[sdiy] Hi frequency VC clock

[Jay Schwichtenberg]

Think that we need to pay attention to the fact that this is a 74HC4046 and not a CD4046. From looking at the data sheet they are different chips with different characteristics.


Some where and I can't remember where I remember reading something about this for the CD4046 and you should give it a small bias for the frequency or things can get weird.


Jay S.

> 
>     On June 20, 2017 at 5:21 PM Tim Ressel <timr at circuitabbey.com> wrote:
> 
>     Hi,
> 
>     According the TI spec sheet the range for the VCOin pin is 1.1 volts to
>     about 4 volts depending on the supply.
> 
>     The Thomas Henry 4046 VCO design (X-4046) ran a current source from an
>     expo converter into pin 11 (R1) and tied the VCOin pin to +V. You might
>     try that.
> 
>     --timbo
> 
>     On 6/20/2017 1:09 PM, mark verbos wrote:
> 
>         > > 
> >         hi all,
> > 
> >         I’m making a new digital delay using some adaptive Delta type 1 bit techniques. I’d like a clock that can be swept from 250kHz to 3MHz without any glitches.
> >         I’m using a 74HC4046 and it is almost right, but it freaks out when the CV gets near zero and jumps down to a lower frequency. Is this normal? What am I doing wrong?
> >         I have a 220p cap and a 10k on pin 11 and a 100k on pin 12.
> > 
> >         Thanks for any insights…
> > 
> >         Mark
> > 
> >         _______________________________________________
> >         Synth-diy mailing list
> >         Synth-diy at synth-diy.org
> >         http://synth-diy.org/mailman/listinfo/synth-diy
> > 
> >     > 
>     --
>     --Tim Ressel
>     Circuit Abbey
>     timr at circuitabbey.com
> 
>     _______________________________________________
>     Synth-diy mailing list
>     Synth-diy at synth-diy.org
>     http://synth-diy.org/mailman/listinfo/synth-diy
> 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20170620/9646f90a/attachment.htm>