The 555 timer IC was first introduced arround 1971 by the Signetics Corporation as theSE555/NE555 and was called “The IC Time Machine” and was also the very first and onlycommercial timer ic available. It provided circuit designers and hobby tinkerers with a relativelycheap, stable, and user-friendly integrated circuit for both monostable and astable applications.Since this device was first made commercially available, a myrad of novel and unique circuitshave been developed and presented in several trade, professional, and hobby publications. Thepast ten years some manufacturers stopped making these timers because of competition or other reasons. Yet other companies, like NTE (a subdivision of Philips) picked up where some left off.