Since they aren't allowed to get electricity from the utilities, a lot of the Amish around here have solar panels on their barns and outbuildings. They use the power for well pumps, power tools and lighting in the buildings. Same with gas, can't use natural gas, but can use propane.
The local Amish welding/fabrication shop I frequent is pretty large, four buildings I think, powered by a diesel generator. A while back I heard an electric calculator on one of the offices, and recently I saw an old word processor unit setting on the customer service desk. They have a telephone/answering machine and a fax machine in the neighbor's garage across the street, and now several of them carry cell phones.
It all depends on the how liberal the local bishop is as to what they can use.
They aren't allowed to have cars or trucks, so a couple of the local Amish building contractors pull their equipment/supply trailers from job to job with a tractor. I see them tooling down US20 occasionally.