[sdiy] Hi frequency VC clock

[Tom Wiltshire]

On 20 Jun 2017, at 23:09, Neil Johnson <neil.johnson71 at gmail.com> wrote:

> Hi,
> 
> mark verbos wrote:
>> 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…
> 
> Which manufacturer are you using?

Unfortunately this is an extremely pertinent question. When I looked into something similar, I bought three or four different types because I'd heard they were different and so it proved. Different to the extent that I couldn't use the same components values with different manufacturer's chips. Each "4046" is essentially its own device, despite having the same part number.

Tom