30 Sep '16, 11pm
DIY Watt-Balance Redefines Your Kilograms From Scratch
A watt-balance doesn’t look or operate much different from a regular balance, only instead of weighing an unknown mass against a calibrated counterweight, a watt-balance employs a calibrated electromagnetic counterforce. That force is produced by an electromagnetic actuator. [Grady] scratch-built his watt-balance from wood, however, even though he carefully turned and wound his own coils for the electromagnets, he cannot be quite sure about the exact amount of force his actuators exercise per ampere of consumed current. Before a watt-balance weighs redefined kilograms, the contraption needs to be calibrated.