An method for determining the denomination of a coin with a disk-type coin processing system comprises moving a coin along a coin path with a rotatable disk, generating an encoder pulse for each incremental movement of the rotatable disk, directing a light beam transverse the coin path, detecting the light beam with a light detector, developing a signal at the light detector indicating the presence of a coin in the coin path, counting a number of encoder pulses occurring while developing the signal at the light detector, and comparing the counted number of encoder pulses to a plurality of stored numbers of encoder pulses corresponding to the particular coin denominations.