I just want to know if I take a 6-12v sine wave and put it in the reverse side of a step down transformer, will the voltage be amplified and the current will be reduced?

Thank you!

 

The voltage will be bigger at the output,yes . The maximum current you'll be able to draw will decrease.
Make sure you don't exceed the input voltage rating nor the output current rating.

 

One problem is that signal generators don't move enough current to drive a power transformer. I hope your source is beefier than a signal generator. If it is, this will work nicely. I use transformers backwards, regularly.