Hi,
. I was totally shocked after seeing this. Can you explain me this one also)
General rule:
Don't leave any inputs floating, neither at digital ICs nor at analog ICs...as long as it is not mentioned otherwise in the datasheet.
Floating means the voltage level is
undefined, it may be true Low, it may be true High, it may be in the "unallowed" area between Low and High (causing increased supply current), it may even oscillate.
Even when there is no notice in the datasheet you must not leave them floating.
But in this case the datasheet clearly mentiones:
Provide a 5-V supply to VCC1 and valid logic input levels to data and enable inputs.
Your circuit:
Datasheet says:
Bypass capacitors of 0.1 uF or greater should be used at VCC1 and VCC2 pins.
They are missing.They are for fast edges.
Also you need proper electrolytics bulk capacitors. They need to store the energy of the inductive motor when switched Off.
An overvoltage suppression is also a good idea.
Extra capacitors are needed for the 7404 and the MT8870.
Your PCB should contain a solid GND plane. Don't use a breadboard.
Klaus