Author Topic: Strange thougths  (Read 756 times)

Offline ronp

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Strange thougths
« on: July 02, 2016, 06:21:40 PM »
My first year I built all of my LED's custom as well as the sequencing. It was really stupid considering what was available, but I had fun. While I was doing my own LED's I did two things differently. First, I thought this is at night and I don't need to been seen from the space station, so I used 10mA per LED. Saved a ton on the power. The second thing I did was run my sequence at 10mS. I loved the runs along the roof, silky smooth. So this brings me to two suggestions for sequencing.


FIRST:
a) If you are mostly using the software to drive motion and have a few AC strings or dumb RGB LED strings the 10 hertz rate would be sufficient and would make sequencing easier.[/size]b) If you are driving mostly AC strings and dumb RGB LED's to music and want to be precise on timing the 20 hertz refresh rate is a very good choice. In fact this is basically the default used by most people.c) However, if you are using a lot of the built in sequences in Xlights to drive smart RGB LED's you might want to consider a different refresh rate. The beat in most songs is 100-120 beats per minute or about two beats a second. I have about 100 lights across the front of my house. If I want to use a curtain effect the lights are broken up into the following segments for each refresh rate.10 Hertz, 5 samples in 1/2 second - 20 lights lit per sample20 Hertz, 10 samples in 1/2 second - 10 lights lit per sample40 Hertz, 20 samples in 1/2 second - 5 lights lit per sampleLooking at the numbers above, if you want smooth effects for your light show you should choose the maximum refresh rate of 40 hertz. For me this is the best choice and since my show is not very large, it really no problem for the hardware or software.


SECOND:
Last year I had about 2500 smart pixels and my yard was like daylight. It could have been half as bright and it still would have been a fine show. The pixels we buy are designed for daylight viewing, so they have to be really bright. For us night time folks, not so much.If you look at the gamma curve for pixels, you get the following ratio's.75% power - 14% drop in brightness66% power - 18% drop in brightness50% power - 27% drop in brightness25% power - 47% drop in brightnessLast year I ran my lights at 90% brightness, and in 2014 it was at 82%. So two years ago, I cut my power by a third with a drop in brightness of 18%. I would not recommend dropping power below 50%, since as you drop the power it reduces the number of effective bits. If you do choose to reduce the maximum brightness, please check the common colors you use to ensure the shade is correct.
The interesting part about this is that at 1/2 to 1/4 current you could drive many more lights off much smaller power supplies without the need for power injection. I am surprised that nobody has thought of ordering custom WS2811 pixels with lower maximum current.
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