--- Dieter Doepfer < hardware@... > wrote:

> From: "Dieter Doepfer" < hardware@... >
> To: "Bakis Sirros" < synth_freak_2000@... >
> Subject: AW: 1 PC Power Supply Unit
> Date: Fri, 19 Sep 2003 12:36:16 +0200
>
> please forward
>
> > youll get me in all sorts of trouble if im
> wrong... ;)
> >
> > can anyone shed more light on it i dont fully
> understand, but ive seen,
> on
> > the synth diy list, people always warning against
> "switched" psus, and
> > recommneding "linier" insted, like, for example,
> the "power-one" units.
> >
> > if anyone knows more about this, both of us would
> be interested, for sure
>
> 1. Switched PSU may cause undesired noise/glitches
> and so on (depends upon
> the switching frequency of the PSU, the
> subharmonics/harmonics of this
> frequency, the shielding, and the measures to
> suppress these
> noise/glitches). For digital circuits (like PCs)
> these noise/glitches don't
> matter but for audio it may cause problems. Linear
> PSU do not have these
> disadvantages. The main advantage of switched PSUs
> is the efficiency (up to
> 75% and even more) which very poor for linear PSUs
> (sometimes only 25% and
> even less).
>
> 2. For some A-100 modules exact +/-12.0 V supply
> voltage is important. Many
> switched PSUs have no trimming possibilities to
> adjust the voltages to
> exactly +/-12.0
>
> 3. Many of the PC PSUs have no symmetrical max.
> currents (e.g.
> +12V/500mA, -12V/100mA). For A-100 approximately
> symmetrical currents are
> necessary even if the positive section sometimes
> takes a little bit more
> current.
>
> Dieter Doepfer
>
>

=====
Bakis Sirros
Parallel Worlds / Polariton
Athens-Greece
1 group owner
http://www.rubber.gr
http://www.ward12.com

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