Mersey Christmas Lights, maker and breaker
- Jan 6, 2019
- Box Hill North
Mark, can I interpret that as saying I can run pixels off a single power input until I exceed 7.5A (wire safety rating for 18AWG I think), or the voltage drops to 6.7V using the Spiker lights calculator? http://spikerlights.com/calcpower.aspx. Regulated pixels are 0.64W, and effective wire gauge is 23 AWG (from the excellent Ni Christmas lights video at View: https://www.youtube.com/watch?v=GpiZQLdzYbI&t=0sI have the data sheet for the regulator. It's 6.7v that is dropout.
No more spoilers til I film the magic smoke!
I'll ask around for a thermocouple or laser based thempature measurement device. I'll see how well they cope in hot conditions (like 35°C). Thats dependant on if I get a temperature measurement device!
When I do that calculation, voltage drop limit hits first, and for regulated pixels I get to about 110 pixels at 100% power, and out to 160 @ 50% or 210 pixels at 30% power. For resistor pixels, the calculator turns yellow (20% voltage drop and color problems) at 65, 100 and 135 pixels for the same % powers, and turns red (30% voltage drop and baaad) at 85, 130 and 170ish pixels. Their power consumption is also higher at 0.72W/p, which means they draw more from the power supply - but it's still well under the 7.5A limit.
So what does this mean for wiring my props? Noting that a safety margin above 6.7V makes sense, - I'll get better colour consistency with less power injection points with regulated pixels - you can go around 1.5 x further at 30%.
I've got a 1400 pixel matrix to plan the wiring for, and this gives me more flexibility and confidence in power injection location choices (doing 2 x 700 pixel runs on separate ports). Using the calculator, I now know I could do 2 injection points each and 200W power supplies at 35% brightness, whereas with resistor pixels, I'd have been limited to 30% and an extra injection point.
Thank you - and feedback welcome if I've got an incorrect assumption in the above. I've highlighted the numbers, as they're going to be a useful rule of thumb for me to refer back to.