Guys, i had attached the circuit diagram here.
If Or Gate output is 1 then transistor will be turned on so that relay will be turned on also. Now, if Or gate output is 0 , transistor will go off but relay will remain on until user remove the source voltage. But, i think there are some problems with my circuit because AND gate will be turned on when my OR gate output is approximately equal to 0( OR gate inputs: A connect to ground, B connect to Vcc=0V). This does not make sense. Vcc = 5 V. But now, output of OR gate still can turn on my Transistor.
In fact, an astable pulse will pass through AND gate when it is enabled. I measured the input of AND gate from relay, it is 1.2V. This voltage is enough to trigger AND gate and hence Astable signal can pass through AND GATE. This is not the result i want.
guys, please help!