.....
Don you are saying you would like to have the original AC house supply switched via the original wall light switch and going all the way to the fitting. Then a Xitanium style package, in or at the fitting, to accept AC 110 / 230 input and supply current limited DC output to the leds and also 3 levels via signalling by toggling the mains on and off, right?
Darell, if I am correct here then my concerns in post #55 still apply.
And why do you need a wall wart ?
London Lad,
Yes, that is my suggestion. I believe such a configuration will allow for ease of retrofitting LED replacement fixtures in place of incan fixtures. Since LED's just get better and better as you drop their drive current, there is no better light source for a dimmable application. When I replaced my incan fixtures with custom LED set ups, the one thing I didn't want to do was install LED fixtures that were short on lumens. As a result, I would guess in most cases, I now have more lumens than before and of course still significant savings on power consumption, regardless. Ideally, I would be able to dim these fixtures to a lower level as the typical setting for use and have the option of pumping out more light on those rare ocassions where more light would be desireable.
I would like to have access to modules that could be used in various configurations with eachother depending on the particular application. Those wallwarts Darell linked to would be such a module. The format of the wall wart or its present package is not ideal to be sure but electronically, it provides a great "front end" to take you from mains to low voltage. If the wall wart had input and output terminals like the Xitanium for instance, it would be much more useful. The Shark/Remora is a great boost converter for a string of LED's and it just needs the proper input power source.
At the start, Advance offered a driver that was a constant voltage device instead of constant current. Its output voltage was 24V if I recall correctly. Well that could be used with the Shark/Remora but your string of LED's would have to result in a Vf greater than 24V for the converter to function in boost mode. This probably means that you need a minimum of 8 LED's in the string if you hope to dim the string. If Advance made one that was 12V out then it would be viable with the Shark/Remora and the CreeStrip we have that is a string of 6 LED's.
Going modular allows you different destinations with alternate groupings of your front and back ends if I may use those terms and concepts. In the case of fixed lighting from mains, there is justification for combining the front and back end into one unit but this single unit needs to be UL and other agency approved for it to have any real marketability beyond the DIY that we play with. Like Darell has said, if you have an approved device that takes the "dangerous" mains voltage and gives you a "safe" low voltage output then you can keep under the radar of some of the regulations and standards.
With the experience I have so far messing with these components and LED lights I have seen the need for a buck back end as well as the boost. I assume that the DC side of the xitaniums are a buck converter given the fact they have rated max V out and can handle a string of LED's from 1 to
n. Maybe I am wrong?!?! :shrug:
I have been building and designing around a nominal 12 VDC supply (13.6) with my fixed LED lighting program because it lends itself well to transportation applications and there are many nominal 12VDC systems about. 24 VDC makes more sense in terms of wire gage and the ability to carry the current to the remote devices. 24VDC is more the standard for many low voltage systems like irrigation controls, solinoids and what have you. I expect that the lighting industry will be more likely to embrace 24VDC as it comes up to speed with SSL.
As a related aside, Nichia has a new LED in the works that consists of 4 dice in series. They have specs like 21 lumens at
[email protected] V which works out to about 100 lumens/watt. This is a wide viewing angle part and targeted at fixed lighting applications I believe.
On CPF, we have been engaged in different drivers as they fit and don't fit with various battery configurations and Vin's. A similar game can and will be played when the field is fixed lighting with arrays of LED's and getting from mains AC voltage down to target DC voltages wanted for conversion to constant current devices. We finally have a good range of viable LED's to work with and more are coming out every day. The hardware, fixtures and optics are pretty straight forward and again, we have good material already to work with. What seems to be lagging and the most critical is the development of the correct black boxes needed to bring life to these ideas!
I have rambled way too much here! In short, a LED light that doesn't have variable output is missing a significant dimension and attribute, IMHO. It can be a great device without volume control but can be so much more with it!!!
Since the Vin of the bFlex can be ~30V, the 18V unit works just dandy. And if you are running a bunch of emitters, all the Vf's added together need to be below the Vin anyway.
