[sdiy] How To Make This Oscillator into a VCO

[Scott Gravenhorst]

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?


>> 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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