> To: info-pdp11@village.org
> Subject: Re: UPS devices for PDP11
> From: dworkin@village.org
> Date: Tue, 23 Nov 2004 09:51:41 -0700
> Johnny Billquist wrote:
> : UPS? These old DEC machines have power supplies big enough to act as UPSes
> : themself. Ever looked at those capacitors? :-)
> : [...]
> : You have supplies sturdy enough to smooth out power glitches, and to save
> : themself if you remove power.
> True, but they don't take extended repeated brownouts all that well
> (five or six in a row, each lasting ~30 seconds). At least I've not
> had much luck along those lines.

The way I solved that problem when taking computers to sea on ships
was to build a simple relay circuit that connected to the "emergency
shutoff" on the DEC power controllers, and made any power failure
permanent until a manual reset was performed. So if it goes down,
it stays down until some higher intelligence decides that things
have stabilized again. Not directly suitable for unattended systems.

carl lowenstein marine physical lab u.c. san diego
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