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To obtain a 50% duty cycle in an astable 555 timer circuit:

tLO = tHI
RA = RB and short RB with a diode during the capacitor charging cycle
capacitor voltage must rise above 1/3 VCC
tLO = tHI, RA = RB, and short RB with a diode during the capacitor charging cycle

Correct Answer: tLO = tHI

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