rheostat capacity and inductor symbols
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a 5W 50R rheostat is rated to carry 316mA (max. current = sq.root[rheo wattage/resistance]) but a 5W 100R one will only carry 223mA. Think of it like fuse wire - if just the last turn carries too much current, the rheostat won't be producing 5W of heat, but that bit of wire will melt.
Power rating needed for a 200mA fan system with a 50R rheostat is IxIxR =2W, based on the current flowing with the fan at full speed. But if we used a 100R rheostat with the same fans the wattage would need to be 4W.
Power rating needed for a 200mA fan system with a 50R rheostat is IxIxR =2W, based on the current flowing with the fan at full speed. But if we used a 100R rheostat with the same fans the wattage would need to be 4W.
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