[time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Oct 31 16:54:32 EDT 2007

xaos at darksmile.net wrote:
> Said,
> In this particular case, I would solder a "single header pin", to each  
> hole in the OCXO footprint, and then use a "single wire header  
> connector" to attach to it.
> Then, have all 4 wires connect to the interface board via a 4 pin, connector.
> This way, the Fury gets soldered only once and can be disconnected anytime.
> I will add that to the schematic.
> Bruce Griffiths, has been providing me with some excellent feedback on  
> the EFC interface design. I am making a few changes based on his  
> recommendations.
> The more I think about it, the more I am worried about ground  
> isolation between the HP OCXO and the rest of the system.
> I have a few ways to approach this. One is to simply provide 3  
> different voltages to the system, each isolated from each other. In  
> other words, don't use
> voltage regulators to get from +/-24V down to 12.
> The proper solution would be for a separate board which provides 3  
> different DC outputs, all isolated from each other, including ground.
> 1. +24V for the oven. HP OCXO's only.
> 2. +12V For the oven. This could be supplied by the Fury which also  
> compensates for temp.
> 3. +/-12V for the EFC interface.
> The interface board must not add noise to the Fury. Looks like there's  
> more work to be done.
> -G

On board regulators with "remote" sensing can easily accurately regulate
the voltage between the OCXO connector pins and a standard differential
amplifier can be used to eliminate/reduce the effect of any small low
frequency voltage differences between the Fury and the OCXO EFC grounds.
Thus using on board regulators to drop the 24V to a lower voltage for
the OCXO should be OK.


More information about the time-nuts mailing list