- CFL on steroids any risk? - 4 Updates
- musician insanity - 6 Updates
- Us congress hearing of maan alsaan Money laundry قضية الكونغجرس لغسيل الأموال للمليادير معن الصانع - 1 Update
| Jeff Liebermann <jeffl@cruzio.com>: May 30 10:36AM -0700 On Thu, 30 May 2019 05:59:08 -0700 (PDT), Tim R <timothy42b@aol.com> wrote: >It's probably worse than with CFLs because of the concentrated area >where the heat is produced, right? Maybe. LED's are certainly more efficient. Lumens/watt LED 100 CFL 60 Incandescent 16 For equal amounts of light output (lumens), a CFL lamp takes 1.7 times as much power to produce that light as does an LED. That's a big difference, but not as spectacular as the 6.3 times jump from incandescent to LED. You're concerned about "heat" with measured in Joules where 1 joule = 1 watt/second What I think you want is the final operating temperature of the device to make sure that it doesn't melt plastic, degrade the LED's, destroy electronic components, or set fire to the vicinity. The final temperature has many parameters, most of which are NOT the same for LED and CFL. For radiation loss, the surface area of a CFL lamp is larger than the equivalent LED, and is therefore a more efficient heat radiator. While the LED might waste fewer watts than the CFL light heating up the room, the CFL will remove the heat from the lamp more efficiently because it has a larger surface area. The LED compensates for its smaller size by using aluminum heat sinks, while the CFL has a larger thermal mass by using ceramics. Lots of other differences making a general conclusion rather difficult. >What isn't obvious to me, having looked at the internals, is why the >orientation would have more than a trivial effect. That heat looks >pretty trapped no matter where the base faces. Also maybe. The various lamps will move heat using conduction, radiation, and convection. All three mechanisms are involved in determining the final temperature of a lamp. In a light fixture, the ability of move air through the fixture to remove the heat via convective air currents is restricted. Without air flow the temperature of the lamp will rise. If the air flow is uneven, there will be hot spots on the lamp surface. Some lamps are more tolerant to heating than others. My plastic case MR16 LED lamp was probably the least tolerant. High temperature halogen incandescent lamps are quite happy at much higher temperatures. LEDs lose half their light output going from room temp (25C) to operating temperature (100C) <https://www.lrc.rpi.edu/programs/nlpip/lightinganswers/led/heat.asp> which is why LED heat sinks are much better and larger than CFL which can tolerate higher temperatures. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Tim R <timothy42b@aol.com>: May 30 12:51PM -0700 On Thursday, May 30, 2019 at 1:36:48 PM UTC-4, Jeff Liebermann wrote: > Incandescent 16 > For equal amounts of light output (lumens), a CFL lamp takes 1.7 times > as much power to produce that light as does an LED. That's a big I doubt that's true. Flash power, the first 3 seconds of operation for an LED, might be 100 lumens per watt, but I think 60 is more realistic. > radiator. While the LED might waste fewer watts than the CFL light > heating up the room, the CFL will remove the heat from the lamp more > efficiently because it has a larger surface area. The LED compensates I'm not sure that's the case. Surface area makes a difference for both radiation and convection, but the temperature difference is what really drives the heat transfer. The plastic globe area of an LED equivalent lamp runs much hotter than the curlicues of a CFL. (I haven't measured, but that's what my fingers tell me when changing both while hot.) (and that's probably because an LED doesn't have vacuum inside the globe, it has air that's in contact with the emitters) I don't think the majority of the heat dissipation from a CFL is from the curlicues. But if even a portion is, then the orientation will make no difference. Air will flow through them base up or down about the same. |
| tabbypurr@gmail.com: May 31 03:41AM -0700 On Thursday, 30 May 2019 18:36:48 UTC+1, Jeff Liebermann wrote: > <https://www.lrc.rpi.edu/programs/nlpip/lightinganswers/led/heat.asp> > which is why LED heat sinks are much better and larger than CFL which > can tolerate higher temperatures. Heat radiation is not significant at LED operating temp. Ditto for most of a CFL, but the end filaments do run hot. All heat produced by both does get dissipated, it can't be trapped else the thing would get endlessly hotter & self destruct. Why does orientation matter? With a 20w CFL, the ballast silicon is vulnerable to high temps. Ballast down it gets cool air flowing slowly upward past it. Ballast up it gets hot air past it, reducing life expectancy. The tube OTOH doesn't care either way. NT |
| "pfjw@aol.com" <peterwieck33@gmail.com>: May 31 05:11AM -0700 The Dubai Lamp range is comprised of four LED bulbs, each of which is available in "cool daylight" and "warm white" colors. There's a 1-W, 200-lm E14 candle bulb, 400-lm E27 classic bulb and a 600-lm E27 classic bulb. Philips says it designed the filament LED bulbs to replace 25-W, 40-W, and 60-W incandescent bulbs, respectively. The bulbs run off Dubai's 220-240-V mains voltage. The above article is from very nearly two years ago. 150 - 175 l/W lamps are common in the commercial market, and readily available in to consumers with a just a bit of effort. A bit more costly, perhaps - but if one is in a region where the Utility is subsidizing prices, you may not notice. That Home Depot or whatever passes for a Big-Box store at whatever location will not be selling either the latest, nor certainly not cutting-edge technology. They WILL be selling whatever may be mass-produced at the lowest cost with the highest margins. Most of the discussions here are based on assumptions that are - at least - three years out of date. Suffice it to understand: LED Lamp drivers get HOT. These are drivers, not ballasts. The amount of heat generated is in direct proportion to the amount of light generated as function of emitting surface. Linear emitters https://images-na.ssl-images-amazon.com/images/I/41yQl0egsTL.jpg spread the emitter heat out, and allow (relatively) tiny drivers making not-much heat. Most of these lamps are also "universal" inasmuch as they may be run in any position. And, their lumens-per-watt is not massive, either. Point-source emitters such as the CREE XHP35 will make up to 706 lumens at 350 ma. - which translates to 183 lumens per watt. Really. And that was introduced in 2018, and is commonly found in your MagLite, if you want a "real world" application. It runs at 150C at the junction - which is tiny, so that heat is easily managed. And as it is a direct DC device, there is no separate driver in a flashlight application. In a lamp application, that driver gets quite complex as that same emitter may run anywhere from 5500K with a CRI of 50 to 2700K with a CRI of 90. The technology is still evolving. And it is NOT where it was even a year ago. Tabby, for the record, you give us all a deeper understanding of the term "invincible ignorance". Thank you for that! Peter Wieck Melrose Park, PA |
| bitrex <user@example.net>: May 30 04:07PM -0400 A guy on social media (natch) who had a faulty Korg Oasys ($8000 synthesizer) trying to DIY repair the switching power supply, and posted photos of himself having extracted the fucking primary-side PFC boost filter cap, 470uF 450 volts, having convinced himself this was the faulty part because it didn't read exactly 470uF on a DMM. |
| Ralph Mowery <rmowery28146@earthlink.net>: May 30 05:54PM -0400 In article <cKWHE.23924$S33.19384@fx14.iad>, user@example.net says... > photos of himself having extracted the fucking primary-side PFC boost > filter cap, 470uF 450 volts, having convinced himself this was the > faulty part because it didn't read exactly 470uF on a DMM. Wait for him to find a new one that measures exectally 470 uF. Almost no component will measure exectally what it is labled. You just have to know with in reason how far you can go in the circuit and it still functions like it should. Chances are he could use 2 different meters and they would show up different. |
| bitrex <user@example.net>: May 30 07:17PM -0400 On 5/30/19 5:54 PM, Ralph Mowery wrote: > still functions like it should. > Chances are he could use 2 different meters and they would show up > different. He said it read 440uF. on a cheap DMM capacitance function not tested anywhere near the voltage it's normally operated at I expect it's fine. He thought it was the 12 volt bus filter capacitor, too, and not the kind of cap that can store enough energy to kill someone that it is. I figure it's usually worth at least an attempt to save that guy from himself but they tend to double down "well see. already ordered the part bro. don't tell me this Mom-stuff" Anyway many Americans like this one also believe the government is out to get them..yeah well maybe it is maybe it isn't but sanity starts at home |
| John-Del <ohger1s@gmail.com>: May 30 04:51PM -0700 On Thursday, May 30, 2019 at 4:07:40 PM UTC-4, bitrex wrote: > photos of himself having extracted the fucking primary-side PFC boost > filter cap, 470uF 450 volts, having convinced himself this was the > faulty part because it didn't read exactly 470uF on a DMM. Look, everyone on the internet says it's "capacitors", so it's gotta be true. Why are you doubting him. As an aside, if there's one value of cap that always seem to read low value either after being in service for a while or new replacements, it's the 470uf - regardless of voltage. |
| John Robertson <spam@flippers.com>: May 30 05:21PM -0700 On 2019/05/30 1:07 p.m., bitrex wrote: > photos of himself having extracted the fucking primary-side PFC boost > filter cap, 470uF 450 volts, having convinced himself this was the > faulty part because it didn't read exactly 470uF on a DMM. And the technician who finally is called in to fix this will have to deal with all sorts of the cheap owner's crappy work including broken traces, ripped out feed through holes... John :-#(# |
| Rheilly Phoull <rheilly@bigslong.com>: May 31 05:02PM +0800 On 31/05/2019 4:07 am, bitrex wrote: > photos of himself having extracted the fucking primary-side PFC boost > filter cap, 470uF 450 volts, having convinced himself this was the > faulty part because it didn't read exactly 470uF on a DMM. Just let the Darwin effect take it's course. |
| Kasem A <kasemalshami@gmail.com>: May 30 04:02PM -0700 YouTube videos of U.S. Congress money laundering hearing of Saudi Billionaire " Maan Al sanea" with bank of America and The owner of Saad Hospital and Schools in the Eastern Province in Saudi Arabia and the Chairman of the Board of Directors of Awal Bank in Bahrain With Arabic Subtitles موقع اليوتيوب الذي عرض جلسة استماع الكونجرس الأمريكي لمتابعة نشاطات غسل الأموال ونشاطات السعودي معن عبدالواحد الصانع مالك مستشفى وشركة سعد ومدارس سعد بالمنطقة الشرقية بالسعودية ورئيس مجلس ادارة بنك اوال البحريني مترجم باللغة العربية http://www.youtube.com/watch?v=mIBNnQvhU8s |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
No Response to "Digest for sci.electronics.repair@googlegroups.com - 11 updates in 3 topics"
Post a Comment