Eisler was born in Vienna, Austria. He was a student at Vienna University of Technology. German nationalists would not let Eisler get a job in Vienna, because he was Jewish. He got a job with an English company (Gramaphone Company, EMI from March 1931). He removed interference from music broadcast on trains. He moved to England but was sent to an internment camp during WWII. Eventually, his circuit boards for the Americans helped defeat German V-1 flying bombs.