EasyElectronics

  Application of IC 555 as an Astable Multivibrator           An astable multivibrator can generate vibrating output between high and low voltage hence called as astable output as there is no stable state. It is also known as a free running multivibrator.       That means it is oscillating from one state to another hence it is called as astable mode , and it produces rectangular output signal. Fig. – Circuit Diagram of IC 555 as Astable multivibrator Fig. Working of internal transistor with external capacitor Working : When Q is low, transistor is cut off and the capacitor charges through R 1 and R 2 . As the capacitor charges, the threshold voltage increases, when it reaches through 2/3 Vcc the upper comparator has a high output and sets of the flip-flop making Q high. This saturates transistor and the capacitor discharges through it. The discharge takes place through resistor R 2 only when the capacitor voltage drops slightly le...

  IC 555 The IC 555 is a more versatile IC, it basically contains built-in timer circuit hence widely known as timer IC. It is introduced by Signetic Corporation in early 1970. IC 555 is basically a monolithic timer circuit which can be used in many applications. It is a low-cost timer capable of producing precise time delays with a wide range. Fig. - Pin diagram  of IC 555 Above fig. shows a pin diagram  of IC 555.  It is an 8 pin IC. Pin 1 is ground , pin 2 is trigger, pin 3 is output, pin 4 reset, pin 5 is control voltage, pin 6 threshold, pin 7 discharge and pin 8 is positive supply voltage. The IC 555 timer will work with any supply voltage between 3 Volt to  18 Volt. (max. load current 200 mA) NOTE : Symbol and Pin Diagram of OPAMP IC 741 NOTE : Working of RSFF   BLOCK DIAGRAM OF IC 555 The IC 555 combines the following elements as shown in the following block diagram. 1. A pot...

  §   Multivibrator •       Multivibrators are a group of circuits which have two states i.e. ON state and OFF state. •       They produce different types of waveforms such as square wave, rectangular wave, pulses etc. •       There are three types of multivibrator: •       1) Astable multivibrator or free running multivibrator •       2) Monostable multivibrator or one shot multivibrator •       3) Bistable multivibrator or flip flop Astable multivibrator or free running multivibrator •       In astable multivibrator, the two states of the circuit are momentarily stable and circuit switches respectively between these two states. •       It does not require any external triggering signal and is self sustaining multivibrator. •       Fo...