{"id":6909,"date":"2013-04-01T16:24:42","date_gmt":"2013-04-01T23:24:42","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=6909"},"modified":"2014-02-05T18:55:09","modified_gmt":"2014-02-06T02:55:09","slug":"2013-04-01-tbd","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=6909","title":{"rendered":"2013-04-01 Cree 40W Equiv. LED Light"},"content":{"rendered":"

I wrote a short blog<\/a> about the Cree LED lights recently.\u00a0 Last week I bought two Cree 450 Lm (40W equivalent) LED lights<\/a> from Home Depot for ten bucks apiece.\u00a0 The UPC label number is 13959 01932.\u00a0 I installed one of them in a task light I have over my laptop, which gets heavy usage, more than 3 hours a day, probably 4 or more.\u00a0 I had been running a Philips 450 Lm LED light in this task light, and it was doing very well, no problems, no flickering, no dimming (see note at end).\u00a0 BTW, the Cree LED light package says it is dimmable with standard dimmers.<\/p>\n

The Cree light bulb looks just like a regular light bulb with a frosted glass globe, but the globe has some kind of coating that feels soft and sticky like plastic, probably to protect it against breakage.\u00a0 The package says “Safety coated glass”.\u00a0 The globe has printed on it “CREE\u00a0 2700k 450 Lumens 6W\u00a0 | 120V~ | 60 Hz | 50mA”\u00a0 The white base has a ‘collar’, a ring of fins for heat dissipation.\u00a0 The overall length of the light is about the same as a regular incandescent.<\/p>\n

I installed the Cree light bulb in the task light and turned it on.\u00a0 The color temperature is only 2700k, which is a very warm light just like an incandescent light bulb. \u00a0 It flickered slightly, so I checked to make sure it was snugly tight in the socket.\u00a0 The flickering stopped for a few tens of seconds, but then it flickered once or twice for a second.\u00a0 The flickering isn’t enough to interrupt the light, but it’s noticeable but not annoying.\u00a0 It’s intermittent, will not occur for a few tens of seconds, then may occur once or 3 times, then nothing for a while longer.<\/p>\n

I have been running the light for the weekend, where it got plenty of use, and on into this week in the mornings and evenings.\u00a0 It continues to flicker on and off, intermittently.\u00a0 The times between flickers may be a few tens of seconds to minutes, varying by what seems to be a random length of time.\u00a0 After a few minutes, just when I forget that it was flickering, it may flicker for a few seconds, then goes back into remission for awhile.\u00a0 I will continue to monitor this for awhile, and I haven’t opened the second light package, yet.\u00a0 I’m kind of apprehensive about opening it, for fear that it will also flicker, but I may open it up and use it for awhile to see if it is better. \u00a0 I think I will eventually take the bad light back to Home Depot and get my money refunded.\u00a0 If the lights are still out in\u00a0 the aisle on sale, I may buy a few more.\u00a0 Other than the flickering, they’re okay, but the 2700 color temperature means they are very much like an incandescent light.<\/p>\n

I got to thinking about the flickering, and I thought that it may be possible that the flickering is dependent on the line voltage.\u00a0 At certain times of the day, it may flicker more when the AC line voltage increases, then when the line voltage decreases, the flickering goes away.\u00a0 I’ll have to test the light and see if varying the line voltage changes the flickering.\u00a0 How?\u00a0 I think I could add a few diodes or a bridge in series with the light to drop a few volts, or even use a resistor.\u00a0 The power dissipated across a resistor with 50 mA, and 5V is 1\/4W, and the resistor would be 100 ohms.\u00a0 No problem.\u00a0 I have some 100 ohm 1W resistors I can use.<\/p>\n

Update Apr 8 – I connected the LED light to a Variac autotransformer<\/a>, and varied the AC line voltage from 90 to 130 volts.\u00a0 What’s puzzling is that now the flickering has gone away.\u00a0 I was anticipating that the Cree light’s flickering would get worse with a higher AC voltage.\u00a0 I can think of two reasons why this may be happening.\u00a0 One is that the autotransformer is causing any line noise to be removed from the AC going to the light.\u00a0 Another is that I had the LED light plugged into a remote controller.\u00a0 This is an adapter that plugs into the wall, and is controlled, on and off, by a remote ‘fob’.\u00a0 This remote controller may be causing the flickering.\u00a0 But I don’t see how; when I turn the light on or off I hear the remote controller click, which means that it is using a relay to switch the power, not<\/span> a noise making TRIAC.\u00a0 I would say that even if it is the culprit, the reason is that the Cree LED light is overly sensitive to it.\u00a0 I have been using this controller with the Philips LED light for months and have never had any problems with it, so I would not blame the controller, I would blame the Cree light.<\/p>\n

Later this weekend I removed the light from the autotransformer and plugged it back into the remote\u00a0 controller.\u00a0 I have been using it for several hours and I have not\u00a0 noticed any flickering.\u00a0 I’m wondering if it has ‘healed up’ and is now going to act normally without any flickering.\u00a0 Only time will tell.\u00a0 But one thing this has taught me: I should (again!) be wary of any low priced LEDs or LED lights, for they most likely obey the old adage that “you get what you pay for”.<\/p>\n

Update Apr 11 – I’ve been using the once flickering light a lot, and I now see no sign of the flickering.\u00a0 It looks like it has ‘healed up’.\u00a0 The only thing I can think of is there was an intermittent connection somewhere before and now it is no longer intermittent.\u00a0 I’m hoping it stays that way.<\/p>\n

Note: The Philips LED light has a frosted glass globe, but for some reason, maybe heat, the frosting cleared over a portion of the globe, which allowed me to look inside.\u00a0 The light has a second globe on a pedestal inside, about 20mm or 3\/4″ in diameter, colored yellowish orange.\u00a0 This is apparently the phosphor that converts the light from a blue LED inside of it into the white light.<\/p>\n

Update Apr 26 – Quantsuff sent me a link to a short review<\/a> of the Cree light bulbs.\u00a0 The reviewer didn’t say much about it, other than the color temperature closely matches the incandescent bulb.\u00a0 In the time since the last update my Cree bulb has been receiving steady use, and has been flicker free for most of the time.\u00a0 But occasionally – maybe less than 0.1% of the time, it starts to flicker intermittently.\u00a0 It happened a few days ago.<\/p>\n

Update 2014 Feb 4 – This evening I turned on the Cree LED light and it flashed briefly and went out.\u00a0 It had been flickering intermittently lately, very seldom as usual.\u00a0 But this time it went out completely.\u00a0 I tested it in a known working socket and it would not light, and I put a Pjilips LED light into its socket and it lit okay, so the problem is definitely the Cree.\u00a0 For certain, it has destroyed my faith in Cree LED lights.\u00a0 It has worked – even with the flickering – for about ten months, less than a year, and then died.\u00a0 I think that speaks for the quality.\u00a0 I have more than a dozen Philips LED lights in service, and none of them have had a single problem.\u00a0 I should have returned it to the store when I first found that it was flickering.\u00a0 Oh, well…\u00a0 Too late now.\u00a0 All the better, I guess; I’ll have to take it apart and examine it to see what happened.\u00a0 \ud83d\ude42<\/p>\n","protected":false},"excerpt":{"rendered":"

I wrote a short blog about the Cree LED lights recently.\u00a0 Last week I bought two Cree 450 Lm (40W equivalent) LED lights from Home Depot for ten bucks apiece.\u00a0 The UPC label number is 13959 01932.\u00a0 I installed one of them in a task light I have over my laptop, which gets heavy usage, <\/p>\n

(Read More…)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,13],"tags":[],"class_list":["post-6909","post","type-post","status-publish","format-standard","hentry","category-led","category-lighting"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6909","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6909"}],"version-history":[{"count":16,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6909\/revisions"}],"predecessor-version":[{"id":6931,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/6909\/revisions\/6931"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6909"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6909"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6909"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}