a method is shown providing a bill validator that is adaptable for bill payback by utilizing an attachable bill hopper module to fit between the bill stacker and the bill validator . a construction is shown providing a bill validator utilizing an attachable bill hopper module fitted between the bill stacker and the bill validator that fits in the same “ envelope ” with an existing bill validator with stacker . a method and construction is shown where higher bill security is provided when the power is off . a method and construction is shown where higher bill security is provided when humidity and icing occur in and around the inlet .