[sdiy] How To Make This Oscillator into a VCO

[patchell]

Scott Gravenhorst wrote:

> patchell <patchell at silcom.com> wrote:
> >
> >
> >Scott Gravenhorst wrote:
> >
> >> patchell <patchell at silcom.com> wrote:
> >> >    I was wrong, this circuit will work with any opamp.  If you look in your 1982
> >> >National Semiconductor Linear Data Book on page 3-32 ( LF356) you will find a
> >> >similar VCO.
> >> >
> >> >patchell wrote:
> >> >
> >> >>     I would have to look at the circuit again...but I think that the common
> >> >> mode input range needs to include the negative voltage terminal on the opamp.
> >> >> This is strictly a single supply type application, although, I could be wrong.
> >> >>
> >> >>     One big disadvantage of this circuit is that it is stricktly linear
> >> >> response.
> >>
> >> Tack on your favorite expo converter to get expo response.
> >>
> >> Is it not true that most/all VCOs have a linear CCO core anyway?
> >
> >    In general, that is true...but in this case, this is a true Voltage Controlled
> >oscilator.  This one you cannot control with a current source.
>
> Ok, on second look I think I see that.  The data sheet doesn't give any idea of how
> linear it is.  Any guesses?

    Don't know for sure...the circuit (basically the same circuit) that is shown for the
LF356 says 0.1%....not great, but not bad either.

>
>
> >>
> >>
> >> >> Gavin wrote:
> >> >>
> >> >> > Wow! nice circuit, now ill this work with other op amps?  or is it specific
> >> >> > to the properties of the lm324?
> >> >> > ----------
> >> >> > >From: patchell <patchell at silcom.com>
> >> >> > >To: bill berzinskas <housenationmedia at yahoo.com>
> >> >> > >Cc: synth-diy at dropmix.xs4all.nl
> >> >> > >Subject: Re: [sdiy] How To Make This Oscillator into a VCO
> >> >> > >Date: Sat, Oct 19, 2002, 4:46 PM
> >> >> > >
> >> >> >
> >> >> > >    Yes it can...look in a National Semiconductor data sheet for the
> >> >> > >LM324.  There is a VCO that will produce a triangle that uses no OTAs.
> >> >> > >In fact, this is what I built for my first synthesizer back in 1974.
> >> >> > >Worked a lot better than the Paia 2720 oscilator...in some ways.
> >> >> > >
> >> >> > >bill berzinskas wrote:
> >> >> > >
> >> >> > >>    Thanks for all the good responses..  tons of good info..
> >> >> > >>
> >> >> > >>
> >> >> > >>
> >> >> > >> Next Question:   Can this be done without an OTA?  For the most part,
> >> >> > >> i'm working with standard opamp pieces..
> >> >> > >>
> >> >> > >>
> >> >> > >
> >> >> > >--
> >> >> > > -Jim
> >> >> > >------------------------------------------------
> >> >> > >* Visit:http://www.silcom.com/~patchell/
> >> >> > >*-----------------------------------------------
> >> >> > >*I'm sure glad Merry Christmas comes just once a year
> >> >> > >* -Yogi Yorgensen
> >> >> > >------------------------------------------------
> >> >> > >
> >> >> > >
> >> >>
> >> >> --
> >> >>  -Jim
> >> >> ------------------------------------------------
> >> >> * Visit:http://www.silcom.com/~patchell/
> >> >> *-----------------------------------------------
> >> >> *I'm sure glad Merry Christmas comes just once a year
> >> >> * -Yogi Yorgensen
> >> >> ------------------------------------------------
> >> >
> >> >--
> >> > -Jim
> >> >------------------------------------------------
> >> >* Visit:http://www.silcom.com/~patchell/
> >> >*-----------------------------------------------
> >> >*I'm sure glad Merry Christmas comes just once a year
> >> >* -Yogi Yorgensen
> >> >------------------------------------------------
> >> >
> >> >
> >>
> >> =========================================================
> >> - What good are laws that only lawyers understand?
> >> - Government: The other religion.
> >> - The media's credibility should always be questioned.
> >> - Lambs who lie down with lions are lunch.
> >>
> >> -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
> >> -- Linux Rex         | RedWebMail by RedStarWare
> >> -- FatMan: home1.GTE.NET/res0658s/FatMan/
> >> -- NonFatMan: home1.GTE.NET/res0658s/electronics/
> >
> >--
> > -Jim
> >------------------------------------------------
> >* Visit:http://www.silcom.com/~patchell/
> >*-----------------------------------------------
> >*I'm sure glad Merry Christmas comes just once a year
> >* -Yogi Yorgensen
> >------------------------------------------------
> >
> >
>
> =========================================================
> - What good are laws that only lawyers understand?
> - Government: The other religion.
> - The media's credibility should always be questioned.
> - Lambs who lie down with lions are lunch.
>
> -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
> -- Linux Rex         | RedWebMail by RedStarWare
> -- FatMan: home1.GTE.NET/res0658s/FatMan/
> -- NonFatMan: home1.GTE.NET/res0658s/electronics/

--
 -Jim
------------------------------------------------
* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
------------------------------------------------