Driver to drive?

nospam wrote:

So for a 348 LED display you need 3 A6276ELW chips, 8 suitable P channel
MOSFETS, something like a 74HC4051 to drive them and a (big if you want
bright) 5v power supply.
Click to expand...
I've had a quick look at the data sheets, and 16 pin output would
certainly require less chips, but I don't understand what MOSFETs are,
or what(/how) to use the 74HC4051 for :-\

Daisy-chaining loads of 595's (or 74HCT259's as suggested in the .basic
group) looks easy - are there any advantages/disadvantages to the method
you suggest over this?

Thanks,
--
Danny
 
CFoley1064 wrote:
Look up the datasheet for the 74HC595.
Click to expand...
Another quick (possibly dumb) question...

If you go to www.rswww.com (the URL has a session ID, so prob won't
work!) and search for the 74HC595, and click through to the product
page, it lists several:

MC74HC595AN
SN74HC595N
74HC595D

but I don't understand the differences between them (there's a hefty
price difference!). What am I missing?

Thanks,
 
Subject: Re: Controlling hundreds of LEDs
From: Danny T danny@nospam.oops
Date: 12/21/2004 3:22 PM Central Standard Time
Message-id: <41c8941b$0$20913$ed2619ec@ptn-nntp-reader02.plus.net

snip
Yeah, I posted there too, unsure exactly which was best. Had good
answers from both. Thanks :)

Danny
Click to expand...
Hi, Danny. I'll post answers on s.e.b. This is really too basic for this
forum.

Chris
 
In article <5QXxd.7855$yK.3612@newsread3.news.atl.earthlink.net>,
see@sig.com says...

"Dick" <dick@langwang.demon.co.uk> wrote
My Tek 465 scope has developed a minor but annoying fault in its
triggering circuitry

It sounds (reads) like a bad connection.

By Ole Occam's razor, and a description of the problem - 'it works
till I touch the knob' - my first guess is a dirty and/or worn
synch selection switch or trigger level pot. The pot wouldn't
happen to have one section for Ch. A and one for B and get
bypassed in Auto, would it?

If it were mine, I would first try a spritz of contact cleaner into
the switch via the front panel slot (IIR465C). All contact
cleaners are the same - mineral oil and alcohol - so the cheapest
Radio Shack stuff works as well as anything. WD40 also works well.
Click to expand...
NONONONONONONO!!!! DEFINITELY NOT!!!!!

All contact cleaners ARE NOT the same! Never have been, never will
be, and the proper ones for degreasing electronic equipment do NOT
contain any mineral oil!

I speak from knowledge gained over 25+ years of pro experience in
the fields of radio, electronics, and computers. NEVER, under ANY
conditions, use WD40 inside a Tektronix 'scope or any other electronic
device! It leaves an oily residue which will actually ATTRACT dirt and
gunge, and make the problem worse.

If you value your test equipment, don't cut corners on the stuff
you use to maintain it. Check the Tektronix service manual for the
recommended cleaner formulation, and get it from a quality electronics
supply place (Radio Shack does NOT come under that category as far as
I'm concerned).

I can tell you from personal experience that CRC 'CO Contact
Cleaner' works very well, and it is plastic-safe so you won't damage the
innards of the vertical attenuator assemblies.

It may cost a little more up front, or be a little harder to find,
but you won't be risking the long-term life of said equipment.

Happy hunting.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"


-----------== Posted via Newsfeed.Com - Uncensored Usenet News ==----------
http://www.newsfeed.com The #1 Newsgroup Service in the World!
-----= Over 100,000 Newsgroups - Unlimited Fast Downloads - 19 Servers =-----
 
A number of the switches on the 465 use PC board pads as contacts. They
have heavy gold plating, but eventually the gold wears off. When that
happens, the switch is dead and as far as I know can't be repaired. You
might be able to squeeze a little more life out of it by cleaning, but
in any case I'd be very careful not to use a cleaner with any abrasive
qualities. If cleaning doesn't cure the problem, worn pads might be the
cause.

But by all means check with the 'scope newsgroup. I'm sure you'll find
folks who have had a lot of experience with the 465, and some might even
know of some kind of fix or replacement for worn switch contact pads.

Roy Lewallen, W7EL
 
"Highland Ham" <abcgm0csz.kn6whxyz@abcntlworldxyz.com> wrote in
news:mB_xd.352$nE.14@newsfe3-win.ntli.net:

If it were mine, I would first try a spritz of contact cleaner into
the switch via the front panel slot (IIR465C). All contact
cleaners are the same - mineral oil and alcohol - so the cheapest
Radio Shack stuff works as well as anything. WD40 also works well.
==============================
On various occsasions I have been told that WD40 is NOT the right
cleaning agent for electrical systems involving plastic insulation re
wiring, etc. I always use (non chlorinated) contact cleaner as
available from Rat Shack and similar stores.
Here in the UK I use contact cleaner supplied by Maplin.

Frank GM0CSZ / KN6WH
Click to expand...
On TEK LF or HF cam style contact switches,do NOT use mineral oil-based
cleaner/lubes.Take some 99% isopropyl alco,wet a narrow paper strip,and
slide under the closed contact,and move back and forth.These cam-style
switches have VERY low wiping force,and any oil,grease,or film will cause
intermittents or opens.

I suspect a calibration may improve his triggering,too.

--
Jim Yanik
jyanik-at-kua.net
 
Don Lancaster <don@tinaja.com> wrote in news:41C84E44.C75885D7@tinaja.com:



Clean the switches with Radio Shack tuner cleaner.
Click to expand...
No.Use 99% isopropyl alcohol.

--
Jim Yanik
jyanik-at-kua.net
 
"Lou Pecora" <pecora@anvil.nrl.navy.mil> wrote

Not to simulate, temperature as the system itself.

That doesn't make sense. It's the temperature of 'something.' What's
the something?
Click to expand...
Anything. A bad way of saying the universe is chaotic, and one can
pick any old measurement of it as an example: The temperature goes
up and down, staying within bounds and is only predictable in the
general sense.

Chaos is safe; order is dangerous. Although I imagine with a .mil
address you won't quite agree with that sentiment.

The universe also has a random factor so maybe chaotic isn't
the right category of things fuzzy.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
 
<metasynths@netscape.net> wrote
has anyone created a chaotic circuit in
SPICE?
Click to expand...
The model may quickly run into precision limits and
produce false results.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
 
Danny T <danny@nospam.oops> wrote:

nospam wrote:

So for a 348 LED display you need 3 A6276ELW chips, 8 suitable P channel
MOSFETS, something like a 74HC4051 to drive them and a (big if you want
bright) 5v power supply.

I've had a quick look at the data sheets, and 16 pin output would
certainly require less chips, but I don't understand what MOSFETs are,
or what(/how) to use the 74HC4051 for :-\

Daisy-chaining loads of 595's (or 74HCT259's as suggested in the .basic
group) looks easy - are there any advantages/disadvantages to the method
you suggest over this?
Click to expand...
Yes. Driving 384 LEDs requires 4 chips and 8 3 pin transistors (MOSFETS)
instead of 48 chips and 384 resistors. Depending on how you want to
physically arrange the LEDs it can reduce the required wiring by a factor
of 8 also.

Search the web for LED, matrix, and multiplex. You should something that
gives you the idea.
 
On Tue, 21 Dec 2004 14:28:56 -0600, Leon Sorokin wrote:

thanks for the advice. i now realize i have a lot of reading to do.

the project is for my girlfriend, she does track and cross country and goes
out running at night and needed some sort of bright flashing indicator. and
being an active Luxeon LED flashlight modder on CandlePowerForums, of course
i decided to do some research into the possibility of building a low-cost,
light-weight, good temp range (for winter running), vibration based flashing
circuit to avoid using a switch and the annoyance of turning the circuit on
and off and just have it flash on impact.
Click to expand...
What ever happened to those flashing shoes? One of those with some really
lightweight wire would make a pretty good trigger. And I've seen
bicyclists with a hazard flasher on their helmet, but that'd be pretty
heavy.

Good Luck!
Rich
 
if you need,i can do it for you .
DC Voltage input:1--50.0V
DC Current input:0.1--50A
Max Power:600W(work for ever) / 700W(work in tem minutes)
http://www.super_tech.nease.net/cpjs1c.htm
Model:ST-SC6001
 
John Fields wrote:

Probably a good place to start is by defining the size of the
characters you want to display, and a 5X7 matrix works nicely unless
you want to get fancy
snip
Click to expand...

Sorry John, I should've been slightly less vague! Scrolling text was an
example, but I'd like to be able to play things other than text (or
maybe scroll the other way, etc.). In fact, Blikenlights is probably a
better example of what I want to do!

Your example would work fine, but as I understand, it would only allow
shifting columns along, and not let me define individual pixels?
 
Rich Grise wrote:

Of course, if he does intend to scroll it, then you'd want them all there,
and then you get to spend the next 3 months writing the software! ;-)
Click to expand...
This is another obstacle... I've never written assembly in my life...
PIC Programmer coming this week, and I've no idea how much I can fit
into a PIC16F627 chip.... Pong anyone?
--
Danny
 
Danny T <danny@nospam.oops> wrote:
Hi All,

I'm trying to control hundreds of LEDs from my parallel port (8 data
pins - will soon be replaced with the output of a programmed PIC, also 8
pins).

I'm not an electronics guy (I'm a software developer), so trying to
control x00's of LEDs from 8 pins looks a bit tricky...
Click to expand...
Xilinx has a nice report for a project with many LED in one of the last
Xilinx journals.

Bye

--
Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
 
On Wed, 22 Dec 2004 03:02:14 GMT, "Nicholas O. Lindan" <see@sig.com> wroth:

metasynths@netscape.net> wrote
has anyone created a chaotic circuit in
SPICE?

The model may quickly run into precision limits and
produce false results.
Click to expand...
I have a spice model that demonstrates chaos. The simulation will run
as long as you care to let it run and will produce chaotic results that are
stable.

Jim
 
I read in sci.electronics.design that John Bailey
<john_bailey@rochester.rr.com> wrote (in <41c961e9.30717838@news-
server.rochester.rr.com>) about 'Neato chaotic equations for analog
computers to display?', on Wed, 22 Dec 2004:
There was a useful thread on sci.fractals in 1997
Click to expand...
Are all the threads on that group infinitely long? (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
Frank Bemelman wrote:
Of course, for a display in a waiting room, nobody will complain,
not about that anyway ;)
Click to expand...
LOL! I gave that as an example cos my doctors have one - I'm not
building them one! :)

I got my, erm, PIC Programmer today... I should've paid more attention
to eht word "Kit" in the title... Just had to buy a soldering iron...
Think this'll keep me busy for a few weeks yet... ;o)
 
Frank Bemelman wrote:

Sure you can define individual pixels. The idea is to keep a copy in
memory, change the 'pixels' there, then reload the entire chain of
shiftregisters with the new pixels. On a PC LPT port you can do this at,
let's say, 100KHz. On a PIC it could be 500KHz. Reloading 100 columns
would take 1ms or less.
Click to expand...
I think I get it now. I was expecting each bit to be "output" with each
shift, but that's not so. I can keep shifting until I've done all the
columns, then have them output in one go :)

--
Danny
 
Nicholas O. Lindan wrote:

metasynths@netscape.net> wrote

has anyone created a chaotic circuit in
SPICE?


The model may quickly run into precision limits and
produce false results.
Click to expand...
"False results?" What does that mean? Is there a 'true' result? If
you ACTUALLY built a chaotic oscillator out of ACTUAL electronic
components and started it up, would its result be true? How about if
you built two of them, and tried your very hardest to start them both up
under the same identical conditions, would they both continue to produce
the same output forever? If not, which one would be the 'true' one?

-- Foo!
 
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