I stumbled on a good deal on eBay for Seoul Semiconductor Co. SSC W42180-05 P4 Z4 1W 350mA 100 Lumens White LED bare emitters, and bought ten.
Then came weeks of experimentation. These are "real" parts from Korea, not no-name no-specs eBay China parts. With careful use, keeping the junction temp down with good heat sinking always, you could really get 10,000 - 100,000+ hrs of useful life out of them.
These are fine parts. In theory. But a pain to experiment with. They are quite small and really intended to be wave soldered to a heatsink surface. I had to invent a funky plastic collar-clamp to hold them to the heatsink. Attaching probes or wires to the pins, while avoiding heat or stress damage, is not so easy. The translucent encapsulation is disconcerting semi-squishy silicone, not familiar hard epoxy. The light beam is very wide-angle, Lambertian.
Plan on at least 10 square inches of effective heatsink surface area per watt. You need a nice flat surface for coupling to the bare emitter base, and nice thick hunks of copper or aluminum for the heat to flow well, and plenty of surface area to unconstrained free air to actually get rid of the heat. The bare emitter bases are not electrically isolated, so each LED needs separate heatsinking, or you need to add an insulation layer, which will impede heat flow. Oodles of design tradeoffs.
I made some experimental under-cabinet lighting, using hunks of extruded aluminum track lighting for heatsinking. I also did some spider clusters of pennies, solder-assembled on the stove burner. The pennies turned dark, but the clusters seem functional. They don't work as well as I hoped, maybe because ten pennies just is not enough surface area, maybe because mounting the LEDs with CA superglue did not work out well thermally. I hope it is a long time until I try superglue again; getting your fingers glued to penny clusters is only funny when you are not actually dealing with it, trying to open the new bottle of acetone fingernail polish remover with one hand. (You did plan ahead for accidents, didn't you?) Acetone does not actually work so well to dissolve CA...
After mounting the prototypes under kitchen cabinets with velcro to light the counter surface area, and running them at conservative currents, the amount of light was very impressive. The wide beam angles was fine for those short distances, helped avoid hot spots. And the LEDs are so efficient that they can be run at very low currents and produce plenty of light for an always-on background light mode, at a very low annual cost (if the power supply is efficient at low current levels). You can insert a switch at any convenient point in a series-string loop, arranged to short a largish series resistor -- nice to have that freedom on where to put the ON switch.
But lighting the rest of the kitchen is much more challenging. The stove area has the problem that any LEDs in the stove hood are going to catch the heat from the stove/oven, a Bad Thing. The rest of the lighting needs to project down from the 8-foot ceiling. The wide beam of the SSC P4 is not what I want -- I want to optimize efficiency (and cost) by putting most of the light right where I need it. Messing around with reflectors or lenses for the SSC parts, which already are so inconvenient to use, does not seem like a good choice.
I thought I should give up on high-power parts and go back to my original concept of oodles of cheap 5mm LEDs. Mounting on PVC pipe should be cheap and easy. No big thermal concerns, though I was thinking of soldering each one to a penny heatsink, as close to the LED body as feasible. EBay 5mm white LEDs are extremely cheap, under ten cents a piece. Any beam width you want. If I could get a few Lumens from each, it should work fine. But these are no-name, no part number, no spec parts from China. They don't even bother to make any claims about the number of Lumens or the number of hours of useful Lumens under what conditions. jtr1962 did wonderful White Led Lumen Testing and I was eager to try JELED 55K mcd parts -- but sadly jtr1962 did not test Lumen degradation. There is lots of gossip that you are lucky to get 1000 hrs from eBay white LEDs from China. I need parts that can be depended on to last many thousands of hours with high efficiency, or there is no point going to all this work.
I was also eager to try the round 10mm 1W white LEDs from China, for a couple dollars each, since they are available with 40 degree beam width. But there is just no basis for trusting that these will give efficient Lumens and keep working well for thousands of hours -- just foolish delusional wishful thinking.
Good LED parts from reputable dealers and manufacturers are not just much more expensive -- they are also much less readily available to ordinary folk in small quantities for experimenting. Since you can't get them on eBay, you will often pay more for S&H than for the parts you want to try!
Then, I stumbled on the BridgeLux BXRA-C0360 400 Lumen 350ma 13V 4W. Irresistably priced at about $5 from Digi-Key, who will send you parts with free shipping, no minimum if you mail them an order with a check. These are reputable real parts with real specs, plenty of application notes to study, and a real hope that they will work well for 50,000 hours if you treat them right. They are larger, flat, with solder pad connections; just screw them down to the heatsink. Sounds so easy! I don't like the very large beam angle (polar), but 400 Lumens is so much light that one or two right over the sink should still be plenty of light. Digi-Key even sells a variety of fancy matched reflectors for just over a dollar each.
I am concerned by the coolish 5600K color temperature and the poor 65 CRI. They have neutral and warm parts, but they are more expensive and put out less light. We want the most efficiency we can stand, and this is a very low-budget project. Anyone have experiences with these colors in home kitchen lighting to share?
Have you tried Bridgelux LEDs? Are they as great as they seem? Does this approach to eco-cheap kitchen lighting sound like a good idea?
Then came weeks of experimentation. These are "real" parts from Korea, not no-name no-specs eBay China parts. With careful use, keeping the junction temp down with good heat sinking always, you could really get 10,000 - 100,000+ hrs of useful life out of them.
These are fine parts. In theory. But a pain to experiment with. They are quite small and really intended to be wave soldered to a heatsink surface. I had to invent a funky plastic collar-clamp to hold them to the heatsink. Attaching probes or wires to the pins, while avoiding heat or stress damage, is not so easy. The translucent encapsulation is disconcerting semi-squishy silicone, not familiar hard epoxy. The light beam is very wide-angle, Lambertian.
Plan on at least 10 square inches of effective heatsink surface area per watt. You need a nice flat surface for coupling to the bare emitter base, and nice thick hunks of copper or aluminum for the heat to flow well, and plenty of surface area to unconstrained free air to actually get rid of the heat. The bare emitter bases are not electrically isolated, so each LED needs separate heatsinking, or you need to add an insulation layer, which will impede heat flow. Oodles of design tradeoffs.
I made some experimental under-cabinet lighting, using hunks of extruded aluminum track lighting for heatsinking. I also did some spider clusters of pennies, solder-assembled on the stove burner. The pennies turned dark, but the clusters seem functional. They don't work as well as I hoped, maybe because ten pennies just is not enough surface area, maybe because mounting the LEDs with CA superglue did not work out well thermally. I hope it is a long time until I try superglue again; getting your fingers glued to penny clusters is only funny when you are not actually dealing with it, trying to open the new bottle of acetone fingernail polish remover with one hand. (You did plan ahead for accidents, didn't you?) Acetone does not actually work so well to dissolve CA...
After mounting the prototypes under kitchen cabinets with velcro to light the counter surface area, and running them at conservative currents, the amount of light was very impressive. The wide beam angles was fine for those short distances, helped avoid hot spots. And the LEDs are so efficient that they can be run at very low currents and produce plenty of light for an always-on background light mode, at a very low annual cost (if the power supply is efficient at low current levels). You can insert a switch at any convenient point in a series-string loop, arranged to short a largish series resistor -- nice to have that freedom on where to put the ON switch.
But lighting the rest of the kitchen is much more challenging. The stove area has the problem that any LEDs in the stove hood are going to catch the heat from the stove/oven, a Bad Thing. The rest of the lighting needs to project down from the 8-foot ceiling. The wide beam of the SSC P4 is not what I want -- I want to optimize efficiency (and cost) by putting most of the light right where I need it. Messing around with reflectors or lenses for the SSC parts, which already are so inconvenient to use, does not seem like a good choice.
I thought I should give up on high-power parts and go back to my original concept of oodles of cheap 5mm LEDs. Mounting on PVC pipe should be cheap and easy. No big thermal concerns, though I was thinking of soldering each one to a penny heatsink, as close to the LED body as feasible. EBay 5mm white LEDs are extremely cheap, under ten cents a piece. Any beam width you want. If I could get a few Lumens from each, it should work fine. But these are no-name, no part number, no spec parts from China. They don't even bother to make any claims about the number of Lumens or the number of hours of useful Lumens under what conditions. jtr1962 did wonderful White Led Lumen Testing and I was eager to try JELED 55K mcd parts -- but sadly jtr1962 did not test Lumen degradation. There is lots of gossip that you are lucky to get 1000 hrs from eBay white LEDs from China. I need parts that can be depended on to last many thousands of hours with high efficiency, or there is no point going to all this work.
I was also eager to try the round 10mm 1W white LEDs from China, for a couple dollars each, since they are available with 40 degree beam width. But there is just no basis for trusting that these will give efficient Lumens and keep working well for thousands of hours -- just foolish delusional wishful thinking.
Good LED parts from reputable dealers and manufacturers are not just much more expensive -- they are also much less readily available to ordinary folk in small quantities for experimenting. Since you can't get them on eBay, you will often pay more for S&H than for the parts you want to try!
Then, I stumbled on the BridgeLux BXRA-C0360 400 Lumen 350ma 13V 4W. Irresistably priced at about $5 from Digi-Key, who will send you parts with free shipping, no minimum if you mail them an order with a check. These are reputable real parts with real specs, plenty of application notes to study, and a real hope that they will work well for 50,000 hours if you treat them right. They are larger, flat, with solder pad connections; just screw them down to the heatsink. Sounds so easy! I don't like the very large beam angle (polar), but 400 Lumens is so much light that one or two right over the sink should still be plenty of light. Digi-Key even sells a variety of fancy matched reflectors for just over a dollar each.
I am concerned by the coolish 5600K color temperature and the poor 65 CRI. They have neutral and warm parts, but they are more expensive and put out less light. We want the most efficiency we can stand, and this is a very low-budget project. Anyone have experiences with these colors in home kitchen lighting to share?
Have you tried Bridgelux LEDs? Are they as great as they seem? Does this approach to eco-cheap kitchen lighting sound like a good idea?
Last edited:
