While we don’t usually post much that isn’t a new episdoe, we also usually don’t get such high profile guests on our show. This coming Monday we’ll have the Director Advanced Optoelectronics at Cree, John Edmond, on the show! We also decided its better to tell people who will be on our show beforehand instead of trying to surprise people, as we did with Joe Grand and Jack Ganssle. If you have any questions about the LED industry, Silicon Carbide and other crazy materials or anything else that the technical founder of an LED company might be able to answer, please leave it in the comments. Thanks!
You are here: Home / Administrative / Reminder: Get your LED based questions in for John Edmond of Cree
I heard somewhere that there is a patent on using PWM to control the brightness of an LED. Do you know out that’s true? Do you agree that it’s ridiculous?
I recovered a few laser LEDs from DVD drives. Can I just power them using a current limiting resistor, or do I really need an LED driver chip?
Hoping for an enlightening show. 😉
When will LEDs supplant CFLs?
In the past I’ve read a couple of LED datasheets and a critical piece of information that I’m interested and couldn’t find is expected lifetime. What’s the expected lifetime of most of the LEDs and where can I look for very long life LEDs? (The longest life I’ve heard so far is about 20 years when being used continuously.)
I think Cree will make a winner with making a complete lighting solution, that replaces a standard flourescent fitting. It should be the same footprint, have similar light output and distribution, look similar, have the same long life as a magnetic solution and a similar cost. That will in short order take over the market.
At present the big letdown is the electronics, the LED modules themselves are very good and pretty reliable unless they are used in a poor design or with marginal heatsinking.
I’d like to ask Mr Edmond what his view is on the fact that the Chinese have a hold on almost all of the resources for producing electronics.
Does he see this as a threat?
An interesting question (and a cross for the rant category on the sheet 🙂 ) should be the effect of the temperature to the lifetime, or rather what Cree has to say to it and if they (can) impose design requirements on companies that use (and advertise with!) their products.
On the consumer side of things 3W and 5W LED (230V, GU10 halogen replacement) are dying rather quickly, usually within 2 years.
Another question would be the light quality.
Everyone does cold white, warm white is more expensive but also often of a varying quality. (Ok, not so much a problem with Cree.)
So is there still room for improvements? The spectrum of incandescent light is still quite different.
Ok I have two questions:
1) In the now typical scheme of Solar Panel -> batteries -> lights, do you act in favour of a full DC operation?
2) for the more classical scheme of AC/DC converters for home/office use, can your company supply all the products as separate items for electricians to install? (that’s because I have seen them only as full kits)
and as a general topic: are constant current AC/DC converters the way to go?
I have a Acer H5350 projector which uses a lamp that runs at 2000 ANSI Lumens brightness. When I next need to replace the bulb I was thinking it might be better to replace the lamp unit with a Cree LED.
1) Which Cree LED would you John recommend?
2) What type of cooling would he recommend? The projector has a fan already to cool the bulb, but would fixing the Cree LED to a peltier and heat-sink do the job?
Thanks
I’d like to know what prevents us from having super friggin’ huge LEDs that would be able to replace spotlights and such. I dream of making an LED death ray one day 🙂
Also, what do you suppose the LEDs will be like in 10, 20 years?
I have several projects I want to build out of these bright, fairly cheap LEDs that have been appearing lately. I understand enough to put the right current limiting resistors, but I don’t know when I’ll need heatsinking or simple ways to do it. I will be building things with lots of patterns in strings of LEDs(so they won’t be on full strength all the time). A couple of the applications are on clothing, so bulky heatsinks would not work at all. I am not a real EE. I am a software guy who plays with hardware. Can he offer any advice?
I am looking at using the Piranha LEDs from Lady Ada. They are $20 for 25 of them. Are there comparable CREE products and where can I buy them at a good price in low volumes? I’ll buy 25 to start and expect to buy just a few hundred more after my design is worked out. I know that is small potatoes to most sellers.
My wife works for part of the Zumtobel group (Thorn lighting uk ) and was given as free sample of a Ledon Lamp http://www.ledon-lamp.com/en/index.htm.
We tried it for a while but had to remove it after a few days because the dimmer was getting rather warm. Why? because this particular lamp is NON DIMMABLE and a fire hazard if used in such a way. It was not evident from the packaging nor indeed from the web site unless you dug around a bit. Should this limitation not be more prominent in the public eye? or only dimmable ones allowed to be sold? Even the dimmable ones are only compatable with a range of dimmers so how is Mr Joe Public to know?
Link for Dimmer info http://www.ledon-lamp.com/en/dimmer.htm
A Little scary Huh!?
Dear Free Thinker,
Having read your comment and being in Thorn UK’s marketing team I would be interested in talking to you or your wife for more feedback etc. I have contacts with UK contact at Ledon who may be interested as well.
Regards
David
@David Blair, I’m afraid that direct contact is not an option, ( No Names no pack drill…) However every thing I have said above is confirmed on the Ledon website (apart from my specific overheating problem) My point is that this information is NOT clearly displayed and In my view is a major potential safety hazard if ignored. When you cannot get Joe public to to fit the correct fuse in a plug, to expect them to understand and correctly deploy lamps that operate in two different modes and ensure compatibility with there existing installation, is a big ask. If you feel that I am incorrect in my appraisal please feel free to enlighten me (and the rest of the world) as to my error. I’m not trying to berate Ledon, I’m sure that ALL Led based lights work in a similar manner and will suffer the same problem no matter who makes them. What I am asking for is clarity in the correct use and installation and adequate warnings of any inherent dangers. These are NOT a simple plug in replacement for tungsten lamps and we need to be informed how to use them safely.
What are your thoughts on TM-21? Do you think that LED projected life will be “stuck” due to the test time (6000 hours) required and the frequency of new product in the LED world?
Also – don’t forget that Cree is a LOT more than LEDs – they’re one of the leaders in GaN power devices for RF amplifiers, other power devices, etc.
All the LED replacement bulbs I’ve seen are spot light type bulbs, halogen replacements, are there alternatives with an output more like traditional bulbs so a single LED could be used to light an entire room?