[sdiy] How To Make This Oscillator into a VCO

[Scott Gravenhorst]

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?

>>
>>
>> >> 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/