[SPARCbook] buzzing noise from ac power supply

[E. Keith Howick, Jr.]

I've used DC-to-AC converters in my car for years with laptops and radios. The
hum exists because the AC-sine wave is artificial, created by a simple series of
square waves. It will stress your power supply. I'd recommend looking for a
better brand of converter. Higher quality converters use more square wave
frequencies and better filtering to smooth the artificial sine wave, that'll get
rid of the hum and stop stressing your power supply.

-Keith

nm wrote:

> I recently bought something called a "power jump".  This is
> a little box that plugs into a car's cigarette lighter and has
> has one 110v AC outlet on it (like in a house).  Anyway I can
> plug the ac power supply that came with my sparcbook 3gs into
> this 'magic box' and everything works as expected.  The only
> thing that is strange is that the ac power supply (the thing
> that came with the sb3) makes an audible buzz or hum noise.
> It does not make this noise when plugged into an outlet in a
> house.  Is the ac powersupply being damaged?  Will this shorten
> its life?  Any ideas or similar experiences?
>
> thanks,
> Nick
>
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