Re: Controlling Holiday Lights

[sylvan butler <ZsdbUse1+noZs_0610@xxxxxxxxxxxxxxxxxxxxx>]

On Tue, 31 Oct 2006 12:03:01 -0500, Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote:
> What does your TRIAC-based dimmer output look like on a scope?

Depends on dim level.  For 100% bright the output voltage waveform is
essentially complete (a bit of noise near 0-crossing).  For 0% bright
there is no output voltage.  At 50% duty cycle the light appears
significantly dimmed and the voltage applied to the light shows
apparently random parts of the complete sine form with a rare complete
half-cycle.

> A dimmer curve for TRIAC dimmers shows the relationship between dim level and
> offset (in seconds, radians or degrees).

For typical triac dimmers the output waveform shows a relationship
between voltage (or current) and time.  This does not have any linear or
easily calculable relationship to dim level.

> Please describe the relationship you use between your 'waveform' and the
> resulting _constant_ , non-flickering  dim level.

I have not yet attempted any perceptual coding.

sdb

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