Can anyone help me with the circuit for an ac adapter?

Input: 220V AC
Output: 12V AC
Current: 1.5A

Professor expects to use power electronics application here without using ONLY using step down transformer. How to achieve this?

 

Welcome to AAC!

For schoolwork you need to show us your solution attempt before we can offer any guidance. Are you certain the output is AC? AC adapter often refers to AC to DC conversion.

 

Yes It's AC-AC. We tried dimmer circuit using diac triac, single phase ac voltage controller etc. Is there a better way to do it?

 

Is there a better way to do it?

IMO, the best way is to use a step down transformer, but your teacher wants you to use a more complicated method.

 

Can anyone help me with the circuit for an ac adapter?

Input: 220V AC
Output: 12V AC
Current: 1.5A

Professor expects to use power electronics application here without using ONLY using step down transformer. How to achieve this?

Hello there,

I am not sure that your description "power electronics application" is a good enough specification in order to proceed with this project because that phrase is open to very wide interpretation. I'll explain.

First, the modern trend in power adapters is to use a high frequency transformer by converting the input AC first into DC and then modulating it into a PWM wave then using the high frequency transformer to step down and then rectifying it and filtering it into a somewhat clean DC voltage. That's for a DC output however. Since your assignment calls for an AC output, a question arises as to what the output frequency can be, and since the specification of just "AC' is also subject to interpretation the question arises as to what constitutes an acceptable form of AC for the output, a pure sine wave, a synthesized sine wave, or an actual square wave output.
The synthesized sine would be a very good approach but not easy. It can be filtered to be very close to a pure sine too.
The square wave output would of course be the easiest.
Is it possible a capacitor drop circuit would be ok, sometimes called a transformerless power supply but this would be with an AC output so just really a capacitor to drop excess voltage.
Also, there is the two zener approach which would be the least efficient but still an option in some cases.

So you have to provide a little more information i think so we know what is allowed and what is not allowed.
If you dont know yet you may have to ask your professor.