[XCSSA] Can you break transformers?

[X-otic Computer Systems of San Antonio]

Heheh that's clever :) Speaking of though (power transformers anyway),  
I thought I would send out my updated power board I'm thinking of  
getting printed. Unfortunately, because this one has fuses, the cost  
has ballooned up to $25 from batchpcb.com :P It's not all that  
complicated so I can make a protoboard, but honestly I'd rather pay  
for a printed one since I thing protoboards look ugly :) and there's  
less change of making a mistake while building the thing.

I hit the max posting size the first time I tried to post this with  
images embedded, so here's links:

http://www.moocowproductions.org/temp/powerboard-alt-schematic.png
http://www.moocowproductions.org/temp/powerboard-alt.png

One question I had, and I wasn't able to get a good answer on the  
MidiBox forums, was if I might be overdoing it on the fuses. I was  
thinking of a 1A fuse for the shared rectified input. But since I am  
offering that also as an output (which can be useful when powering  
boards that already have a voltage regulator on them, such as the 6581  
SID board). So, I also have a 250mA fuse going to that output pin. The  
idea was that, if I shorted something on that output in (say on the  
board it's powering), that fuse would blow. 250mA is also somewhat of  
a wild guess. I think the whole thing fully assembled might consume  
closer to 500mA, but I'm not sure which "rail" will consume the most  
at this point.

I also had some feedback from the MidiBox community on the capacitor  
selection, but I'm not sure if I might be overdoing that (or  
undergoing it for that matter) as well. The goal is to filter as much  
of the noise of the regulators and ripple of the AC as possible. I  
figure caps are cheap so it can't hurt to have too many instead of too  
few *shrug*, but the capacitance values are what is sort of not set in  
stone. I took the .33 and .1 uF caps directly from the C64 power board  
schematic I used to built my first power board, and added the 47uF as  
a suggestion from another MidiBoxer (he suggested between a 10-100uF  
electrolytic cap and 47uF was both cheap and plentiful on Allied  
Electronics).

I might be going overboard on the regulators too, but I did it that  
way since someone pointed out the 7812 could get really hot if I was  
sharing amongst all my outputs. I was going to put heatsinks on all of  
them just in case however (I have some really cool cobalt blue ones  
originally used on a video card cooling kit that will look awesome :)  
but, again, I figured it better to overbuild instead of underbuild the  
thing.

Suggestions welcome :)

Werd,

Tim




On Sep 5, 2008, at 8:55 PM, X-otic Computer Systems of San Antonio  
wrote:

> "Can you break transformers?"
>
> Optimus Prime awaits your challenge. :P
>
> Humor aside, I noticed that a reply I did to one of the "Red Storm  
> Rising" messages is awaiting moderator approval. Huh? All I did was  
> a simple reply. Can somebody check into that?
>
> --Robert Allen Rusk (RARusk)
>
> ____________________________________________________________
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On Sep 5, 2008, at 8:55 PM, X-otic Computer Systems of San Antonio  
wrote:

> "Can you break transformers?"
>
> Optimus Prime awaits your challenge. :P
>
> Humor aside, I noticed that a reply I did to one of the "Red Storm  
> Rising" messages is awaiting moderator approval. Huh? All I did was  
> a simple reply. Can somebody check into that?
>
> --Robert Allen Rusk (RARusk)
>
> ____________________________________________________________
> Boost your productivity with new office software. Click now!
> http://thirdpartyoffers.netzero.net/TGL2231/fc/Ioyw6ijlZW9WKGMsSD7Ey6R9G1EhfRCkymeM26KOBjfQ2THwzypJYW/
>
> _______________________________________________
> XCSSA mailing list
> XCSSA at xcssa.org
> http://xcssa.org/mailman/listinfo/xcssa
>