555 timer IC is commonly used in monostable mode to generate a pulse every time a trigger is given. The project described here uses NAND gate for [[wysiwyg_imageupload::]]monostable operation and thereby avoiding the need of 555 timer.The circuit in the project uses IC 7400, which has four inbuilt NAND gates. Here we have used the first and second NAND gate of the IC 7400. Suppose, initially the trigger input T is High at a logic level “1” so that the output from first gate (U1) is Low at logic level “0”. The resistor, R will cause the capacitor, C to charge or discharge. The output from the second NAND gate (U2), which is connected as an inverting NOT gate is also fed back to the input of U1,which  is at logic level “1”. Since both junction V1 and the output of U1 are both at logic “0” no current flows in the capacitor C and this results in the circuit being Stable and will remain in this state until the trigger input T changes.