[XCSSA] Power Supplies Continued

[X-otic Computer Systems of San Antonio]

Hmmm...I was actually sort of thinking something similar. Now this one  
has a center tap, but would the same thing work if I had a standard  
multi-tap (1 primary, 2 secondary)? Either way, how exactly does one  
hook this up to do that? I've read that you can double the voltage if  
you hook it up a certain way, but I thought it was one or the other?  
In other words, I couldn't tap off one secondary (say to get 5V) and  
both secondaries (to get 10V) at the same time? I'm not sure if my  
explanation is even correct but hopefully it's enough? :) I'm trying  
to find the data sheet I saw the different hookups on still but, of  
course, I can't find it when I need it :P

Sounds like this might work out well though! The only thing I'd need  
to work out would be how much DC voltage I'll end up with in various  
configurations. The specs on the 78xx call for providing 1-2V above  
what it is going to regulate, but I'm not sure how that translates  
with AC. I know that AC output depends on load, etc. but I've never  
gotten a clear explanation of what type of AC adapter to use in order  
to properly regulate the result?

Thanks again!

On Dec 27, 2008, at 6:53 PM, X-otic Computer Systems of San Antonio  
wrote:

> Tim,
>
> What about something like this,
> http://www.mouser.com/Search/Refine.aspx?Keyword=546-187E10
> The secondary is 10VAC with a Center Tap.
> That should give you 10 and 5 VAC...
>
> /Fredrik
>
> X-otic Computer Systems of San Antonio wrote:
>> If I could find a clean one, that might work. Trouble is, most
>> switched power supplies are quite noisy for analog audio  
>> applications.
>> The SIDs are analog devices and so require very clean power. To be
>> fair, I've used some nasty DC power supplies and things worked out -
>> the smoothing capacitors did their job, but I think converting AC to
>> DC oneself tends to be the better route to go. That way you know how
>> it's made, etc.
>>
>> That's one reason I'm trying to avoid using multiple voltage
>> regulators in fact. Supposedly, chaining regulators adds noise as
>> well, so if I can use a single regulator for each output that might
>> result in a nicely quiet solution. I think I may end up going with  
>> two
>> transformers ultimately. Finding a multi-tap that can output  
>> something
>> close to 5 and 9VAC seems to be somewhat difficult.
>>
>> Decisions decisions! :)
>>
>>
>> On Dec 27, 2008, at 5:41 PM, X-otic Computer Systems of San Antonio
>> wrote:
>>
>>
>>> Perhaps you might consider using two modular DC switching supplies
>>> (5V/1A & 9V/300mA) that have regulators and over-voltage protection
>>> built-in?
>>>
>>> You could mount the two supplies in a hobbist handy box, and add
>>> an on/off switch and input fuse for the 120VAC line.
>>>
>>> Lou
>>>
>>>
>>>
>>>
>>>
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>>
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