i try te measure the ac current by microcontroller.
i put a 0.1 Ω and take the voltage drop across it.a 1 amp current make 0.1 volt .
i take it to a diffrence amplifier and then to a step up iron core transformer (100mA, 220/15) it produce 3.4 volt.(it step 0.1 volt to 3.4 ?????????)
HOW ??

 

say what ?

Can you please be more specific or post a post a picture of your circuit. It's very hard to understand where you are going and you need to be more precise

 

What exactly is your questions? Do you have any experience with circuitry? That seems like a pretty big "HOW?"

Also, if you are running 1 Amp of current through the transformer, use a core capable of handling the current, you list iron core transformer with 100 mA, 200/15 turns ratio.