Hi,
What small transformer does in ac 9v adapter while these type of transformers do not apply in ac input and what type of these transformer is and name?

I have a transformer it has 4 legs at input side and output has 2 legs. How can I use input legs?

pls guid me

 

It's impossible to know without seeing the circuit, but if this is a simple adapter that uses the transformer to step down the line voltage, and then has some rectifying diodes on the secondary side to get DC output, the 4 input legs probably support multiple voltages. For example, you could use 120V or 240V input depending how you wire the primary side.

 

Hi,
What small transformer does in ac 9v adapter while these type of transformers do not apply in ac input and what type of these transformer is and name?

I'm afraid the language barrier is too strong here. Maybe google translate could help.

I have a transformer it has 4 legs at input side and output has 2 legs. How can I use input legs?

it's impossible to know without seeing the datasheet, but it could be dual primaries (to be wound in series or parallel) or it could be a transformer with 3 input voltage taps.