Re: Math & excel help required

["David Buckley" <db@xxxxxxx>]

--- In ukha_d@xxxxxxx, "Ian Davidson" <ian@g...> wrote:
> Hi All
>
> Can anyone help me to produce a spreadsheet to do the following.
I've
> not put OT in the post as it is to calculate the delay used to
increase
> the dimmer brightness to make each step as equal as possible.
>
> I need to enter a time period i.e. 10mS (time taken for 1 HALF
cycle of
> a sine wave)


You can do this in a spreadsheet, or write a little basic program to
do this, but unfortunately, its unlikely to achieve what you need to
do.  (Also, if you are writing in assembler, most assemblers can do
repeat loops to build your table for you.)

In order to make dimming appear to be equal stepped, you actually
need to make the steps unequal.  Take a look at the graph at the
bottom of this page: http://www.avolites.org.uk/products/special/fd-
dimmer.htm which illustrates the relationship between percent
apparent brilliance, and rms voltage you need to apply across a lamp.

To do a quickie linear spreadsheet, one need to know how many steps
>from
(which is usually a nuimber you feed into a timer, and you want this
equally stepped), what the limit values are, and which direction to
go in.


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