Op amps problem Gain Calculation

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)?
Click to expand...
Don't. use fewer keys and context switch, or use a virtual keyboard, it
would be cheaper than the hardware.

Al
 
"Thomas G. Marshall" <tgm2tothe10thpower@hotmail.replaceTextWithNumber.com> wrote in message news:<CoISa.21030$7O.2190@nwrdny01.gnilink.net>...
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.
Click to expand...


Along with the other notes read up on V/Hz Constant HP and over speeding
a motor and fan blade and for fun the idea that fan loading by
RPM goes up by the qube root. Kept yourself in one piece.
 
"Thomas G. Marshall" <tgm2tothe10thpower@hotmail.replaceTextWithNumber.com> wrote in message news:<CoISa.21030$7O.2190@nwrdny01.gnilink.net>...
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.
Click to expand...


Along with the other notes read up on V/Hz Constant HP and over speeding
a motor and fan blade and for fun the idea that fan loading by
RPM goes up by the qube root. Kept yourself in one piece.
 
"Arthur Jernberg" <stubby@comcast.net> wrote in message news:<rq6dnc3GU9vQ0IOiXTWJhA@comcast.com>...
Strange that most electronic manufactures have had very good preformance
using the IR LED design in their remote controls for many years. That is
unless you want the item to work in extremely noisy situations (I.E. where
there is a lot of florescent or ir sources already present), or if longer
ranges are necessary at which point you may consider an IR Laser as your
transmitter source.
"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.
Click to expand...


Another idea crossed my mind go to a computer repair site and
ask about a really junk laptop as they have had IR Tx/Rc for
quite a long time so some must be hitting the trash can.
 
"Sammy" <outofhereagain@ttt.com> wrote in message news:<oOSdnZ8uSpHl-rmiXTWJkA@comcast.com>...
Hi. I need a universal remote control that will access the MENU of a Emerson
tv. Model TC25550
I tried the "OneForAll 5", but that one only turns the tv on and off and
chan/vol.
I cant do a thing with this tv unless I can access the onscreen menu. Any
suggestions ?
Thanks.
Call all the TV shops in your area and see if you can buy a used
one from a junked set.
You can always get one from TV shop/factory, get ready to pay $40.00
to $60.00 for one. Hope it helps
Click to expand...
 
"Matt" <nutshell222@hotmail.com> wrote in message news:<I1Kdncp2pPoERbyiU-KYvg@warpdrive.net>...
I just purchased a new sony MP70 Car stereo, I have installed many stereo's
in the past and I"m having a specific problem with this one. I'm running no
additional equipment (ie. amps, subs, ect) just straight speakers. I
connected everything and the unit power's one correctly an plays at a low
volume, but when i turn the volume up the unit cuts out (no power) in a few
seconds it will come back on and unless i lower the volume it will keep
cutting out. Any suggestions?

Thanks in advance!



nutshell222@hotmail.com

Just a guess but sounds like a grounded or shorted speaker line
Unit may have a safety shutdown.
Also are speaker impedances correct for output lines?
Hope it helps
Click to expand...
 
Hi,

try looking @ http://www.gecw.co.kr/p23.htm
or download this directly: http://www.gecw.co.kr/data/SG24064A.zip

:)


"Luke" <Luke_Cawley@hotmail.com> wrote in message
news:4%mVa.95734$JA5.2104388@news.xtra.co.nz...
Hello everyone

I am having trouble finding a datasheet for a display module i have. I
tried
google so either my search technique is not good or it is hard to find. I
only know it is a 240x64 display module with a code on the bottom that
reads
SG24064A rev.2. Their are other markings on the underside including some
smd chips that i could name if required.

If anyone can helpit would be greatly appreciated

Luke
Click to expand...
 
miketinte wrote:
I want to overlay an image or text (perhaps through CC programming?)
on all channels of my home's cable system (NTSC). What's the simplest
way to do this? Has anyone done something similar to this before and
can offer some sage advice?
Click to expand...
Sort of...

http://www.decadenet.com/bob2/bob2.html
$79.95 each.
You program the text from your computer's serial port.
You would put one on each TV after the cable box, because it
has to work on baseband video not RF. I think this is the
simplest way and much cheaper than trying to do something with
each RF channel.
-Dan Barlow
 
Begin On Tue, 29 Jul 2003 13:17:40 +0000 (UTC) "David Porter"
<Fieldcottage@btinternet.com> wrote in Message id:
<bg5s5k$b42$1@hercules.btinternet.com>:

Can anyone tell me direct smt equivalent for the good old 1N914. Many
thanks.
Click to expand...
1N4148
 
Thanks for your response.

I was kind of going for a DIY (or solder yourself) type project.
Mainly because of costs involved with the pre-fab solution. Basically,
I want to display this image OVER the television show that is being
watched without any interruption. The trick here is, I want to inject
this image into the main splitter of my home's cable TV system. We've
gone almost totally DVD, so only one of the TVs in my house is a VCR
and anything involving a VCR is out of the question. How feasible is
this still?
 
miketinte wrote:
Thanks for your response.

I was kind of going for a DIY (or solder yourself) type project.
Mainly because of costs involved with the pre-fab solution. Basically,
I want to display this image OVER the television show that is being
watched without any interruption. The trick here is, I want to inject
this image into the main splitter of my home's cable TV system. We've
gone almost totally DVD, so only one of the TVs in my house is a VCR
and anything involving a VCR is out of the question. How feasible is
this still?
Click to expand...
I would say possible but even more expensive.
The signals in the cable aren't "lined up" in such a way that
you can affect all of them at once.

You would have to somehow separate out each channel, get it down
to baseband NTSC, detect sync, put in either your closed caption
message or your overlay, convert back to rf, and combine each
channel at its proper frequency.

You can do the first part with a big pile of surplus cable boxes.
The overlay you can build yourself but it's a bit complex.
I did a quick Google search and there are a few projects out there
but most people have gone to using a PC video capture and output
card to do this kind of thing.

You can get a whole pile of RF modulators cheap as surplus too,
but the channels will all come out as 3 or 4.

Getting channels shifted back up to their original "address"
is going to be interesting. There are circuits to frequency-
shift a channel but they're not mass-market so they tend to
be quite expensive.

http://www.tonercable.com/Toner%20Website/CatalogPages/SECTION%201/OLSON-OTM3550.pdf
http://www.multicominc.com/Manufacturer/Multicom/Catalog_page/page%208.pdf

Then you use a big reverse-splitter to combine all the outputs and shove
it into your house's cable.

I don't want to discourage you, but this is in fact a lot more
complicated than you'd expect. :(
-Dan Barlow
 
On Thu, 31 Jul 2003 19:44:56 -0400, Dan Barlow <danbarlow@radix.net>
Gave us:

miketinte wrote:
Thanks for your response.

I was kind of going for a DIY (or solder yourself) type project.
Mainly because of costs involved with the pre-fab solution. Basically,
I want to display this image OVER the television show that is being
watched without any interruption. The trick here is, I want to inject
this image into the main splitter of my home's cable TV system. We've
gone almost totally DVD, so only one of the TVs in my house is a VCR
and anything involving a VCR is out of the question. How feasible is
this still?

I would say possible but even more expensive.
The signals in the cable aren't "lined up" in such a way that
you can affect all of them at once.

You would have to somehow separate out each channel, get it down
to baseband NTSC, detect sync, put in either your closed caption
message or your overlay, convert back to rf, and combine each
channel at its proper frequency.

You can do the first part with a big pile of surplus cable boxes.
The overlay you can build yourself but it's a bit complex.
I did a quick Google search and there are a few projects out there
but most people have gone to using a PC video capture and output
card to do this kind of thing.

You can get a whole pile of RF modulators cheap as surplus too,
but the channels will all come out as 3 or 4.

Getting channels shifted back up to their original "address"
is going to be interesting. There are circuits to frequency-
shift a channel but they're not mass-market so they tend to
be quite expensive.

http://www.tonercable.com/Toner%20Website/CatalogPages/SECTION%201/OLSON-OTM3550.pdf
http://www.multicominc.com/Manufacturer/Multicom/Catalog_page/page%208.pdf

Then you use a big reverse-splitter to combine all the outputs and shove
it into your house's cable.

I don't want to discourage you, but this is in fact a lot more
complicated than you'd expect. :(
-Dan Barlow
Click to expand...

It isn't very feasible at all. If the cable is scrambled, it is
even worse a problem.
 
Send it in, it probably would be worth fixing but ask for an estimate before
having it repaired.
"FH" <nowaydude@hotmail.com> wrote in message
news:%0AWa.29991$Oz4.8857@rwcrnsc54...
i have a BU-80 that just made a pop sound and quit. is this something i
can
fix or do i need to send it to a shop? i had the volume on low and only
for
about 30 seconds... is it worth fixing generally?

thank you
Click to expand...
 
"Sammy" <outofhereagain@ttt.com> wrote in message news:<oOSdnZ8uSpHl-rmiXTWJkA@comcast.com>...
Hi. I need a universal remote control that will access the MENU of a Emerson
tv. Model TC25550
I tried the "OneForAll 5", but that one only turns the tv on and off and
chan/vol.
I cant do a thing with this tv unless I can access the onscreen menu. Any
suggestions ?
Thanks.
Click to expand...
Try ebay for a Sams Photofact of that TV? It should have specs for
remote control codes so that you can build a computer controller and
program the computer to 'talk' Emerson? Think 8 bit computer like
Atari or Comodore for this. Some of those 'universal' remotes were
capable of reading the codes directly and then just repeating them
as recorded. To program it you would fire old remote into the
universal, button for button. Five or six remotes later, you had
one remote with the codes for five or six devices. But you'd need
the Emerson remote to do that with.

Very unlikely you'll find a cheapy universal with the smarts to
operate the Emerson's menu, unless that is explicitly claimed
on the outside of the box it comes in.
 
PlugNET.uk

UK dedicated site related to Powerline data communications.

Do you have a project you want to take to market.or share with others???

Would you like a relationship with a company at the forefront and invest in
a Łb product or service in powerline datacomms?

Or you just want to find out the latest and take a look at the latest
gadgets out there.

www.plugnet.moonfruit.com
 
MMBT914 or MMBT4148 ( 1N914 chip in SOT-23) See On Semi, Diodes Inc,
Fairchild Semi, an a dozen others.

"none" <not@dev.nul> wrote in message
news:7n5fiv49f3nbdfl0fhqgqod6pjdte97rk1@4ax.com...
Begin On Tue, 29 Jul 2003 13:17:40 +0000 (UTC) "David Porter"
Fieldcottage@btinternet.com> wrote in Message id:
bg5s5k$b42$1@hercules.btinternet.com>:

Can anyone tell me direct smt equivalent for the good old 1N914. Many
thanks.

1N4148
Click to expand...
 
The 7809 might not work well with only 3v of drop. Look for a low dropout
type regulator. They can work with lower in-out voltage difference. For
3 watts dissipation, look for a 10 deg C per watt or less heat sink.

"Lawrence Lucier" <llucier@shaw.ca> wrote in message
news:3F331787.8BA20910@shaw.ca...
Howdy all..... :)

Has anyone a suggestion for a 3 terminal voltage regulator that
will take 12vdc input and output 9vdc @ 1A?

Any suggestions would be much appreciated...thanks! :)
Click to expand...
 
Brian Lund wrote:

Use a 7809 Voltage regulator


Maybe a little heatsink should be used also, there will be generated 3W of
heat :)


Brian


there is no 7809
Click to expand...
your choice is 7805, 7808, 7812
rw
 
7809s are available from Digi-key and Mouser.

On Mon, 11 Aug 2003 02:22:10 GMT, Rein Wiehler <rw@netscape.net>
wrote:

Brian Lund wrote:

Use a 7809 Voltage regulator


Maybe a little heatsink should be used also, there will be generated 3W of
heat :)


Brian


there is no 7809
your choice is 7805, 7808, 7812
rw
Click to expand...
 
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