An alarm clock is a clock that indicates a pre-set time by producing sound at that time. This functionality of digital clock is used to awaken people or remind them [[wysiwyg_imageupload::]]of something. This circuit is an extension to the digital clock with time setting option. Here an extra switch is provided to set the alarm. While the alarm is set, the clock time does not stop and runs in the background.The circuit is build around 8051 microcontroller (AT89C51) and uses LCD to display time. This is an improved version of digital clock with LCD display. It has an extra feature to set the alarm in the starting. On reset, the LCD prompts the user to set alarm. Only the hour and minute components can be set by pressing the corresponding switches, repeatedly. These switches are made active low and so they provide ground to the corresponding input pins of the microcontroller AT89C51. The AM/PM mode is set by toggling the switch between ground and Vcc. Ground would set the clock in AM mode while Vcc would set it in PM mode.