I just had an idea.
Would it be possible to make a sine wave with the arduino simply be generating a square wave and then putting a capacitor in parallel?
Thanks
~ReCreate
Not with just a single capacitor. However one could implement a low-pass filter (using RC or LC or active filter) designed to pass the fundemental frequency but attenuate the harmonic frequencies. How many component and their values would depend on the quality of distortion in the resulting sine wave you needed.
Lefty
Will be much easier to do with a 555 timer there are many circuits on the net.
Will be much easier to do with a 555 timer
A 555 will only give you a square or a triangle, any generation of a sine wave will have to be done by wave shaping. This is in effect what Lefty suggested. It is as easy to apply this wave shaping to the output of an Arduino as it would be for a 555.
It depends on what you want to do with the sine wave. For example if you want to energise a coil to make an RFID then simply put in a square wave in at the resonant frequency and it turns into a sine wave.