I have a coin counter bank I bought at the mall. It doesn't actually sort the coins, but it does count an amount of what you've put into it.
When you insert a coin, you push it through a set of rollers. As you press it in, one roller moves over widening the space as the coin goes through. On the inside, the roller hits different switches. Depending on how far the roller is moved (diameter of coin), contacts are closed and the coins amount is added in the circuitry and displayed on an LCD.
I dont have a schematic, but maybe this description will help with a design.
I have seen some mechancal type sorters that have a rotating disk. The coins are put into a funnel at the top and one at a time, the coins go into a notch in the disk. The disk spins and below it are 4 holes. First is dime, then penny, then nickle, then quarter. If the coin is a quarter, it passes over the first three holes because they are too small.
Other sorters Ive seen go by a coins weight and as each coin rolls through, different tilting platforms let the coin fall off the right side and into containers.
Hope this helps...
~Mike