Astable Multivibrator Using 555

Design of Square wave of frequency 1 kHz with duty cycle 75% T = 1/f = 1ms Ton = 0.75 ms Toff = 0.25 ms Toff = 0.693*RB*C Let C = 0.1 microFarad, Then RB = 3607.5 Ohm = 3.61 kOhm Ton = 0.693*(RA + RB)*C Then RA = 7215.01 Ohm = 7.215 kOhm