[sdiy] switching LEDS

[db]

I'm a bit confused by what you say.
Why is current source any issue if I just turn them on and off with a 
relay, or is that just if I wanted to alter brightness?

Can I switch the signal from the LED driver? Or do I need to switch the 
input to a single LED drivers for each LED.
I see some low cost drivers that handle 4 LEDs.

was thinking about making it with something like this
http://www.futurlec.com/Relay_4.shtml
but I guess variable brightness would be nice.


At 1/11/2010 10:53 AM, ASSI wrote:
>On Monday 11 January 2010, db wrote:
> > Now I want to switch very big LEDs like 5-10 watts, so I'm sure I
> > need to add something like a relay to keep it all safe and
> > isolated. I guess I could use small relays, but is the best way to
> > use some kind of solid state relay?
>
>Driving high-power LED is tricky business if you want to use them
>anywhere near their maximum output.  You can't just "switch" them as
>they really need a constant current source.  Trying to provide this
>via a resistor would create a space heater and a linear regulator
>would still throw a considerable amount of heat.  You'll be much
>better off using a dedicated high-brightness LED driver IC that
>creates a constant LED current via DC-DC-conversion.  They come in
>many different configurations, you'll likely want to use one that has
>a single LED enable (so you don't need a digital interface like I²C or
>SPI just to switch the LED on or off) an analog dimming signal to
>optionally regulate the brightness.
>
>
>Achim.
>--
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dennis.barton:skylab2000[socal]