Monostable Multivibrator Using 555
Category: 555 Timer IC
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
This circuit is designed and simulated in Proteus 7.10. In this circuit you will learn about the famous timer ic which is NE555. Many companies make this IC and there prefix can be changed but number will be 555, for example Texas Instruments make this IC with name LM555. Functionality will be same of both the IC's. So manufacturer doesn't matter unless the functionality is same. The 555 timer IC can be used in all multivibrator mode. It can be used as a) Astable multivibrator b) Monostable multivibrator c) Bistable multivibrator In this circuit 555 timer IC is used as monostable multivibrator mode. The astable mode was added previously and Bistable mode will be added in next circuit. Come back daily to get new circuit. The working of this circuit is given below. 1. Monostable mode means there will be one stable level and other is unstable level at the output. 2. The operating range of 555 timer IC is +5Vdc to 18Vdc. 3. An RC time (product of C2 and R1) is used to make the output for certain period of time. 4. The trigger pin is active low (1/3 of Vcc) and it will trigger the output at low or negative pulse. 5. In this circuit the trigger pin is pull up with resistor R4 of 10Kohm and a push button is placed between ground and trigger pin to give a trigger pulse. 6. In this circuit, the stable level is zero level, when a trigger pulse is applied the circuit goes to unstable state which is one state and after certain amount of time the circuit come back to its stable state which is zero state. 7. The monostable multivibrator can be understand by this animation. Application: 1. This circuit can be used as a timer for a specific period of time. 2. This circuit can be used as a timer for door bell.