[sdiy] 4046 VCO

[KD KD]

Howdy!

The CD4046 is quite different the HC variants and not interchangeable for any
given circuitry, depending on design you need to change the charge cap on
HC4046 and/or adjust Iref and/or the V low Hz trim in your expoconv depending
on charge cap value. HC4046 is a 20-30Mhz device while the CD4046 maxes
out abut 3-4Mhz or so depending on manufacturer.

Regards.

2018-07-06 1:20 GMT+02:00, Tim Ressel <timr at circuitabbey.com>:
> Hiya,
>
> So I built up a Thomas Henry 4046 VCO and ran into an issue: the
> frequency out is way too high, starting at 55KHz and going up to 175KHz.
> I checked my schematic and it all looks good except for one thing; I am
> using a 74HC4046 instead of a CD4046. Is that causing my problem?
>
> --
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
>
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