Most of us have lots of electronic devices that require power. Some need 12 volts, like car accessories. Others use 5, 6, or 9 volts and sometimes other voltages. If we want to use the electricity from our power outlets at hoe, we have to transform the 120 volts into smaller voltage. A step down transformer is handy in these circumstances.
Here is a short video to acquaint you with step down types:
Step down transformer/power supply. (provided)
Look at the case of your power supply/transformer and see what the specifications are. Is it a step up or step down transformer? What is the ratio? See if you can measure the resistance of the primary (where you plug it in).
PLEASE RESPOND: What did you find out? Scout around to see if you can look at another power supply you might have. What can you determine about the transformers in each?