How to consume only 110v from 220v
I'm assuming you mean AC mains here, In which case you are looking for transformer.  A transformer is simply two windings on a magnetic core in your case you need one with a two to one ratio.

Luckily for you 220:110 is a common requirement and you should be able to buy one from your local builders merchant.  You need to ensure it has a suitable VA rating for the application.  Multiply the rated voltage of your equipment 110V by the rated current, this is the minimum VA rating needed.  Buy a transformer with at least this rating. The only downsides to buying one with an even larger VA rating are it will be heavier and cost more.