[sdiy] CMOS chip questions

[Graham Atkins]

I believe using individual regulators on PCB's is a common practice.  
IIRC the
Prophet 5 has individual regulators per board.

Tom, could not make it to Cambridge this year, hope there are lots of  
nice pics
to post.....looking forward to this.

Graham

On 19 Jul 2009, at 14:14, Tom Wiltshire wrote:

>
> On 18 Jul 2009, at 16:43, David G. Dixon wrote:
>
>>> well i meant in a situation where you are trying to replace 74 TTL  
>>> with a
>>> higher voltage CMOS compatible TTL.
>>>
>>> i suppose i should just learn to design with actual 5 volt 74LS
>>
>> I think the most convenient way to go when mixing digital and  
>> analog is
>> simply to add a 5V supply to the board for digital IC's with  
>> 78L05.  Then
>> you can use whatever digital IC's are best for a given application,  
>> and you
>> don't need a stand-alone 5V supply.
>>
>> Of course, the gurus may beg to differ.  I'd be interested in  
>> hearing the
>> arguments against this notion.
>
> I'm not claiming "Guru" status just yet either, but that's what I'd  
> do. If you've got a lot of logic or digital stuff, then add a +5V to  
> your power supply. Otherwise, just stick a regulator on the board  
> that needs it. It works fine.
> I suppose you could make a case that individual +5V regulators on  
> each circuit board (rather than one global +5V supply) might help  
> isolate any digital noise (since digital supplies are not shared).  
> Still, I've done it both ways in the past and not seen much  
> difference.
>
> For what it's worth, Bruce Duncan uses individual +5V regulators  
> with his digital Modcan modules. He might qualify for "Guru" status!
> (Care to chip in, Bruce?)
>
> HTH,
> Tom
>
> (Just come back from SDIY UK in Cambridge)
>
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