>
> Please urgent help . This is a foolish question and nothing to do about
> pics but it is vital . What is the pin diagrams of a 7 segment cathod
> display . I mean HOW IS IT USED ?? . 5 volts to 100 ohms and then A-B-C ..
> etc but which pins are A-B-C .. . Please urgent help . I use HDSP 5503
>

For testing I'd proably stick for 220 ohms. You really can't hurt an LED
by reverse biasing it with low current. So simply rig up a probe with the
current limited +5 and ground and start poking on the display. Very quickly
something will light up. Since it's common cathode the ground pin will then
stay put. Use the CL +5 line to figure out the other segments.

Segments are normally labelled:

    a
  |---|
 f|   |b
  | g |
  -----
  |   |
 e|   | c
  -----
    d


Hope this helps. This is one task where you really don't need a pinout.

BAJ