[nrv-hams] Sine Wave Morse Code Oscillator Circuit Needed

[Alvin P. Schmitt]

I am using ltspice  using an op amp with input cap of 100uf and
resistor (feedback) 15k. will let you know I have to fig out how to
make it a 741.

On Thu, Jul 11, 2024 at 9:22 AM Cam Coble <cam at doubleclickdata.com> wrote:
>
> I am using an RC low-pass filter with 4 stages at this point already to try
> to smooth a square wave. It's just not looking good on the scope.
> Values are 1.5k resistors in series with caps of 0.01 uF to ground.
>
> --
> Cam, W4XXV
>
> On Thu, Jul 11, 2024 at 8:45 AM Alvin P. Schmitt <schmitt.alvin at gmail.com>
> wrote:
>
> >
> > https://www.google.com/search?q=how+do+you+get+a+sine+wave+from+a+square+wave+circuit&sca_esv=554492d1fd62c51c&sxsrf=ADLYWIJqd2SaJGzaOZrPEQi32KDfCfsTqA%3A1720701822058&source=hp&ei=ftOPZo_FAZmu5NoPwbW6uAc&iflsig=AL9hbdgAAAAAZo_hjjYx0hYsYOqP7lCWqGu9tj_czDU0&ved=0ahUKEwiP_PbmgZ-HAxUZF1kFHcGaDncQ4dUDCBc&uact=5&oq=how+do+you+get+a+sine+wave+from+a+square+wave+circuit&gs_lp=Egdnd3Mtd2l6IjVob3cgZG8geW91IGdldCBhIHNpbmUgd2F2ZSBmcm9tIGEgc3F1YXJlIHdhdmUgY2lyY3VpdDIFECEYoAEyBRAhGKABMgUQIRigATIFECEYoAEyBRAhGKABMgUQIRirAkiSBlAAWABwAHgAkAEAmAFkoAFkqgEDMC4xuAEDyAEA-AEC-AEBmAIBoAJrmAMAkgcDMC4xoAfWCA&sclient=gws-wiz
> >
> > On Thu, Jul 11, 2024 at 8:25 AM Cam Coble <cam at doubleclickdata.com> wrote:
> > >
> > > Not as easy as I thought...
> > >
> > > OK, there are *plenty* of circuits out there making use of 555 timers and
> > > other methods that create square waves, and I can certainly filter the
> > > output to make it sound a little better, but I'm reaching out to find if
> > > anyone has a link or schematic for a nice sine wave oscillator for CW
> > > practice.
> > >
> > > If there is a good kit, send that link too, but I prefer to scratch
> > build.
> > > This may be something we use for a Winter Build Project if I get the
> > time.
> > >
> > > My last attempt was using a side-tone generator from the W1FB's QRP
> > > Notebook (pp145 lower left circuit) along with an LC filter. I evidently
> > > need practice with my filters as It looks like I only got the start of
> > the
> > > square wave smoothed out. This helps, but there's nothing like the sound
> > of
> > > a real sine wave.
> > >
> > > Target is 700 Hz (or variable), and at least headphone output levels.
> > > Bonus for some debouncing for use with a Bug.
> > >
> > > Help!!!
> > >
> > > 73
> > > --
> > > Cam, W4XXV
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