Astable Multivibrators

Astable Multivibrators

-have no stable state.

-these circuits are more commonly known as oscillators.

     

A typical astable multivibrator or oscillator may be formed using CMOS gates.

                       

The 555 Timer

               -is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. 

Pin Names

                                 

Astable Operation

  

Charge period t1 = 0.693(R1+R2) C

Discharge period t2 = 0.693(R2) C

Total period T = t1+t2 = 0.693(R1+R2) C

The operating frequency of the generated square wave is equal to 1/T or in simplified form,

f =       1.44         

     (R1 + 2R2)C

The duty cycle is a factor of the resistors,

D =         R2         

        R1 + 2R2

Reference:

          Benjo Tirol. Fundamentals of Digital Electronics. Electronics Hobbyists Publishing House. 

    https://www.google.com.ph/searchq=astable+output&biw=1366&bih=677&source=lnms&tbm=isch&sa=X&ei=BKcPVIyrIdagugS9oDIDA&sqi=2&ved=0CAYQ_AUoAQ#facrc=_&imgdii=_&imgrc=Xcfz1bfXsmOqpM%253A%3BJk1HC25GWAlWCM%3Bhttp%253A%252F%252Fwww.electronicstutorials.ws%252Fsequential%252Fseq11.gif%3Bhttp%253A%252F%252Fwww.electronics-tutorials.ws%252Fsequential%252Fseq_3.html%3B392%3B169

https://www.google.com.ph/searchq=astable+output&biw=1366&bih=677&source=lnms&tbm=isch&sa=X&ei=BKcPVIyrIdagugS9oDIDA&sqi=2&ved=0CAYQ_AUoAQ#tbm=isch&q=cmos+gate+of+astable&facrc=_&imgdii=_&imgrc=FGIPeRTnnU2TsM%253A%3Bl0u09NI7ybo5PM%3Bhttps%253A%252F%252Fwww.calvin.edu%252F~pribeiro%252Fcourses%252Fengr332%252FHandouts%252FChap13_files%252Fslide0022_image066.jpg%3Bhttps%253A%252F%252Fwww.calvin.edu%252F~pribeiro%252Fcourses%252Fengr332%252FHandouts%252FChap13_files%252Fslide0022.htm%3B258%3B104

https://www.google.com.ph/searchq=astable+output&biw=1366&bih=677&source=lnms&tbm=isch&sa=X&ei=BKcPVIyrIdagugS9oDIDA&sqi=2&ved=0CAYQ_AUoAQ#tbm=isch&q=555+timer+png&facrc=_&imgdii=_&imgrc=yqTm6CtckSCXMM%253A%3B7ugZdBO-hB5hPM%3Bhttp%253A%252F%252Fupload.wikimedia.org%252Fwikipedia%252Fcommons%252Fthumb%252Fc%252Fc7%252F555_Pinout.svg%252F500px-555_Pinout.svg.png%3Bhttp%253A%252F%252Fwww.newprojectwala.com%252F2013%252F02%252F555-timer-ic.html%3B500%3B330

https://www.google.com.ph/searchq=astable+output&biw=1366&bih=677&source=lnms&tbm=isch&sa=X&ei=BKcPVIyrIdagugS9oDIDA&sqi=2&ved=0CAYQ_AUoAQ#tbm=isch&q=astable+multivibrator&facrc=_&imgdii=_&imgrc=RBgNuB69QvoU5M%253A%3Bk__NDhDuWBcXCM%3Bhttp%253A%252F%252Fwww.yashplus.com%252Fwpcontent%252Fuploads%252F2014%252F01%252Fimage4.png%3Bhttp%253A%252F%252Fwww.yashplus.com%252F2014%252F01%252Fic-555-as-astable-multivibrator%252F%3B761%3B298