In astable mode, the 555 timer IC operates as an oscillator, generating a continuous square wave output without external triggering. The circuit consists of two external resistors (R1 and R2) and a capacitor (C) connected to the timer.
Here's how it works:
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The external resistors (R1 and R2) and the capacitor (C) determine the timing of the oscillation.
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Initially, the capacitor is charged through R1 and R2 until it reaches 2/3 of the supply voltage, at which point the output of the 555 timer goes high.
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The capacitor then discharges through R2 until it reaches 1/3 of the supply voltage, causing the output to go low.
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The cycle then repeats, creating a continuous square wave output.
The frequency of the output waveform can be calculated using the following formula: f = 1.44 / ((R1 + 2 * R2) * C)
By varying the values of the resistors and the capacitor, you can adjust the frequency of the output waveform generated by the 555 timer in astable mode.
