Jerry Stuckle wrote:
On 11/29/2014 4:30 AM, Rob wrote:
Jerry Stuckle wrote:
For incandescent, yes. But not for LED bulbs. If that were the case,
why would some LED bulbs be dimmable and others not?

"is it dimmable" refers to the use of a phase-cut TRIAC dimmer in combination
with a retrofit LED bulb designed to run on mains power.


No, some bulbs are not dimmable, period. Some are. None work reliably
with triac dimmer controls.

Maybe not in your world, but here we can buy TRIAC dimmers and LED bulbs
that work together.

You probably have a 13.8V stabilized DC supply in your shack.
Can you use it as a variable-voltage supply by putting a dimmer in
front of it?


Completely unrelated. The LED electronics and the power supply work
completely differently.

Maybe your power supply, but mine is a switchmode supply and it works
completely the same as any other. It is regulated for voltage, not for
current, but that is another matter.


There are already dimmers made for LEDs which work well. And there are
commercial systems which use low voltage to drive the LEDs. But these
are all proprietary; there are no standards for LED lighting yet.
Eventually, maybe standards will be developed for the commercial market,
but right now there is zero push for such standards.

It's going to be years (if ever) before such standards are created for
the residential market. There are too many reasons to stick with 117V
wiring.

LED is about current, not about voltage. A lighting system can put many
LEDs in series and use a higher voltage. What is important is that the
supply circuit gets separated from the bulb, so that it can be made dimmable,
externally controlled, etc and the LED gets DC current supply.

The mains here is 230V AC. There even are proposals to change that
into 325V DC or even 500V DC. Not accepted proposals with a set date,
but still. DC supply is more efficient for the home these days, now
everthing uses switchmode supplies, it can transport more power
with the same amount of copper and the same class of insulation.