Shredder

A shredder comprising:

• storage means for receiving a plurality of documents to be shredded;
• transport means for transporting the documents, at least one sheet by one sheet through separation of the documents;
• transport preventing means for preventing transport of an unsuitable document incapable of being shredded by said shredder;
• shredding blades for shredding the documents;
• a transport path for transporting the documents to the shredding blades;
• first detection means for detecting presence of the documents placed on said storage means;
• second detection means for detecting the documents, said second detection means being provided in said transport path;
• and
• a control circuit which stops operation of said transport means when the documents are being detected by said first detection means and when a signal indicative of absence of the documents has been outputted for a preset time period by said second detection means, said control circuit comprises a first operational amplifier for outputting in response to said first detection means, a signal to a drive circuit for driving said transport means, a second operational amplifier for outputting a signal in response to said second detection means, and a timer circuit responsive to said first and second operational amplifiers.