Emulation (Was: Emulators of Classic Computers) - test-drb@ccmp.vtda.org

15 Jan 2004

On Jan 16,  4:43, der Mouse wrote:
...
  >> What indeed...  Now, Maplin do some nice 13mm
LEDs, how big do you
 >> think we could make a panel?  How about the 3" LED clusters they use
...
    as tail lights on buses round here?  Make a PDP-8
6' across, like
 the giant MS-20 that Korg made for demo tours in the 1970s?  But then you'll
need the MIG welder again :-) 
 Details, details. :)
 Actually, I'm a bit interested in the other direction: how _small_
 do/can LEDs get?  (And how much heat do they produce?)  I've been
 pondering something, but in order for it to be workable I need to be
 able to cover fairly large areas with some kind of display technology
 at a resolution no worse than about 75dpi.  Since "large areas" means
 dozens of square feet, too large for a CRT, all I've been able to think
...
  of are LEDs.  But I don't know how practical (or
more likely how
 drastically impractical) that is. 
Interesting...  Smallest I've seen are surface mount, about 0.1" x
0.05".  Not small enough for 75dpi, but perhaps you can get smaller
arrays.  However, even LCD displays for laptops are only about 75 dpi,
and I suspect you'd get gaps between the arrays.
Power?  Well, rule of thumb is around 2V across an LED, at around 10mA,
depending on the type and brightness you want.  Suppose you used the
surface mount types I've seen, that would be 10 x 20 = 200 in a square
inch; at 10mA each that's 2A at 2V = 4W, or about 576W per square foot.
 I don't know offhand what the efficiency of an LED is, but a few of
those would make a reasonable room heater :-)  Of course, you could
multiplex them and cut the power to maybe 10%-20% of that.
--
Pete                                            Peter Turnbull
                                                Network Manager
                                                University of York