AC/DC LED circuit

[kenny]

I was thinking of putting some 3 Watt LEDs on the outside of the house for accent lights. I was going to use either the 15 or 25 degree spread. Anyway, rather than get a power supply for the whole string (9 lights), I was thinking of just including the AC/DC converter in each light housing and then feed a DC voltage circuit.

Anybody try this? I know it's not EXACTLY flashlights, but it IS LED relatred and I thought it would be kind of cool -- plus it would use a lot less power than even the florecent ones I have installed now.

Thoughts? Links?

 

[HarryN]

Hi - accent lights are definitely cool.

A string of 9 x 3 watt Luxeons would be a lot of light
- Output something like 9x60 = 540 lumens
- Power something like 9x3 = 27 watts.
- Still a ways from being as energy efficient as a fluorescent but they are neat.

My yard lights are 12 V AC, but I am not sure about yours. I have seen a Christmas tree LED light company that put a simple FET in for each LED and used this as a current limiter / reverse voltage protection. (no idea of part numbers)

In my yard, I end up with different strings of these in parallel, so if I were doing it, I might consider trying to drive 5 or 6 VDC through the wire, and use an LDO like the Doug S posts to reach final current control.

There might be a way to do some kind of simple rectification of the AC at the point of use. International Rectifier sells a lot of parts for power management.

 

[LED_ASAP]

You will almost have to install a dedicated monitoring system to guard that string of expensive Luxeons /ubbthreads/images/graemlins/grin.gif

 

[PhotonWrangler]

Consider that an outdoor LED display is more susceptible to stray EMI from lightning strikes, so make sure that you use some heavy-duty surge suppression. Some of the tower-beacon manufacturers are learning this lesson the hard way. Granted, their products are way at the top of a 200' lightning rod, but whether they're in the air or on the ground, they're still delicate semiconductor devices.

If you do this, post some pictures of it! All things considered, I think it would look kinda cool.

 

[NewBie]

Here is some information for you and it is provided as informational only. Messing with the mains can </font> -<font color="red"> -->>KILL<<-- </font> - you. Assure on no uncertain terms that you are fused and utilize an isolation transformer, use the one hand rule, and you are experienced in working around this sort of stuff. Electrician/Technician/Engineer minimum.

For those that don't have these skills, look later, towards the end.

8-450VDC input
85-265VAC rectified input
up to 16 1A LEDs

http://www.supertex.com/pdf/datasheets/HV9910.pdf

Demo boards available:
http://www.supertex.com/feature_hv9910.html

12-400VDC
65-280VAC

http://www.supertex.com/pdf/datasheets/HV9906.pdf

Demo boards:
http://www.supertex.com/feature_hv9906.html


Here is a Luxeon "ballast" for those who are not knowledgeable and highly experienced.

Constant Voltage:
http://www.advancetransformer.com/xitanium/philips/products-913700534407.html

Constant Current:
http://www.advancetransformer.com/xitanium/philips/products-913700534408.html

Dimming:
http://www.advancetransformer.com/xitanium/philips/products-913700534404.html

A list of several different ones available:
http://www.advancetransformer.com/xitanium/philips/products.html


Here is an example of the Supertex, yes that little board on the left, a large AMD Barton heatsink, and a fan on the right, with a luxeon array:

Larger image http://www.molalla.net/~leeper/red.jpg



Oh btw, did I ever mention that I too, am a Doug?

 

[kenny]

Thanks for the info -- I sent off for a couple of sample boards -- I'm developing some outdoor lighting. I have the housing -- it fairly compact and kind of a cone shaped -- it has a weather seal and a glass cover. I was going to use some of those carclo optics (either 15 or 25 degree) and hopefully I can get the whole shebang into the housing.

I had some florescents, but they seem pretty unreliable -- first 6 of the 9 went out within the first year, and now 2 more have bit the dust (I didn't keep good enough records to tell whether they were the replacements or the old ones). I think the company's name was Amerilight or something -- I don't know how you can stay in business with that kind of failure rate. I was hoping the LED/solid-state stuff would be more robust.