[sdiy] How To Make This Oscillator into a VCO

[patchell]

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.

>
>
> >> 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
> >------------------------------------------------
> >
> >
>
> =========================================================
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>
> -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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--
 -Jim
------------------------------------------------
* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
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