555 timer IC audio amplifier circuit schematics

Posted on Feb 6, 2014

Here we are going to discuss about a simple timer IC 555 project. The 555 timer IC can be used as an audio amplifierwithastable multivibrator configuration. It functions as to carry outpulse width modulation (PWM) of audio signal. Current(I) capacity of 555 timer amplifier is 200mA which is sufficient to drive a small speaker. This simple 555 IC ba

555 timer IC audio amplifier circuit schematics
Click here to download the full size of the above Circuit.

sed amplifier circuit is a good substitute for conventional low power amplifiers. The low frequency audio signal is applied to the control voltage pin (5th pin) of 555 for pulse width modulation (PWM) generation. For beginners who want to know what is PWM `, read simple PWM modulation concept. In the normal mode, we just open circuit the 5th pin (Control voltage pin) of 555 IC. But the most interesting fact we often neglect is that if a low frequency signal is applied to the 5th pin of 555 IC, pulse width modulation starts. Here the oscillating frequency of 555 astable is approximately 145 KHz. The discharge time of capacitor C3 via diode 1N4007 is too fast since there is no resistor to discharge. The process of pulse width modulation starts and as we know the speaker does not respond to this much high frequency, it responses to the usual DC value of the modulated output. Hence the audio signal gets amplified.

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