[XCSSA] Power Supplies Continued

[X-otic Computer Systems of San Antonio]

On Dec 29, 2008, at 3:42 PM, X-otic Computer Systems of San Antonio  
wrote:

> On Sunday 28 December 2008 07:05:59 am X-otic Computer Systems of  
> San Antonio
> wrote:
> [...]
>> I'd fuse the Vcc inputs right where they enter your printed circuit  
>> board.
>
> Hey Tim..
> I would make the AC fuse case mounted.. and the DC fuse(s) PCB  
> mounted just
> before the regulator (or after the rectifier).  You might also want  
> to mount
> those sacrificial MOVs that I told you about betwen the three AC  
> legs (before
> the transformer) too, in case you experience a power surge.

Case mounted? What does that look like? :) Do you mean having screw in  
fuse holders that I can remove the fuses without needing to open up my  
box? I was thinking of just having a small "fuse board" that just has  
fuses on it for everything and wiring that up before or after my  
regulating board. I was going to screw the transformer to the case  
though. It'd cost way to much to try and fit that thing on my  
regulating board (and I can't find a center-tapped transformer in the  
default Eagle library). MOVs are a good addition indeed. I was  
planning on adding those in my final design - after I figured the rest  
of this all out :) Now you said between the 3 AC legs? I assume you  
meed +, neutral and GND? If so, I wasn't sure how to hook up GND? Is  
that to the chassis or?

Finally, quick question that I wasn't able to find online? :) Is there  
a proper order to capacitors? I've been going big to small (so Rectify  
-> 2200uF -> 47uF -> 330nF -> Regulator -> ...) but the problem is  
that I'm running out of room on my board. In order to keep the size  
down, I was going to switch around a few of those (say 47uF and 330nF)  
but I didn't know if that would still filter out HF noise properly,  
etc. I was also curious - the auto-router in Eagle doesn't actually  
route the capacitors on the same trace. It say goes from the rectifier  
and then has 2 lines, one that goes to the 2200uF and my regulator,  
and another that goes to the 47uF and 330nF caps. Would that actually  
work? Or, perhaps more succinctly, can I hook capacitors up in a star  
like that and still get the same filtering affect? I always thought  
they had to be run all on one trace (which means my board has gotten  
quite complex :).

I figured pictures might help, so:

http://www.moocowproductions.org/temp/board-autorouted.png
http://www.moocowproductions.org/temp/board.png
http://www.moocowproductions.org/temp/schematic.png

Granted, I'm not suggesting Eagle is routing correctly (or that I set  
it up right) so I just did that to illustrate the example.

Thanks!

Tim S.

P.S. Hey Fredrick, I dunno if I told you, but I've started working on  
modding out the C64 case :)