large display question

At like $80.00 US, a Gameboy Advance would do nicely. There are free tools
online as well.

Mike

Mike,

I guess I did not make another requirement clear. This robot is pretty
large, and I would like observers to be able to see the screen from,
say, 30-50 feet.


Jake.

With this throw distance it's pretty obvious you can't do anything at
normal resolutions and not go into a very large screen (35 inches or
more). Check out the Web sites on home theater and you'll find some
details on how to calculate minimum screen sizes for different viewing
distances. I'd say a rule of thumb is no less than 10-12" per 10 feet,
if you want the audience to see any detail at all.

Some large LEDs in a simple pattern seem to be the way to go, which can
be used for general mood display. It's pretty easy to make a smile or
frown out of some high-brightness LEDs laid out in a bow-tie
arrangement. Or you might get fancy and have the robot project something
onto the floor, ceiling, or nearby screen, disco-like.

-- Gordon

Gordon,

Thanks, it looks like an LED display is a very good idea. Are there any
display that can be addressed directly through an RS-232 or equivalent
?

Jake.

Si offered a pretty good URL for a LED message board if this is the way
you want to go. There are a several companies that sell these, and a
Google search should turn up a bunch.

Try to find one that A) runs of 12 volts (not directly 110 volts, since
that's a hassle for a mobile robot) and B) allows you to program in
graphics.

Nuts & Volts magazine has run an article here and there on building one
of these, if you want to go that route. Check their back issues.

-- Gordon

Thank you Gordon.

Jake.

Where are you located? I have 3 of the Adaptive Microsystems LED signs
that are mostly taking up space in my garage. These are 36" x 2"
matrices of red LED's. They are designed to run on 8VAC but will run on
8 or 9 VDC. They use the 60 hz signal for running the internal clock and
I think for timing the moving display operation. They were originally
sold with power transformers that would supply about 5 amps as I
remember. They will accept RS485 serial data in. I don't have any docs
on them or their protocol. I also don't have the power transformers for
them. If you can pick them up in the Phoenix, AZ USA area, I will trade
you a sixpack of a good stout for all three.

Bob

Thank you for the offer Bob. I am a little far away though, in TX
actually. But I am sure that somebody closer might see this thread and
get you that beer.

Jake.

You may want to look at the below betabrite signs and similar LED
types of signs. There are  inexpensive chips and info on the net
for driving these types of signs from the serial port. I've seen
these on ebay and some surplus sites.

http://www.betabrite.com/

Thank you Si.


Jake.