555 Timer 50% Duty Cycle Astable Multivibrator (Single Timing Resistor to Output)

This is a 50% Duty Cycle Astable Multivibrator using the 555 timer IC. An approximately 50% duty cycle is achieved by using a single timing resistor to output. In contrast to the conventional 555 astable circuit which uses a discharge resistor to the discharge pin and additional resistor to Vcc for charging, this circuit has almost symmetrical charge and discharge periods. A strong pull-up resistor at the output aids in current sourcing to the timing circuit, this helps the output balance its sourcing and sinking capability. The discharge pin is pulled-up to Vcc and is available as an auxiliary output.