A rotary converter, which converts AC electricity to DC electricity is a largely obselete technology. However you can still buy them in a wide range of sizes. The cost depends upon their size and capacity. A small 5 hp device would cost around 400$. A 25 hp rotary converter costs around 2800$ and they go up from there.
You can buy a rotary phase converter on home depot, Lowe's or online on http://www.americanrotary.com/
A rotary converter is a mechanical rectifier. A rotery converter is ment to convert AC power to DC power or DC to AC.
Induction motor
It's generally better to just buy a rotary phase converter, as they are very complex.
A rotary phase converter is a device that changes single phase electrical power into multiple phase electrical power.
A rotary phase converter is commonly used to convert a single phase electrical power source to three phases. This allows you to use three phases instead of one.
Rotary actuators average around $100 to replace. They are important because they move the read/write head to the proper data track.
On average, I spend 40 dollars for these software. You'd better google amv converter to confirm it.
The average cost of a digital TV converter is around $30-$40. However you can find digital TV converters for less money if they are used.
To figure out what size rotary phase converter you need to figure out what type of equipment you have, how difficult is to start, and the AMP requirements of it. With this knowledge you can go to any company that sells rotary phase converters and figure out which one you need. http://www.rotaryphaseconverter.info/selectingrightsizerotaryphaseconverter.htm
That converter costs about $100
The average cost to replace a catalytic converter on a 1994 Cadillac DeVille is $700. This includes both the parts and labor.