Bistable 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 bistable multivibrator mode. The astable and monostable mode was added previously. Come back daily to get new circuit. The working of this circuit is given below. 1. Bistable mode means there will be two stable levels and none is unstable level at the output. The circuit maintains its output untill external trigger applies. 2. The operating range of 555 timer IC is +5Vdc to 18Vdc. 3. No RC time (product of C2 and R1) is used, because we want stable states. The only external trigger changes output and that output will remain unchanged untill next trigger comes. 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 connected with pin 6 and also connected with output through resistor R5 of 10Kohm and a push button, a capacitor C2 of 100nF is placed between ground and common point of R5 and push button to give a trigger pulse. Applications: 1. This circuit is used to understand how bistable multivibrator works. 2. This circuit can be used to manually change the output levels.