mike

Bill Garber
Guest

Mon Jul 11, 2005 4:03 pm   



"Michael Pender" <mpender_at_hotmail.com> wrote in message
news:nCmPa.76164$n%5.16827_at_nwrddc02.gnilink.net...
Quote:
Michael Pender <mpender_at_hotmail.com> wrote in message
news:I7mPa.65478$JY1.23957_at_nwrddc01.gnilink.net...
...snip...
I'm using Outlook Express as a newsgroup reader. Can anyone tell me how
to
disable the spell-checker in Outlook Express so it stops offering to
'fix'
my 'mistakes' for me?

I figured out how to change Outlook Express so that the spell checking is
now optional. Hopefully my posts will make a little more sense now. :-)

Can anyone recommend a better newreader than Outlook Express? Are there
any
news readers available for the Apple II?

Since this may be drifting too far off-topic, please respond by e-mail.

This whole damned thread is OFF-TOPIC!

Bill @ GarberStreet Enterprises }Wink
Web Site - http://garberstreet.netfirms.com
Email - willy46pa_at_comcast.net



---
This email ain't infected, dude!

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.495 / Virus Database: 294 - Release Date: 6/30/03

DarkMatter
Guest

Mon Jul 11, 2005 4:03 pm   



On Wed, 09 Jul 2003 16:07:58 GMT, Blake Patterson
<bwpatter_at_bellatlantic.net> Gave us:

Quote:
I had to take apart my SGI 1600SW flatscreen monitor to clean it out
with distilled water becuase it had been rained on from a leaking duct
with mineralized water. I had to cut through some metal shielding tape
that was used on some internal metal parts to get the screen out. I
want to replace this with some new tape, but Radio Shack does not seem
to carry this thin tape. It's like a strip of adhesive aluminum foil.

What is this stuff actually called and where can I order some online?

Thanks.


Digi-Key and Mouser both have "copper tape". Many uses, among which

are taping the edge of a Cathode Ray Tube. I know your isn't that.,
but that is what we use it for. Little 5" monitors.

I also saw some in a mag for electronic manufacturing supplies, like
tape. I'll find it on my desk at work, and list it for ya.

DarkMatter
Guest

Mon Jul 11, 2005 4:03 pm   



On Wed, 09 Jul 2003 13:25:44 -0500, Steve Modica <modica_at_sgi.com> Gave
us:

Quote:

yeah.. I discovered this myself. traditional duct tape doesn't stick to
ducts very well. The foil stuff sticks extremely well. (not sure if
the adhesive is conductive tho. If it's not, you'll have to be careful
to make sure your shielding is grounded somehow.


Very good. Adhesive type, and thickness are important factors. The
copper tape sold for this use is coated very thinly with what I'm sure
is NOT an insulative material. Well... reasonably sure.

DarkMatter
Guest

Mon Jul 11, 2005 4:03 pm   



On Thu, 10 Jul 2003 20:17:06 -0400, "Bill Garber"
<willy46pa_at_comcast.net> Gave us:
Quote:

"Michael Pender" <mpender_at_hotmail.com> wrote in message
Are there
any
news readers available for the Apple II?

To Michael: Try netscape 3.0?

Quote:

Since this may be drifting too far off-topic, please respond by e-mail.

This whole damned thread is OFF-TOPIC!


WHOOPIE DOO, YA WUSS. It isn't in alt.electronics.

Life just ain't that tragic. Jeez.

Michael Pender
Guest

Mon Jul 11, 2005 4:03 pm   



DarkMatter <DarkMatter_at_thebarattheendoftheuniverse.org> wrote in message
news:m3asgvgl5ccr6723v0cl3m9nnnhj03nsu5_at_4ax.com...

Quote:
Are there any news readers available for the Apple II?

To Michael: Try netscape 3.0?

Are you *sure* that Netscape makes a news reader for the Apple II?

I checked Netscape's web site and don't see any mention of a news reader for
the Apple II -- you do realize that the Apple II is *not* a Mac, right?

Please point me to where I can find a copy, if it exists.

- Mike

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