Op amps problem Gain Calculation

[DarkMatter]

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

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]

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

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]

On Thu, 10 Jul 2003 20:17:06 -0400, "Bill Garber"
<willy46pa@comcast.net> Gave us:

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

To Michael: Try netscape 3.0?

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]

DarkMatter <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:m3asgvgl5ccr6723v0cl3m9nnnhj03nsu5@4ax.com...

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

 

[happyhobit]

If you're talking about IrDA check out this site.

http://rcswww.urz.tu-dresden.de/~sb831436/irda/irda.htm

Jay

 

[DarkMatter]

On Fri, 11 Jul 2003 06:35:16 GMT, "Michael Pender"
<mpender@hotmail.com> Gave us:

DarkMatter <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
news:m3asgvgl5ccr6723v0cl3m9nnnhj03nsu5@4ax.com...

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.

You probably can't just hit netscape's site and get archived
releases. But yeah.. I guess it is very unlikely that platform is
carried.

 

[Walter Roberson]

In article <2dl0hvgpe403ahphm5rfqk6e5f76jndann@4ax.com>,
DarkMatter <TheBartenderBuyMeADrink> wrote:
:On Fri, 11 Jul 2003 06:35:16 GMT, "Michael Pender"
:<mpender@hotmail.com> Gave us:

:>DarkMatter <DarkMatter@thebarattheendoftheuniverse.org> wrote in message
:>news:m3asgvgl5ccr6723v0cl3m9nnnhj03nsu5@4ax.com...

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

: You probably can't just hit netscape's site and get archived
:releases. But yeah.. I guess it is very unlikely that platform is
:carried.

As a matter of fact, you can get archived releases from Netscape.
http://wp.netscape.com/download/archive.html

No sign of a release for an Apple II, though.

--
vi -- think of it as practice for the ROGUE Olympics!

 

[DarkMatter]

On 11 Jul 2003 09:12:12 -0700, aldous_b@yahoo.com (Aldous B) Gave us:

hello,
I would like to ask if there is a schematic diagram/design for an
infrared comm module that can be attached to the pc motherboard. I
would like to communicate with a mobile device (or some other device
with ir).

What kind of communication? Data input? user interface with the PC?
What?

Also, if it is an existing device, the comm system in it is likely
proprietary to that company's hardware. Mobile device? Laptops
already have IR links in them for PCs. The PC device is available.
Laptops use the radio links mostly these days though.

I found a couple of designs in the net- the design is very
simple, but when i checked for the availability of the IR
transceiver/receiver - i can't find it locally. I can't and probably
won't buy a single component from the net since the shipping alone
will be outrageously high. The design that I found has the tranceiver
and receiver on a single component. I've read that it has some chip of
some kind (i'm not really that sure).
The only available components are separated - they look like
LEDs. I would like to ask if there is an available schematic
diagram/design for an IR comm. device that uses these components. I'm
quite a begginner with electronics and I cannot design my own device.

If you are that much the beginner, this particular level of

sophistication may be to great a leap for you at this time.

Thank you very much for your help.

Why not secure wireless? You can get a remote microphone that has a
comm link for a PDA here:

www.avalonrf.com

 

[Arno Wagner]

In comp.sys.ibm.pc.hardware.misc DarkMatter <DarkMatter@thebarattheendoftheuniverse.org> wrote:

On Thu, 10 Jul 2003 20:17:06 -0400, "Bill Garber"
willy46pa@comcast.net> Gave us:

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

To Michael: Try netscape 3.0?

Good joke!

Seriously the Apple II has several orders of magnitude
to little RAM and CPU-power for a modern graphical browser.

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

 

[Zeducious Monk]

On 11 Jul 2003 09:12:12 -0700, aldous_b@yahoo.com (Aldous B) wrote:

hello,
I would like to ask if there is a schematic diagram/design for an
infrared comm module that can be attached to the pc motherboard. I
would like to communicate with a mobile device (or some other device
with ir). I found a couple of designs in the net- the design is very
simple, but when i checked for the availability of the IR
transceiver/receiver - i can't find it locally. I can't and probably
won't buy a single component from the net since the shipping alone
will be outrageously high. The design that I found has the tranceiver
and receiver on a single component. I've read that it has some chip of
some kind (i'm not really that sure).
The only available components are separated - they look like
LEDs. I would like to ask if there is an available schematic
diagram/design for an IR comm. device that uses these components. I'm
quite a begginner with electronics and I cannot design my own device.

Thank you very much for your help.

Aldous

If you just want something to use as a remote control for your
computer, check out a program called "Girder" you should be able to
find it with googe, it works really good, very flexible, you can teach
any remote and serial port reciever with it.

 

[Jerry Greenberg]

Most AC motors are dependent on the line frequency more than the
voltage. This type is a synchronous motor. If you had a supply that
can vary the line frequency to the motor this would allow to change
the speed. However, if the line frequency would go too low, the
windings in the motor would overheat. If it was to go much too high,
the motor may over speed, may overheat the bearings, if they cannot
take it.

If you vary the voltage to a synchronous motor, the torque will be
changed, not the velocity. Too much voltage will also overheat the
windings. If you make the voltage too low, the speed will decrease,
because of the internal friction in the motor, or the effect of the
load. If the voltage is lower than the rating of the motor, the speed
of the motor will also be unstable.

The type of supply that can vary the AC mains frequency to the motor,
would be fairly expensive, because of its complexity. You would be
best off to purchase a faster motor.

In simple words, you need a motor that is designed to do what you
want.

Jerry Greenberg
http://www.zoom-one.com

--




"Thomas G. Marshall" <tgm2tothe10thpower@hotmail.replaceTextWithNumber.com> wrote in message news:<QoTQa.2749$5G6.2161@nwrdny03.gnilink.net>...

tornado
generator, or just to see how far I can make it go without melting.

I understand D/C motors fairly well, but the A/C ones are a bit of a
mystery.

I know that voltage driven DC motors have their own alternator built in, so
that increasing voltage simply speeds the sucker up since the faster it
rotates, so does the alternation of the poles of the spinning magnet.

But in AC is fixed at 60hz (on this continent) and am wondering if the
various speeds of the fan have more to do with the number and placement of
the surrounding magnets per each setting on the fan.

Any ideas?

 

[Rich Grise]

"Thomas G. Marshall" <tgm2tothe10thpower@hotmail.replaceTextWithNumber.com> wrote in message news:<QoTQa.2749$5G6.2161@nwrdny03.gnilink.net>...

tornado
generator, or just to see how far I can make it go without melting.

I understand D/C motors fairly well, but the A/C ones are a bit of a
mystery.

I know that voltage driven DC motors have their own alternator built in, so
that increasing voltage simply speeds the sucker up since the faster it
rotates, so does the alternation of the poles of the spinning magnet.

But in AC is fixed at 60hz (on this continent) and am wondering if the
various speeds of the fan have more to do with the number and placement of
the surrounding magnets per each setting on the fan.

Any ideas?

Go to your local subwooferhead, borrow his 1000W amp, drive it with
a signal generator, and put the motor in place of the speaker. Be
very far away when you do this.

Good Luck!
Rich

 

[Dan Hollands]

There are time delay relays (time delay on dropout ) that will do this or
you could use a solid state relay with the control of the relay from the
fast dropout circult but with an electronic time delay before the loss of
input turns off the relay.

--
Dan Hollands
1104 State Road
Webster NY 14580
585-703-2963
QuickScore@USSailing.net
www.QuickScoreRace.com
"Chris W" <chrisw3@cox.net> wrote in message
news:3F158296.BFC52A27@cox.net...

I have a switch that cuts the power to 2 different AC circuits. I need
one of those two to stay on for a few seconds after the other is off.
Is there some easy circuit to do this. The current requirements are
about 15A at 110V

--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

 

[Larry]

Zeducious Monk <zeducious@hotmail.com> wrote in message news:<7og6hvoh6k7uit3eq1rc4p4n80dp275qdo@4ax.com>...

On 11 Jul 2003 09:12:12 -0700, aldous_b@yahoo.com (Aldous B) wrote:

hello,
I would like to ask if there is a schematic diagram/design for an
infrared comm module that can be attached to the pc motherboard. I
would like to communicate with a mobile device (or some other device
with ir). I found a couple of designs in the net- the design is very
simple, but when i checked for the availability of the IR
transceiver/receiver - i can't find it locally. I can't and probably
won't buy a single component from the net since the shipping alone
will be outrageously high. The design that I found has the tranceiver
and receiver on a single component. I've read that it has some chip of
some kind (i'm not really that sure).
The only available components are separated - they look like
LEDs. I would like to ask if there is an available schematic
diagram/design for an IR comm. device that uses these components. I'm
quite a begginner with electronics and I cannot design my own device.

Thank you very much for your help.

Aldous


If you just want something to use as a remote control for your
computer, check out a program called "Girder" you should be able to
find it with googe, it works really good, very flexible, you can teach
any remote and serial port reciever with it.

Find someone junking a remote control TV ect and or ask at a tv shop
for the guts to a set and a copy of the diagram around the IR pick up.
Use care around the CRT if its still under vacuum.

 

[Chris W]

Ok I found a time delay relay for sale on E-Bay
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2546108664&category=36328
now where do I find some kind of socket to plug the thing into so I can wire
it up?

Chris W

Dan Hollands wrote:

There are time delay relays (time delay on dropout ) that will do this or
you could use a solid state relay with the control of the relay from the
fast dropout circult but with an electronic time delay before the loss of
input turns off the relay.

--
Dan Hollands
1104 State Road
Webster NY 14580
585-703-2963
QuickScore@USSailing.net
www.QuickScoreRace.com
"Chris W" <chrisw3@cox.net> wrote in message
news:3F158296.BFC52A27@cox.net...
I have a switch that cuts the power to 2 different AC circuits. I need
one of those two to stay on for a few seconds after the other is off.
Is there some easy circuit to do this. The current requirements are
about 15A at 110V

--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

 

[Dan Hollands]

check www.digikey.com

--
Dan Hollands
1104 State Road
Webster NY 14580
585-703-2963
QuickScore@USSailing.net
www.QuickScoreRace.com
"Chris W" <chrisw3@cox.net> wrote in message
news:3F158296.BFC52A27@cox.net...

I have a switch that cuts the power to 2 different AC circuits. I need
one of those two to stay on for a few seconds after the other is off.
Is there some easy circuit to do this. The current requirements are
about 15A at 110V

--
Chris W

"They that can give up essential liberty
to obtain a little temporary safety
deserve neither liberty nor safety."
-- Benjamin Franklin, 1759 Historical Review of Pennsylvania

 

[N. Thornton]

"Robert Morein" <nowhere@nospam.com> wrote in message news:<Bl-dneRLTtXuU4WiU-KYvg@comcast.com>...

"Rich Grise" <richardgrise@yahoo.com> wrote in message
news:3df9fd6c.0307151613.3bb98b83@posting.google.com...
"Thomas G. Marshall"
tgm2tothe10thpower@hotmail.replaceTextWithNumber.com> wrote in message
news:<QoTQa.2749$5G6.2161@nwrdny03.gnilink.net>...
For fun I want to turn my a/c fan into a [possibly lethal] tornado
generator, or just to see how far I can make it go without melting.


Go to your local subwooferhead, borrow his 1000W amp, drive it with
a signal generator, and put the motor in place of the speaker. Be
very far away when you do this.

Since this will actually work, I just want to point out the potentially
lethal case of the fan blades separating.
Whatever they hit, they will cut llike a knife.

Probably more like a sharp meat cleaver wielded by a very large
psychopath. Oh, and they often bounce and fly off at unexpected
angles.

Regards, NT

 

[Sir Charles W. Shults III]

"Ronald Leenes" <support@macbrick.com> wrote in message
news:support-804592.18243420072003@news.tilbu1.nb.home.nl...

Hi,

for a project we have a very large key-matrix (32x24). We have a problem
with phantom keys (when three keys in a rectangle are pressed, also the
fourth corner is seen as pressed).

In any matrix system that is not properly isolated, it will be impossible to
avoid this problem. That is because pressing the corner key creates a path
between the two diagonal keys, and that is why your phantom key shows up.

How do we solve this problem? I know something can be done with diodes,
but we can't get it to work. Can somebody give some hints.

Typically, diodes are a good solution, but they are also slightly leaky.
This means that on small keypads, you should not have a problem, since there are
not many parallel diode on any given leg of the matrix. However, when you have
many keys in a matrix, the leakage currents quickly become quite significant.
The surest way to isolate this would be with parallel loaded shift
registers. One 8 bit register can be clocked to take a "snapshot" of 8 switches
on a single column with no leakage, phantoms, or unpredictable behaviors.
However, the circuitry can't be used with most matrix keypads- they are already
hard wired and not easily broken out to be used this way.

An additional problem is that the 'keyboard' consists of panels that can
only be opened with great difficulty.

Yes, that is a problem- meaning that you cannot open a common trace and run
it to a specific column outside of the keyboard. Well, you might try diode and
resistive solutions where each key has a fixed resistor in series, but once
again, this can be pretty difficult to do with most matrix keyboards.
Look inside a typical PC keyboard and you can see how they put over a
hundred keys together with a controller chip. Be prepared to program a
controller for your keyboard if you want key "rollover" and best isolation.

What is the most clever way to interface say 500 switches to a computer
(serial or usb)?

I would personally choose to completely forego matrix arrangements, when
given the choice. However, that is from trying to eliminate spurious signals in
robotics- a flaky sensory input can cause the machine to do crazy things. My
choice is parallel to serial shift registers, no more than 32 keys per column
(for speed), and go for 16 columns. That gives you 512 switches, read 16 bits
at a time. You end up reading 32 sixteen bit words and that can move pretty
quickly on USB.

Best regards,

Ronald

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

 

[John Popelish]

Ronald Leenes wrote:

Hi,

for a project we have a very large key-matrix (32x24). We have a problem
with phantom keys (when three keys in a rectangle are pressed, also the
fourth corner is seen as pressed).
How do we solve this problem? I know something can be done with diodes,
but we can't get it to work. Can somebody give some hints.

An additional problem is that the 'keyboard' consists of panels that can
only be opened with great difficulty.

What is the most clever way to interface say 500 switches to a computer
(serial or usb)?

Best regards,

Ronald

If you add a diode in series with each contact point (either in series
with each row trace and the contact point, or in series with each
column trace and the contact point) you eliminate the phantom keys.
This makes the flexible circuits lumpy, though.

--
John Popelish

 

[Thomas G. Marshall]

David Beijer <beijerdNOSPAMPLS@skynet.be> horrified us with:

Go to your local subwooferhead, borrow his 1000W amp, drive it with
a signal generator, and put the motor in place of the speaker. Be
very far away when you do this.

Since this will actually work, I just want to point out the
potentially lethal case of the fan blades separating.
Whatever they hit, they will cut llike a knife.


Probably more like a sharp meat cleaver wielded by a very large
psychopath. Oh, and they often bounce and fly off at unexpected
angles.

Not that I intent to try this out, but wouldn't the danger be smaller
when you use a fan with a cage around it?(Like most fans they sell
overhere) I mean, would the fan destroy that cage???

The fan I am going to genetically alter is plastic, within a plastic
housing. Metal ones are metal within a metal housing.

/Probably/ projectile free.....maybe.