[sdiy] square2sine/continuos

[Scott Gravenhorst]

A filter will do the waveshaping job, but the amplitude will
not be constant with respect to frequency.  It can be made
fairly constant if the 555 is operated as a VCO and the filter
is a VCF and the two circuits track.  But now the parts count
goes up.

It is much easier to make a square wave from a sine.  A 555 
can be made to do sawtooth, square and pulse without much trouble, 
and if you look at the capacitor voltage while it is running as a 
square wave oscillator (square out on pin 3) the cap waveform
will be sort of triangular, the ramps will be curved.  The caveat 
of *very* few components tends to be problematic.

Maybe we could be more helpful if you said what this is to be
used for ??

Ragozzino Pasquale <ragozzino at pentium.isu.polimi.it> wrote:
>i need to convert a 555 squarewave to sinewave, but since someone told me
>it is very hard, and i need to do it with *very* few components, i will be
>happy with any continous waveform (triangle would be great). i know i
>could use a filter to make a sinewave but in my circuit the 555 frequency
>is variable. thanks.

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