Design Con 2015

ed ro

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President

Ed Rodriguez was founder/CEO of Theta-J Corp(now the Clare division of IXYS Corp). In that role he developed the optical MOSFET solid state relay, now a global defacto standard in the telecommunications industry. He is a veteran of the power semiconductor, power supply and LED lighting technology industries.Early on, before becoming an entrepreneur, he was a product manager with Unitrode (now part of Texas Instruments.) Keynote speaker at 1986 MIT national conference on advanced power electronic technology, he has published dozens of feature articles in the leading technical trade magazines. He also has been noted in Forbes and Wall St Journal. He holds 22 patents with 8 pending, virtually all involving successfully commercialized products. In 2005 , he formed OptoThermal Technologies to focus on thermal management technologies related to high-power LED lighting.


ed ro

's contributions
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • lightalog--few more comments--- At 7-8 watts you are right on the edge of acceptability, I will comment as though "I " were the one doing this-- and I am intimately familiar with all the aspects of how an led or internal power suppy may fail on the basis of thermal issues.. First of all, in a high ceiling room, there will tend to be ever so slightly more air currents than near floor level--- a good thing. The slightest air movement can drop the bulb temp a few degrees making it seem like the wattage (and consequent heat generation) is 5-10% lower than it actually is.. Needless to say , if you have a fan on, in the vicinity. that is a big help. Again, if it were me, I would say the air circulation caused by the fan, even if not great, would convince me that led bulb, at 7-8 watts, is going to be OK,maybe operating 20-25% cooler (making it act more like a 4-5 watt bulb) than if no fan at all. There really is no mystery to these things. If it were me, I would check the temp of the base of the lamp with fan off ( after first leaving the bulb on for 45 minutes) and then check it again with fan on (again after 45 minutes).I assume with you arangement it is easy for you to confirm that with the fan on, there is at least a small "breeze" across the bulb. You may not have any instrument to check temp precisely but let me say that the human finger can stay on anything up to about 45 C, If you can't hold you finger on it, it is over 45-50C. If you can hold you finger on the body of the lamp for a few seconds, it is absolutely running safely. If you can't, it still likely is OK with fan on.
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • lightalog--- no the situation has not changed one bit. If you put an led bulb having more 8-9 watts (not watts "equivalency) base up --or even base down, in a fairly tight enclosed fixture you will severely compromise bulb life expectancey becassue the air will becne tgemp elevated inside and the bulb will not be ableto properly cool. If you put base up in a NON enclosed fixtrure, the situation is much better, especially now that bulbs are getting more and more effiecient and needing fewer watts for same lumens. If you go to Lowes, you will see a number of 3-4 watt ( approx 300 lumen) candelabra base (E12) bulbs. under their housebrand Utilitech label, My son has had a half dozen of them operating just fine base up in a chandelier for over a year, and another half dozen base down, in another fixture--Both with high usage. At only about 3 watts, base up in open air is not a big deal at all-- minimal extra heating of the power supply inside. My opinion is that you would have a non problem using these lamps.So with all these LED comments, we have to be sure we donot generalize too much,. If you use lousy bulbs in an ill advised application-yes a problem.If you use right, 2014 vintage bulbs in an informed way in right application you will be just fine
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • Tarbert99 You ar so correct-- after seeing a "zillon commetns in repsonse to my orginal poice, let me maqkea final comment. Thre has been "profound" change in the arket dynamics foa 40-60 watt LED equivalent types in last 5 years.. The days of the Chinese markters seeling non ul approved, poorly specified, questonably performing bulbs is pretty much over unless one is living in a cave and buys something online and has no clue as to recent developmetns in technology and price. Today, Philips and Cree have the "default" best products on the market, legitimately specified, priced from $5-9 (depending on whether utility rebates in your area, are fully dimmable, have legit warm white or daylight" designations ,are UL approved and have intelligently designed thermal management. There is a second tier of companies, LG, TCP, Feit etc who now offer comparably priced, comparably designed bulbs. It should be recognized that 100% of all LED bulbs are produced in China--but not all are "designed" or warraned by those "faceless" China companies. Hence I woud only buy frm a cmpany with US engineering and presence of some kind I replaced all my kitchen recessed floodlights(originally incandescent halogen and then the irritatingly-slow-to-warm-up CFL refflector types--but now use Feit LED par 30 types which I bought for $5. Instant on.Feit imports form China like everybody, soetines is a littlke flaky-- hardly a Phlips reputaton but at least i know who they are as a US marketer so I felt on balance their product OK (since I know how to assess. But my pount of all this is that the dust is settling. You can now get a legit 60 watt, instant on, dimmable LEDE bulb from a very legoit supplier for $5-6.
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • Bret--- Efficiency and heat are two different things. A 60 watt incandescnt lamp i svery inefficient and gives off a tremendous amount of heat--put under a small metal plate and it willheat you dinner.Its fi,amnent gets to THOUSANDS OF DEGREES but doe not blow out because it is mad eof Tungsten.The outer glass gets extremely hot but nowhere as hot as the light emitting filament inside. The led equivalent gives off same light but only with about 10 watts but that wattage shows up as heat in the bulb housing so you feel it--but it is still only a fraction of the heat in a 60 watt filament bulb-just that you are protected frm touching the filament by the glass outer shell. Your flashlight doesn't have anywhere near the attage or light output of the led bulb--probably only a watt or two. It does not give off more light--just seems that way.The flashlight hasa reflctor which focuses tghe emitted light into a bright spot or circle and when you look at flashlight it seem "super bright" Ther eisa differnce between light "intensity" as see by a viewer and the total light output. If you took off the reflrcto form a flasjhlight it woud only light up the room a fraction of the led bulb.Simiallry if you put the proper reflector over an l3ed bulb it woud be a dramtically brighter "flashlight" The flash light has much less light but al of it is put in one spot so "seems' brighter.Becasu erhe flasghlight is such lower power, it of course has way less heat, many led flashlights have less than a watt of heat even thougth they can project a very bright "spot"on the wall. No mystery here but there is a little bit of science.You question is common "If LEDs are so darn efficient ,why do they get hot?"--only because what little heat exists is right there for you to touch. A paper match does not give off much heat at all --- a super tiny fraction of the heat of a regular light bulb--but it sure would burn your finger to a crisp.I hope this helps.
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • there are two kinds of such photocell (lighting switcher adapter)-- I know becaus edecades ago I developed and patented a type which is today still sold in many retail channels--- th eearlier type had a "thermal relay: --a mechanical kind of circuit.,The newer ones have a circuit much like a dimmer and many led bulbs are known to respond spasmodically to such "dimmer type circuit when now fully on. So in your case , that "transition time when "just enough light to make it go on or off can briefly put it in a "flicker zone until either the light is low enough or bright enough so that adapter knows what it should do. There is absolutely no problem at all with the flicker other than if it bothers you--nothing bad can happen On the CFL's-- Probably 99% of them do not turn full -on when turned on, The "full-on" time for a CFL can range frm 10-20 seconds to 2 minutes, It is made worse by cold temps until the gas in the tube heats up. LED bulbs are 100% immune to this issue but in fact actually can 'decrease" 5-10% after turn --but you will never notice, it,.That is, at first turn on they will emit a little more light than specified and then settle back to their specified level. ON the flicker--- It is very likley that some LED bulbs willrepsond better than others. If I were you I woud make sure the led buolb I use is ine described as fully dimmable, such as the new Philips "Slimline" bulb at HomeDepot--about $9. In my opinion that is the best "bang for the buck" LED bulb on the market.
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • sktrMccluskey--- You have touched a hot button of much interest to me. I am quite involved in these kinds of issues. If this was a problem for you, it probably is a problem for guys doing similar jobs all over the country. This site is not the forum to have a lengthy technical discussion which bores others, but if you get a chance, please email me your contact info at etrod@comcast.net. From a selfish viewpoint I'd like to learn from your experience but at same time might be able to provide you with some interesting info. I am presently involved in a program to develop advanced "high bay" luminaires for warehouses. It is our premise that 99% of existing LED fixtures have a very high max-to-min ratio (NOT GOOD--wasteful) for footcandles in the floor. That means folks must use high powered,fairly close-spaced fixtures in order to meet, not the "average" light levels,, but rather the "MINIMUM" levels needed. So you end up with glare right under it and darker out a ways--but in tghe end, lousy, cost ineffective light distribution. The premise----. If one can take the same amount of light, steal from the high peak and send it to the sides,. you can establish the same min light levels, eliminate the glare and do it with HALF AS MANY FIXTURES---(translate "lower cost"). But I also wonder why your LED fixture cost was so high. Regards
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • Probably/Possibly--- beccasue what you call a ""sine wave inverter": i snot reeally a sine wave inverter. MOst so called sine wave inverters use multistep switching of power MOSFETs.THi sis typically controlled by micro controller. Very cheap inverters of the type you plug in your cigarette lighter are usual simple square generators, long known to be unacceptable for anything but totally non critical consumer use. But over the years techniques were developed to create "quasi" sine waves and finally "sine" wave. But only an actual rotating generator as used by all utilities can a true, totally smooth, sine wave. It is 99.999% impossible to do so with an electronic inverter of any kind and still have it be halfway useful. If you looked at the sine wave on an oscilloscope for AC coming out of an inverter , you would see high frequency switching going on and all kinds of noise pulses. It's possible to filter out such noise pulses but I'm sure you don't want to go to much costs and trouble I'm not saying this is absolutely the issue but it sure points in that direction. I doubt that any led lamp maker 0n the planet tests their units with AC coming from any inverter and even if they found a problem they would say inverter powered lamps only represents .000001% of market. I'm afraid you are stuck with the problem
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • 509--on your 12-18 comment--just to clarify.I have some Lowe's LED lamps, some philips from home depot and recent par 30 led floodlights from Ace hardware made in China for Feit. I also have some high performance commercial Par 30 led lamps made by Solais lighting The buzzing is not actually a comnon anymore-- and those of us who have been involved in the design of LED driver circuits inside such lamps know that when buzzing "does" occur it is for very specific reasons, most commonly poor mechanical assembly of the transformer or choke in the switching circuitry, The capacitors, resistors, transistors IC's and PC boards used in the internal circuitry cannot buzz in 99.99% percent of the cases. "Acoustic" noise (ie mechanical vibration at audible frequency) is a very well and long understood "phenomenon" which can occur in the magnetic components ( the ferrite cores of the choke or transformer) if they are not glued or otherwise fastened properly. It is caused by the "piezo electric" effect of the ferrite core material,. That property is put to good use in solid state phone "ringers. So I would be surprised if you bought a hundred LED lamps made by a name brand company in last 24 months and more than 5%" buzzed". This is just something which clearly has (or should have) the quality control awareness of the main companies such as GE, Philips, Feit,Cree, Sylvania and others But then again, anything is possible
  • 10.30.2013
  • That 60W-equivalent LED: What you don’t know, and what no one will tell you…
  • Boo-- If you check more closely you will indeed find CFLs with no such labeling I have some here. If you tell me the brand/model you said were labeled, I will respond with those which are not labeled. and by the way, CFL do not have any thermistors in them so I don't know what you meant when you said "thermistor tripped". I am also interested in your comments about using drop-in LED luminaires for 5 years since Home Depot and Lowe's did not even start selling them until 3 years ago