I saw an article yesterday (http://www.elektor.com/news/white-power-led-achieves-200-lumen-per-watt.126 3836.lynkx?utm_source=UK&utm_medium=email&utm_campaign=news) where a company has reached 200 Lumen per watt - they should be interesting. Owning a sailboat, I have been looking for ways to reduce power consumption (since we run off batteries when away from shore). The four 12vdc bulbs in the galley consume 6A total. I am in the process of replacing them with strips of 80 Lumen LEDs. The design uses a TI TPS61161 driving a string of 10 LEDs. The current consumption of a single string is 300mA. We are hoping that 6 strings will be enough (waiting of the LEDs to arrive) - this would cut the current by almost 1/3. I am using my CNC machine to route out the circuit board, which around the TPS61161 is really small. The TPS61161 is a 2x2mm chip with 6 pads (3 on opposite sides) - a real bugger to solder. David David V. Fansler s/v Annabelle dfansler@dv-fansler.com www.dv-fansler.com -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Apptech Sent: Sunday, February 21, 2010 1:50 AM To: Microcontroller discussion list - Public. Subject: Re: [OT]LED Light Bulb, how many lumen is enough? > Try to replace the 60W and 100W regular light bulb with "LED light bulb", > I am curious how many lumen of the "LED light bulb" shall I use? It very very very much depends on what you are trying to illuminate and how much area you want to illuminate. As a rough guide, multiply the area to be illuminated in sqare metres by the followin figures, or by 1/10th as much for quare feet. 0.5 See dimly night light 10 Usefully bright, colour discernible, not vreally enough for reading. 20 Good for color reading and detail discernment. Dimmer than some would be happy with 50 Very adequate for most things 300 Stupidly high recomended level for detai work. eg for "Very adequate for most things" over a 2 square metre table you need 2 x 50 = 100 lumen. That's about 20 square foot table so using table value/10 gives 20 x 5 = 100 lumen (of course) 100 lumen can be had from a top / very efficient modern 1 Watt LED with minimal diffuser or reflector losses. Say a top bin Cree XP-E etc. Or an equivalent xxx Dragon, Rebel etc. So to be safe about 1.5 Watts. You can do a lot of good in a "personal illuminator" with 15 lumens! :-) To light a 3m x 3m = 1 ' x 1-' room to "Good for clour reading" needs (3 x 3) x 20 = 180. Say about 3 Watts. Note that this is if you can get all the light evenly distributed and with minimal losses and with a highly efficint LED giving 100+ lumen/Watt OUTPUT. Real Worls modern LED bulbs are unlikely to give much more than about 70 l/W - about the same as a good modern CFL. Note that these levels are below what people are generallyt used to, even though the brain will handle them very well with time. Using the 300 lumen/m^2 western guideline on the 3x3 metre room gives 3x3 x 300 = 2700 lumen of about 30 Watt. You would be very very very well illuminated with 30 W of good quality LED lighting in a 3m x 3m room :-). YMMV but that's a good start. Try buying a few top quality LEDs high angle white LEDs rated at say 1500 mA, heat sink them well, tun them at 1000 mA or so and try them out in various locations. That will open your eyes (pun only vaguely intended) to how much you can do with 3 Watts of energy - and what the real limitations are. If you want to light a very large area as with say a security spot then you need some real power. For most applications you don't. Russell ----- Original Message ----- From: "Funny NYPD" To: Sent: Thursday, February 04, 2010 7:40 PM Subject: [OT]LED Light Bulb, how many lumen is enough? > Try to replace the 60W and 100W regular light bulb with "LED light bulb", > I am curious how many lumen of the "LED light bulb" shall I use? > > Funny N. > Au Group Electronics, http://www.AuElectronics.com > http://www.AuElectronics.com/products > http://augroups.blogspot.com/ > > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist