[sdiy] Power distribution board

[Scott Nordlund]

The 74xx parts are generally 5V only.  4000 series parts are fine, but if there's analog stuff in the vicinity, you may want to isolate them (with a choke followed by a capacitor, maybe) to ensure that their switching transients won't interfere with the rest of the circuit.  Note also that 74xx logic levels are fixed (though not always directly compatible between sub-families) while 4000 series logic levels depend on the power supply voltage.

Also it should be said that if you're considering a switching regulator, many of those have minimum load requirements.  In some cases, operating them without a load connected can destroy the circuit.

Or 74HC chips would probably reduce power consumption to the point that a 7805 is fine.

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> Date: Sat, 4 Apr 2009 13:32:09 -0700
> From: dixon at interchange.ubc.ca
> Subject: RE: [sdiy] Power distribution board
> To: gsn10 at hotmail.com; synth-diy at dropmix.xs4all.nl
>
> As most (all?) CMOS chips can be powered from +15V, 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.
>

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