Preheat the waffle iron. Melt the butter over low heat in a (1 Qt.) saucepan. Set aside to cool. Combine the flour, baking powder, baking soda and salt in a large bowl. Beat the buttermilk into the butter. Beat in the eggs. Beat the butter mixture into the flour mixture. Ladle enough of the batter into the waffle iron to cover two third of its surface. Use a spatula to spread the batter to the edges. Close the lid. Cook until the steam stops (about 5 minutes). Open the lid. Use a fork to remove the waffle. Continue with the remaining batter.