[time-nuts] float chargers for oscillator backup power

Poul-Henning Kamp phk at phk.freebsd.dk
Mon Oct 27 03:32:57 EDT 2014


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In message <6C69ADEB-A4D8-4DEE-A5D4-AEC0FD16490A at n1k.org>, Bob Camp writes:
>HI
>
>We seem to have drifted a bit.
>
>This started out as a supply for the Z3xxx Lucent GPSDO’s. [...]

Which, being telco material, is likely built to work exactly the way
I described:  An unclean, unregulated DC bus, and an internal DC/DC
converter to clean it up and isolate it.

I thought we were talking 'naked' OCXOs.

One interesting setup I've seen, and which I'm contemplating next
time I renovate my DC supply is this:

* 30V power supply powers DC bus through diode.

* Battery, also diode to DC bus

* Bulk charger for filling up battery after discharge, turns once
  current decreases to setpoint.

* Per battery DC/DC converters from the DC bus does float-charge.

The two main points to this is that you can use a heavy duty
bulkcharger, without paying for its losses in float-mode, and that
each battery (if you have more than one) gets optimal float-charge
regulation.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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