For pickup: VAX-11/750 and RK07

Chuck Guzis cclist at
Sat Jun 6 15:32:23 CDT 2009

On 6 Jun 2009 at 20:08, Tony Duell wrote:

> Yes, fuses are very useful for protecting things like transformers and
> wiring harnesses. On the other hand, expensive power semiconductors
> are useful for protecting fuses ;-)

A friend who worked as a DEC field engineer used to talk about DEC 
being notorious for "transistor protected fuses".
> > The charging circuit is pretty crude by modern standards--an LM317K
> > TO3 regulator on a large (4"x6") heatsink with a 50W zener and a 
> What's tyhe 50W zener for, given you have a regualtor chip?

It's on the output side of the LM317, so I imagine it's intended as 
battery protection.

There's also a honking big diode across the output before the 50A 
cartridge fuse in the lead going to the batteries.  I assume it's to 
protect the circuitry in case the batteries are connected with 
reversed polarity.  

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