FelixFelicis:
kk..I will use a diode.Is it advisable to use a single 6v supply to all these components? Or should I use 2 separate power supplies?
Well I would try it with just one. If you have problems due to electrical motor noise you can either add some filtering capacitors or go with two 6volt battery packs. Sometime you just have to try stuff to see how it's going to work out rather then make all the perfect decisions from the start. 
Lefty