recessed LED lights for kitchen ceiling

[remauto1187]

Due to resistive losses, the power delivery conductors for DC still need to be kept relatively short. The only reason I'd wire my house up for DC power delivery from a centralized location would be if I had some form of RE energy that started life as DC in the first place. I am contemplating a way to switch all of my DC lighting loads over to a centralized battery bank for a form of home UPS system for lighting only in the event of a power outage such that the lighting functionality at the switch location would remain identical AC or DC, but without local power generation in the form of wind or solar, that would be pointless for the moment. Until then, the lighting power will be kept AC to the switch and then converted to DC in the room where it will be used.

I'm also a little leery of going full smart-house where the switches on the wall do nothing with regard to the lighting loads themselves, but rather just signal the central computer to actuate a relay in the equipment closet. I did dig this hack on Hack-a-Day a couple of weeks ago: Remote Servo-controlled Lightswitch. Light switch functionality remains identical, but the central controller could exert itself on your behalf if you program it to.

Overcome the resistive loss with BIGGER wire. Transistor control will take care of the DC/AC mirrored control. Big blovking diode will keep the AC out the DC side. A PLC can be your "centralized controller" and are in thousands of factories. I have a box of them. Want one?

 

[CathyInBlue]

I was just brain storming how I might network a bunch of different LED lights in, say, a living room. A) Crown molding up lighting, tied into bookshelf down lighting B) Ceiling fan light, and C) Eyeball recessed lights. It would be pretty trivial to have a PWM controller on each lighting set to just modulate the power the single PSU is feeding it, but how to control those PWMs? I'm trying to imagine from the PSU a 6-conductor cable daisy chaining and branching out to hit each emitter. Two (big) conductors would be the LVDC power. The other four would be a separate LVDC power supply (prolly DC-DC from 12 to 5) for the controllers and then a serial data and serial clock pair for I2C/SPI or else a LVDS +/- pair for something like CANBus.

Once you decide to add a PWM dimmer to your LED light fixture's power supply with a microcontroller, lots of other possibilities (and complications) open up. I'm imagining replacing the pull chain power switch in the ceiling fan light with a momentary pull chain so the µc could set its dim state to anything based on the length of time the chain is pulled. If the chain is pulled briefly, it could round-robin toggle between off, 33% 66% and 100%, similar to the fan speed pull chain.

It would also be trivial to add a pair of servoes to the eyeball recessed lights and you can remotely aim them anywhere you want without getting up on the ladder. Add another controller to the net with an IR imager and with an IR keyfob, the nearest eyeball could be aimed at wherever the keyfob is in 3-D space.

I still don't get how to use an AC power switch with dead AC power to switch DC power around an unpowered PSU. Presumably, you have DC power coming from somewhere else, but I'm just not seeing the electro-mechanical workings here.