UCN5804 erratic behaviour

[the_warper]

Hello all,
I am working on my engineering project which requires to drive two stepper motors.
For this purpose I use 2  ucn5804 's. I am using a battery eliminator for the +12v supply to the motors, and I'm using used 9v batteries to supply the +5v for the IC's. Everything was fine until awhile ago. The motors stopped working or behaved erratically. It was wierd. Upon investigation, it seemed that the 9v batteries were drained. I tried replacing them with new ones, but the motors don't respond.

However when I use a battrery which is half drained, it responds. Very confusing.  ???

Also I am using a common ground for the 9v(UCN5804), battery eliminator, and the parallel port control.

Any ideas?
Thanks in advance.
the_warper

[ante]

You have to use a stabilized 5V for the IC