How to use 555 Timer to make a 50% Duty Cycle Astable Oscillator

This is a quick summary of how to use 555 Timer to make a 50% Duty Cycle Astable Oscillator.

50% Duty Cycle Astable Oscillator

The above 555 oscillator produces a 50% duty cycle as the timing capacitor, C1 is charging and discharging through the same resistor, R2. When the output from the 555 oscillator is HIGH, the capacitor charges up through R2 and when the output is LOW, it discharges through R2. Resistor R1 is used to ensure that the capacitor charges up fully to the same value as the supply voltage.

The formula for calculating the output frequency at pin 3 is as follow.

Below is the frequency range of the above design using the above formula.

The waveform of pin 3 when R2 is around 96K Ohm. It's about 0.5Hz.

References:

555 Oscillator Tutorial <-- Very Good!!
http://www.electronics-tutorials.ws/waveforms/555_oscillator.html

Pulse Generator circuits using IC-555
http://www.eleccircuit.com/simple-pulse-generator-circuit-by-ic-555/

Variable frequency generator using a 555 timer chip
http://www.edaboard.com/thread262276.html

Unit Converter

Farad ↔ Microfarad Conversion
http://www.endmemo.com/sconvert/fuf.php

Unit Juggler
https://www.unitjuggler.com/convert-frequency-from-s(p)-to-Hz.html?val=1.6