Hi,

Where i live mains voltage is 120 volt. I have a step up transformer which can transform the voltage from 120 vol to 220 volt. I want to make it an accurate variable AC powersupply. Do i need a Rheostat or a variable resistor for it, and which one do you recommend from Amazon or another shop.

 

You don't mention how much current? The simple approach would be to buy an auto-transformer also called a variac and use that to drive your existing 120 to 220 volt transformer. Note the link is enclosed. Unless you are comfortable working with AC mains and understand the working of a variac (no mains isolation) I suggest a turn key off the shelf solution.

Ron

 

What do you mean by "accurate"?
If you mean "regulated" that's not easy to do for AC power.

 

You don't mention how much current? The simple approach would be to buy an auto-transformer also called a variac and use that to drive your existing 120 to 220 volt transformer. Note the link is enclosed. Unless you are comfortable working with AC mains and understand the working of a variac (no mains isolation) I suggest a turn key off the shelf solution.

Ron

Yes the Variac is good. If i connect it to the 120-220 transformer, the output of the transformer is isolated. I'll purchase the 5 amps version. Thanks Ron.

 

Just remember what Crutschow mentioned. This is not a regulated AC supply and it all hinges on your line voltage stability. Yes, following the transformer (120 to 220) You will have isolation.

Ron