Based on the LM555 Timer Chip a highly stable device for generating accurate time delays or oscillation. when a switch is turned on or off mechanical bounce noise generates spurious pulses. When operated in monostable mode the EBTD9 prevents these noise pulses from adversely affecting your project. Use this circuit to set clocks or counters any time you need a pushbutton switch! Or run the kit in astable mode and learn how clock/timer oscillator circuits work. Use this circuit to clock other projects.