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Astable Multivibrator with the 555 TimerV CCR AR Bv CCRR2 ⁄ 3 V CCComparator 1+R1 ⁄ 3 V CCS+Comparator 2QQT 1 T 2OutputRFigure 7.10. Astable multivibrator for Example 7.1Solution:The period T = T 1 + T 2(7.6), that is,is a function of the capacitor and resistor values as shown in relationT = T 1 + T 2 = 0.69( R A + 2R B )CThe pulse repetition frequency isf=1⁄Tand thusf = 10 5 = ------------------------------------------1 =0.69( R A + 2R B )C1.443 × 10 8---------------------------R A + 2R BThe duty cycle isT 1⁄ TR A+ 2R B=1.443 × 10 8--------------------------- = 14.43 K Ω10 5and from relations (7.3) and (7.6) we obtain(7.7)T 10.69( RDuty cycle 0.6 ----A + R B )C R------------------------------------------ A + R= = = = ---------------------- B=T 0.69( R A + 2R B )C R A + 2R BR A+ R------------------------ B14.43 KΩR A+ = 0.6 × 14.43 = 8.66 KΩR B(7.8)Subtraction of (7.8) from (7.7) yieldsElectronic Devices and Amplifier Circuits with MATLAB Computing, Second EditionCopyright © Orchard Publications7−7