74ls47 worked on common anode why not work on common cathode?

[Brilliant16]

I did a project 7 segment with common anode but this did not work on common cathode.
What's the reason of this.Can someone help me?

 

[BradtheRad]

If you were to hook up an external inverting device to each of the 7447's output pins, you could make it work with the other kind of led display.

The internals of the 7447 are made to work on positive logic. Small version of image at:

The final devices produce a positive signal to turn on an led. However by using 7 transistors or 7 inverters, you can convert these outputs to negative logic.