DEC H7822 power supply

wrcooke at wrcooke at
Thu May 12 16:24:03 CDT 2022

> On 05/12/2022 2:14 PM Peter Coghlan via cctalk <cctalk at> wrote:
> Wayne S wrote:
> >> On May 12, 2022, at 09:56, Peter Coghlan via cctalk <cctalk at> wrote:
> >>
> >> Toby Thain via cctalk wrote:
> >>>> On 2022-05-11 7:02 p.m., Peter Coghlan via cctalk wrote:
> >>>> Given the normal usage that has evolved for the terms DC and AC rather than
> >>>> their dictionary definitions, I would suggest that the current that gets
> >>>> passed by a rectifier has both a DC component and an AC component. When
> >>>>
> >>>
> >>> It does not, due to unidirectionality.
> >>>
> >>
> >> Consider the current through the rectifier as the sum of a "DC" current plus
> >> an "AC" current. The "DC" current has a steady positive value and the "AC"
> >> current varies above and below zero with a magnitude less than or equal to
> >> that of the "DC" current.
> >
> > I’m really trying to understand what you’re getting at here.
> > In practical terms, The assumption that there is a sum of a DC and AC
> > component is incorrect.
> Why? What evidence do you have that the assumption is incorrect?
> If I am trying to calculate the height a sea harbour wall needs to be, can I
> not consider the height of the tide and the height of the waves separately
> and add them together, just to make it easier to work it out even though I
> know that it would be physically impossible to distinguish the water that
> makes up the tide from the water that makes up the waves?
> (It's not even that bad in the case of electric current because instruments
> exist which can measure the DC component of a current and the AC component
> of a current separately or together.)
You are quite correct.  It is called superposition.
It applies to all linear systems and is one of the principles that make many difficult problems practicable.
My background is primarily physics.  Superposition is extremely important there in many realms, including signal processing, electric circuits, and differential equations, among many others.

I'll say no more.  I didn't want to get into this quagmire, either.


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