I've made the eddy current brake. It has about 14 m of 20 AWG magnet wire wound about a chain link. It has about 0.5 ohm resistance.
I tested it by holding the disk spinning at about 450 rpm in the slot of the chain link. The magnet was in my hand. I briefly applied about 10 V from a 30 A variable power supply. I felt NO FORCE during the time the coil was energized. It got warm within seconds so there was a lot of current ( my calculations tell me about 20 A) flowing through the coil. At this point I call my eddy current brake a failed experiment. It could be the magnet, it could be the low RPM or the thin aluminum plate.
Rumbling and whining:
This thing was hard to make and it didn't work. I had to buy magnet wire on line, drive to buy a chain in the store, drive to the beach to get sand for annealing process. I've spent about 40 minutes heating the chain in the sand with a propane torch which after all probably didn't change the magnetic properties of the metal much but made it a lot softer to cut and bend. I had to unspool the wire to a larger spool so I can measure how much wire I will be winding which took about an hour. Hours of research on winding magnets, trying to figure out wire resistance, max currents, weight and other crap. Then I had to wind the coil which took me about two hours. I didn't want to connect it to the power supply directly since it had such a low resistance so I had to wire some resistors in parallel to lower the overall resistance because I didn't have any low ohm resistors. Wire the coil with resistors and a switch in series. Connect it to the power supply. At this point I think my meter died because I tried measuring current through the low current connector. My 30 A power supply's current indicator also died! After all that work I get no force whatsoever from the brake. At this point I think I need to take a chill pill called fu*kitall and move on to a different type of brake.