Re: Power Supplies, Saving Money, and switching vs. Linear?

[Frank Olson <Use_the_email_links@xxxxxxxxxxxxxxxxxxxxxx>]

Andrew(N) wrote:
> My electronics/wiring closet is costing $56/month to run. Ouch. Too
> much! So one-by-one I am changing things to be more power-conscious.
>
> Starting with a big linear 12V power supply. Altronics 12V, 4A type
> linear power supply with battery backup: standard for alarms (a few
> years back). I currently draw about 500 ma continuously, (Not sure what
> my peaks are, but bells and sirens are powered separately.
>
> This draws around 1.1 A on the AC line, so 132 Watts continuously. Big
> transformer, always warm. Seems wasteful.
>
> IF I SWITCH TO A NEWER, SWITCHING POWER SUPPLY, say the Elk P412 (or
> any other you recommend) WOULD I DRAW MEASURABLY LESS AC CURRENT?
>
> I am powering various motion detectors,  InfraRed repeaters (Niles), a
> small, 7 Watt audio amplifier and a few other devices.  Would the 100
> MV ripple on the Elk power supply bring any problematic noise along
> with it?
>
> Thanks for your suggestions
>
> -Andrew


You may save a little going with a more efficient power supply, but it
won't be significant because you aren't making any changes to the field
devices that draw the bulk of your power.  Reducing the size of the
transformer won't affect things much either (the smaller one will tend
to run even hotter).  Where the "savings" will come in is the
efficiencies gained in the charging circuit for the stand-by battery,
but that's about all I see as any real benefit.

In the future I would suggest posting a question like this in each group
individually (and avoid cross-posting).  That way if the thread
"disintegrates into flame wars" in one group it won't affect the other.

Frank Olson
http://www.yoursecuritysource.com
(cross posted between ASA and CHA)