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RE: Low-voltage (12V) LED lights

To: <>
Subject: RE: Low-voltage (12V) LED lights
From: "Randall" <>
Date: Mon, 15 Jan 2007 16:24:43 -0800
> You are correct, a regular wall mounted dimmer will have no reliable
> effect on the LED strips.

I guess I'm missing something here ... why is everyone convinced this won't work

LEDs are diodes, meaning they do have a relatively fixed forward voltage drop,
below which no current flows; and the drop stays pretty much the same as the
current increases from near-zero to device maximum.  But, within that range, the
light produced definitely depends on the forward current.  And, as already
mentioned, the eye will average out the light from the LED, and (generally) not
notice flicker at 120Hz.

Although there are other kinds, the usual light dimmer works by imposing
pulse-width modulation on the 60Hz sine wave.  Basically, they chop out a
variable amount of the leading part of each half cycle.  So, the LED is going to
see both reduced duty cycle, and past a certain amount of dimming, reduced
current.  They may not go completely off under dimmer control (my incandescents
won't either), but they will go from full brightness to very dim.

Only problem I can see is that some people can see 120Hz flicker or be affected
by it (headaches and such).  If I try, I can even see some LED taillights
flicker.  For task lighting, I would definitely want to both keep the LEDs where
they cannot be seen directly, and also have some incandescent lighting mixed in.


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