The 555 timer IC is a very versatile and useful component and can be used for many things, from giving clock pulses to switch debouncing and as an output transducer. The basic 555 IC is housed in an 8-pin carrier, and these come astable multivibrator using 555 timer pdf DIL and SOIC formats. They run from 3-15V, and are generally quite hardy devices.
The 555 has 8 pins. The layout of these pins is shown to the right and the function of these pins in given in the table below. A low state on this pin resets the timer, which will not be enabled until the Pin goes high again.
This is used to adject the trigger voltage. Usually, it is unused, and is connected to ground to avoid noise in the circuit. This pin is connected to ground when the output goes low. This is used to control timing in certain applications.
The positive voltage supply to the chip. Must be between 3 and 15V. The basic 555 astable circuit is set up like this.