[sdiy] Power distribution board

[Roy J. Tellason]

On Saturday 04 April 2009 04:32:09 pm David G. Dixon wrote:
> As most (all?) CMOS chips can be powered from +15V, 

The 4000 series parts,  yeah,  but not the 74(H)C series,  which have a much 
lower voltage rating...

> then this eliminates the need for a 5V supply.  However, it also makes a
> good argument for the separate ground line on the 4-pin MTA connector, does
> it not? 
>
> > If you want to reduce power consumption, use CMOS chips.  The plain 74xx
> > chips consume a lot of power.  74LS or 74ALS are better, but I believe
> > the the HC/HCT/AC/ACT series (and also 40xx series) are most efficient.

I like to have a 5V supply for things like LEDs so I can avoid wasting more 
power in the resistors associated with those,  and to keep that current 
switching on and off out of the power circuits carrying audio.  One little 
box I built a bunch of years ago had a "mute" button and an associated LED 
and you'd get a distinct click in the audio every time you toggled it on or 
off.  :-(



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