Mellotronists

A friend of mine picked up a Wurlizter Sideman at a garage sale for 10.00. We fired the thing up and it has  some unique sounds. Apparently it is the first drum machine. It was made in 1962 and uses tubes to generate white noise. It has various filters to shape the sounds into different percusssion sounds. Does anyone on the list have any additional information on this?
                                  Jimmy Moore