square to sine

if sinesness isn't VERY important, why not use a capacitor.

Not 1Khz but might be useful You could modify this circuit This fits the bill exactly All from google..

Tim

To get a nice sine wave you need a band pass filter centered at 1kHz.

-howy

"howy" wrote in news:1131129826.287809.41610 @z14g2000cwz.googlegroups.com:

How big of a notch can you set before the sine wave degrades/deteriorates?

Joe

Why do you want a sine wave? And at what power level? Are you having motor problems because you're driving a motor with a square wave? Or something else?

John Nagle

How long is a string? (How much distortion can you tolerate?)

A square wave is the sum of the odd harmonics: v(?) = sin(?) + sin(3?)/3 + sin(5?)/5 +...

?, omega, is 2pf.

"Mike Young" wrote in news:IsWaf.12920$ snipped-for-privacy@newssvr27.news.prodigy.net:

Thank you

Hi John, I want to drive a coil using a sine wave.I used to use a 5th order filter from Maxim for the conversion of square wave(1khz which is generated by the PIC micro) to sine wave.But that filter works fine but it also needs 125khz (square wave) to convert 1khz square wave into

1KHZ sine wave.So i used to generate 1KHZ and 125khz square wave from the pic and then feed these waves into the filter and then the output from the filter will be a pure 1KHZ sine wave which is then used to drive the coil in one of my applications.But now the problem is that this takes too much of the processor power .So i am looking for a an alternative solution or a circuit where i can feed my reference signal from the PIC(which is 1KHZ square wave) which theron converts the 1khz square wave into 1khz sine wave. Regards Sandeep

What part number from Maxim?

What PIC are you using and how are you generating these signals? This should be very easy to do without maxing out the PIC. Depending upon the PIC, you should be able to generate at least one of these signals without using any software at all (see Capture/Compare feature in datasheet, you want to do a Compare). The 1kHz signal could be generated with a timer based interrupt and should consume allot less than 10% of the available CPU (assuming a 4MHz clock).

How much distortion is allowable?

I'm still not clear on what you're trying to do. But I'd start by making a low-pass R/C filter (one resistor, one capacitor) with a cutoff somewhere around 1 KHz.

Here's a calculator for R/C filters:

John Nagle