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daplatapus
07-30-2012, 03:13 PM
OK, so I built my LED light and used a Dim4 board to get sunrise/sunset. But... because the LED's still light up at 0V they don't really ramp up. I put the drivers on a timer so they come on instantly (albeit at 10% but it's still quite bright) then they ramp up from there. Is there a way to put in a resistor or something to kill that 10%? So that when the timers kick in, the drivers putting out 10% are still not putting out enough to actually light the LED's yet? SO I guess in theory you'd only get 90% output of the LED at max even though the driver is putting out 100%

Smack me if that doesn't make sense, my electrical knowledge is almost 0 :P

Cal_stir
07-30-2012, 08:26 PM
unfortunately thats the nature of leds, you could set the timers so 1 set lights at a time, but what I did was got 4 blue pods for my RKE and I start them 30 min before the leds and ramp them up for 30 min, the pods start out very dim and you hardly know when the leds kick on.

martinmcnally
07-30-2012, 09:06 PM
OK, so I built my LED light and used a Dim4 board to get sunrise/sunset. But... because the LED's still light up at 0V they don't really ramp up. I put the drivers on a timer so they come on instantly (albeit at 10% but it's still quite bright) then they ramp up from there. Is there a way to put in a resistor or something to kill that 10%? So that when the timers kick in, the drivers putting out 10% are still not putting out enough to actually light the LED's yet? SO I guess in theory you'd only get 90% output of the LED at max even though the driver is putting out 100%

Smack me if that doesn't make sense, my electrical knowledge is almost 0 :P

It depends on the driver. I'm guessing you are using inventronics drivers which start at 10%?

If you were to go with some MeanWells you will get true 0-100% dimming.

Your resistor idea would not work in series as a resistor will only step down the voltage across the LEDs not the current and its the current that is controlling the brightness. However a resistor placed in parallel would do the trick however you would have to do some experimentation to see what size of resistor would be acceptable.

sphelps
07-30-2012, 09:15 PM
You could always add another small array of LEDs with either lower power or a different driver to come on first and ramp up to a point before the rest of the LEDs turn on at 10%.

Cal_stir
07-30-2012, 09:43 PM
It depends on the driver. I'm guessing you are using inventronics drivers which start at 10%?

If you were to go with some MeanWells you will get true 0-100% dimming.

Your resistor idea would not work in series as a resistor will only step down the voltage across the LEDs not the current and its the current that is controlling the brightness. However a resistor placed in parallel would do the trick however you would have to do some experimentation to see what size of resistor would be acceptable.

My meanwells start at 5% which is fairly bright.

martinmcnally
07-30-2012, 11:16 PM
My meanwells start at 5% which is fairly bright.

Hmm, what kind do you have?

daplatapus
07-31-2012, 12:03 AM
Yeah they are inventronics. 2- 40W and a 25W. If I switch out to Meanwells you're saying I'll be able to ramp from 0% with the dim4 board?


It depends on the driver. I'm guessing you are using inventronics drivers which start at 10%?

If you were to go with some MeanWells you will get true 0-100% dimming.

Your resistor idea would not work in series as a resistor will only step down the voltage across the LEDs not the current and its the current that is controlling the brightness. However a resistor placed in parallel would do the trick however you would have to do some experimentation to see what size of resistor would be acceptable.

Cal_stir
07-31-2012, 12:13 AM
Hmm, what kind do you have?

ELN-60-48D

I use a RKE with an ALC for sunrise/sunset