[time-nuts] yet another GPSDO design, or so

EWKehren at aol.com EWKehren at aol.com
Tue Jun 29 10:20:06 UTC 2010

 just a clarification, I did write 4066 it is a 4046 that I  replaced. Take 
a look at the MCP 4822 dual 12 bit D/A In the data  sheet they have an 
example using one for coarse, the other for fine steps, I  realize that the 
transition is not perfect but maybe code can compensate for the  transition.
 Bert Kehren
In a message dated 6/29/2010 5:10:39 A.M. Eastern Daylight Time,  
attila at kinali.ch writes:


On Sat, 26 Jun 2010 21:14:02 EDT
EWKehren at aol.com  wrote:

> What you want is basically a Shera Board. That design has  been around 
> quite some time and has served me very well.  

Yes. The Shera Board and similar designs serve as an example for  me.

> I have a total of six running  
> including two  controlling Rubidium. There are in my opinion a couple of  
>  problems: not every 4066 works on the design the 18 bit D/A is very hard 
> find  and now expensive and the single step of the D/A is  intended for a 
> E-13  frequency step. 

Yes. My goal is  to update the venerable 4066 with something more
modern and have components  that are easy to get trough farnell, digikey,
mouser, and all the other  distributors. Yes, 16bit D/A seems to
be the maximum that is currently  available. It crossed my mind
to build a 24bit R-2R D/A using discrete  components, but this might
have actually a worse performance than a off the  shelf 16bit D/A.
(temperature drifft, resistor values missmatch, EMI,  etc)

Attila Kinali
If you want to walk fast, walk alone.
If you want to walk far, walk  together.
-- African  proverb

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