Two or three?
The encoders arrived today. I was really surprised when there were three encoders in the box and I only paid for two. One of them turns pretty roughly though, so it may not work. I will definitely need to replace the cables – the existing cables are about 6 inches long, and I need about 4 feet.
The power supply arrived also. It is a nice and shiny metal box with terminals on one end. Looks like it should do the job.