how can we convert 220 VAC into 12V dc without using a transformer......i have studied bulk circuitary but is there any other method

 

There may be a way, but the transformer adds safety to the design by isolating you from the line voltage and current. Without some form of galvanic isolation, the idea is potentailly a lethal accident waiting to happen.

 

If you don't use a transformer, one of the output terminals might be "hot" unless you pliug the circuit the right way. You can use a "transformless" PSU (transformless so to speak), which is a power supply that uses a rectifier at the mains, and that DC voltage is pulsed at a higher frequency to supply a high frequency transformer. The advantage of this is that you keep the isolation, but you will use a much smallet transformer.

Other alternative consists on using an isolation transformer connected to the mains (1:1 ratio), as those are smaller than regular step-down transformers with the same VA rating, and feed the circuit from there.

 

Well you could convert the AC to light and shine it on a photocell. It does take a few cells but you can get that to 12V pretty easy. Getting the current up is harder.
*tongue in cheek though it will work*

If you absolutely HAVE to have that sort of supply:
http://www.onsemi.com/pub/Collateral/DN06011-D.PDF
Change the zener D7 to get the voltage you want. D6 is a 30V zener, change that to something appropriate for over voltage or remove it and install a fuse.

BTW the 2nd circuit uses light too!