The presented circuit produces PWM pulses which are perfectly optimized and is quite similar to a sine wave and thus very much becomes an equivalent to a sine waveform counterpart. Basically a couple discrete stages are used here which generate the said pulses, the first stage consisting of the op amp 741 or any other similar IC generates square wave and triangular pulses, which are fed to the IC555 stage for further processing. Let’s learn the whole concept in details.
How the Circuit Functions – The PWM Stage
Please refer the CIRCUIT DIAGRAM
Referring the diagram, the whole concept may be understood as follows:
The two op amps are fundamentally positioned to produce the desired sample wave forms for the IC 555. These outputs from the op amps stage is responsible for the production of square and triangular waves.
The preceding stage which is actually the main part of the design consists of the IC 555. In this stage the IC is configured in a monostable multivibrator (AMV) mode with the square-waves from the op amp stage fed to its trigger pin #2 and the triangular waves injected to its control voltage pin # 5.
The square wave input triggers the monostable and creates a chain of pulses at the output. As a result the triangular signal modulates the sections of the fed square wave pulses.
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