This circuit we applied IC 555 timer for control outside deviced .In This time we control Lamp ON/OFF .After presses botton SW 15 second IC 555 which connect mode monostable mode will Generators Pulse output signal "LOW" for trigger Triac . The Triac will stop state and Lamp Close
Figure1 Schematic of 15 second timer
We can caculate Timer by fomular : T = 1.1 X R X C …in second
15 second timer 
