[time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.

[Poul-Henning Kamp]

--------
Hal Murray writes:

> > Very few UPS's are good at long-run applications, they are typically built to
> > run a heavy load for minutes, not a tiny load for hours or even days on end. 
>
> That matches my expectations, but somebody might expect their telco gear to 
> stay up longer than the few minutes it takes to cleanly shut down a computer.

Real Telco gear runs from -48VDC fed from, literally, tons of lead-acid batteries.

Google "telco battery room" pictures if you dont belive me.

Incidentally, the best batteries for this kind of application are literally
called "circular telco batteries", and almost all of them are still in use,
some of them pushing 50 years now:

	https://archive.org/details/bstj49-7-1253/page/n23/mode/2up

> Does all telco gear that is expected to run off UPS take 48V?

In the sense that telcos rarely buy anything but -48VDC kit:  Yes.

> Is there a market in small 48V supplies with UPS option for the telco market?  
> You would have to build a 48V to 24V converter rather than the whole thing.  
> You can probably get a brick for that.

All of 12, 24 and 48VDC are commonly used, and IMO most timing kit is 24VDC.

24VDC is also popular in industrial control settings, for instance:

	https://www.pulspower.com/products/supplementary-units/dc-ups-and-buffer-modules/

It's expensive and good, but these days almost all of it is switch-mode.

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