I have 12V@60Hz input square wave and wanted to convert into a sine wave. Can anybody tell me how can I do that? What kind of filter I should use ( Lowpass, bandpass filter)??
Thank you.

 

Well, your fundamental is at 60Hz, then you have harmonics at multiples of 60Hz. When added, you get a square wave. Therefore, you need a low pass filter to get just the fundamental component. Depending on how much distortion you can tolerate in the output wave, you might need a 2nd or higher order filter since 120 and 60 (for example) are close together.

 

it would be alot easier to do with a triangle wave?

If you integrate a square wave you will get a triangle wave. Then filter it, but the harmonics are not just the Odd as in a square, they are the odd^2 thus bigger gaps between harmonic => easier to filter.

Remember to AC couple the output

 

This sounds to me rather like a power conversion (using an inverter), rather than a simple signal - would that be so?.

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Do u guys have any circuit I could use?? Passive or acive?? Thank you

 

That depends on how you are using it. If you just want a low power signal that you can feed to an amplifier or something, then you can search the internet for op-amp low pass filter or RC low pass filter. Again, your application is important. If this is a higher power part of the system, then you will need a similar approach, but the choice of components will be more limited.

 

I built a passive lowpass filter a resistor series with a capacitor, but it give me like a triangle wave, so then I built a bandpass filter using a resistor in series with a capacitor parallal with a inductor, but still give me a triangle wave.