| Electronics > Projects, Designs, and Technical Stuff |
| LED drivers on Boeing and Airbus passenger aircraft? |
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| tooki:
--- Quote from: treez on January 03, 2020, 01:42:20 pm --- --- Quote ---Almost certainly, the cabin lighting runs off 120 V 400 Hz AC power, so not likely. --- End quote --- Thanks, someone told me that there is indeed an SMPS PFC and switcher connected to the 120V, 400Hz....but they just provide a downstream voltage rail which linear led current regulators use. --- End quote --- My hunch is that the downstream regulators are still switch-mode DC-DC converters, and that by “linear”, they mean that there is no PWM or other pulsing on the output to the LEDs. |
| tom66:
--- Quote from: Yansi on January 02, 2020, 07:19:34 pm ---No. --- End quote --- I almost ended up working for a company that created LED lighting for trains. While the power supplies to convert from the DC vehicle bus were switchmode, to the string voltage plus a few volts, the LED strips themselves used linear current regulation (usually a transistor or opamp circuit) to balance current between strips. The outputs were PWM'd. On the most recent Airbus flight I was on, the PWM of the interior lights was uncomfortably visible at times. |
| Kilrah:
--- Quote from: tooki on January 04, 2020, 08:57:44 am ---My hunch is that the downstream regulators are still switch-mode DC-DC converters, and that by “linear”, they mean that there is no PWM or other pulsing on the output to the LEDs. --- End quote --- On the RGB LED-lit aircraft I've been on there definitely is PWM, and it tends to be an annoying frequency that's low enough to notice. |
| Simon:
switch mode does not have to mean noisy, but it's a lot of work which is why the military/aero space rated regulators are more expensive. |
| tooki:
--- Quote from: Kilrah on January 04, 2020, 11:36:44 am --- --- Quote from: tooki on January 04, 2020, 08:57:44 am ---My hunch is that the downstream regulators are still switch-mode DC-DC converters, and that by “linear”, they mean that there is no PWM or other pulsing on the output to the LEDs. --- End quote --- On the RGB LED-lit aircraft I've been on there definitely is PWM, and it tends to be an annoying frequency that's low enough to notice. --- End quote --- Airbus? The only aircraft with RGB lighting I’ve been on are Boeing 787s. I’m super sensitive to PWM flicker, and though I was curious and actively tried to identify whether it was PWM dimmed, I detected no flicker, so it’s either linear, fully smoothed, or at a very, very high PWM frequency (upwards of 3KHz). |
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