high freq vco

[patchell]

WeAreAs1 at aol.com wrote:

> In a message dated 8/11/00 9:20:29 PM Pacific Daylight Time,
> diode at hotmail.com writes:
>
> << The 4046 pll chip has a vco that goes to 1MHz, HC4046 maybe even higher..
>  dont worry abt the phase lock bit, just use the vco. makes a sq wave perfect
>  for dividing. >>
>
> Yes, but they are linear VCO's, and have a fairly limited sweep range.  Has
> anyone sucessfully made a reliable expo converter for them, so they can be
> driven by 1v/octave CV?
>

    The 4046, no, that is strictly a Voltage Controlled Oscilator in the true
sense of the word.  The 2207 is actually a current controlled oscilator.  It will
sweep many decades.  I think one of the ones I did would go from about 10Hz up to
about 1MHz (I am not sure what the bottom end was, but the top end was about
1MHz).  You can use your favorite NPN based exponential converter to control it.
At that time, I just used a good old CA3046.  However, as I detailed in my
previous message, the 2207 itself seems to have some irregularities in it's
tuning response.  I was never able to use it for a pitch source.  Even in it's
spec sheet the linearity was speced in the 1 -> 2% range, if I remember.

>
> Michael bacich

--
 -Jim
------------------------------------------------
* Visit:http://www.silcom.com/~patchell/
*-----------------------------------------------
*If you didn't buy a home in Santa Barbara,
* You didn't pay enough!
------------------------------------------------