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Please reconcile-- your question appears impracticable!!
With only passive R and C how do you propose to have DC-DC boost converter?
However, as you have put this question in micro-controller section, I suggest that you create a charge pump using the clock output from Micro, driving a FET or a transistor with an inductor in the collector circuit. From the collector, rectify using a 1N4148 ad filter you get high voltage DC.
You can use a 12V regulator like 78L12 or a resistor and zener to bring it to a wanted supply. However it can deliver few mA but not much.
Friends, thanks for ur replies. Actually, my need is to interface 4 inch seven segment displays with the microcontroller.I want to control the segments with transistors.I require an output of 12v from the transistors, which is to be given to the common anode of the displays.I have used CL100,BC547,2N3906,2N2222 transistors. Iam unable to control the segment with the transistor's base(output from the microcontroller). My need is, if I give "High(5v)" from the controller, I require 12v dc output to light uo the segments. If I give low, the segments should OFF. Plz give me ur kind suggestions to do so.