Re: Math & excel help required

["Paul Robinson" <ukcueman@xxxxxxx>]

Not that I know anything at all about dimming and brightness etc, but if
the
brightness increases at each step like a sine wave, then the steps should
be
at times given by a sine wave as well.

If we have n steps
and we want to get to the last step at time t
then go to step number i
at time t*sin(i/n)

This means the interval from step i to step (i+1) would be t*sin((i+1)/n) -
t*sin(i/n)

That might do what you want.

HTH
Paul

----- Original Message -----
From: "Ian Davidson" <ian@xxxxxxx>
To: "HA Yahoo group UK (HA Yahoo group UK)"
<ukha_d@xxxxxxx>
Sent: Friday, September 12, 2003 7:39 PM
Subject: [ukha_d] Math & excel help required


> 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)
> And the number of steps i.e. 100 (0 to 100% brightness levels)
>
> The spreadsheet needs to generate the time period of each of the 100
> steps keeping the increase/decrease of the amplitude of the sine wave
> the same.
>
> I hope that makes sense, easy to draw on the back of an envelope but
not
> so easy to write in an email.
>
> To try to clarify this a little more, in the example above I could use
> 100uS steps i.e. 100uS x 100 steps = 10mS
>
> This works but as you increase the brightness you see larger steps at
> the very dim and very bright as the sine wave slope is quite steep but
> at the 50% point the difference is small due to the flattening of the
> sine at its peak.
>
> Thanks
>
> Ian D
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
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