[time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board
bruce.griffiths at xtra.co.nz
Wed Oct 31 16:54:32 EDT 2007
xaos at darksmile.net wrote:
> 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
> 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.
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.
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