Electrical, electronic engineer and technician working many device and circuit have a common ic every where need this ic 555, 7555 timer circuit, pulse generator and triggering and many more controller circuit use this IC The 555 solid timing circuit is an exceedingly steady controller fit of handling faultless time postponements, or swaying. In the time delay mode of operation, the time is decisively controlled by one external resistor, diode and capacitor. For a stable operation showing oscillator wave value the free running recurrence and the obligation cycle are both exactly