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| whit3rd <whit3rd@gmail.com>: Oct 30 03:25PM -0700 On Monday, October 29, 2018 at 6:53:34 AM UTC-7, Tim R wrote: > I had the ballast in an old two tube T12 fluorescent fixture go bad. > The local big box had direct replacement LED tubes on sale, so I tried them. They wire directly to line current, no external ballast, but the tubes fit in the old tombstone connectors. Did you disconnect the ballast inside the fixture, that connects to those old tombstone connectors? > They work fine; they start at full brightness even when the room is cold, unlike the old fluorescents they replaced. BUT there is a long delay between flipping the switch and seeing them start. It's on the order of 1 - 2 seconds, I haven't tried measuring yet. Either the ballast inside the fixture has a start-cycle, OR there's some kind of switch-off that operates to prevent a power surge from frying the LEDs. That protection circuit can be triggered by the power-on transient, and take a while to reset itself. |
| Phil Allison <pallison49@gmail.com>: Oct 30 05:05PM -0700 Tim R wrote: > We've been discussing this on another forum. > Why would there be a delay? > It's not unique to mine, either, others have noticed similar results. ** Fluoro tubes are mostly used in commercial lighting and then in quite large numbers. A big inrush surge occurs when switching banks or a whole room full of tubes on - trips breakers, bad news. The time delay built into many in LED version is there so the inverter circuitry can ramp up slowly, avoiding the usual brief but large current surge that accompanies the use of magnetic or most electronic ballasts. In typical commercial applications, the tubes are switched on only *once* a day, so there is no issue as there might be in domestic use - all the LED bulbs I have seen come instantly on. Some even fade out after switch off, just like an incandescent. .... Phil |
| Tim R <timothy42b@aol.com>: Oct 31 05:17AM -0700 On Tuesday, October 30, 2018 at 6:25:47 PM UTC-4, whit3rd wrote: > > The local big box had direct replacement LED tubes on sale, so I tried them. They wire directly to line current, no external ballast, but the tubes fit in the old tombstone connectors. > Did you disconnect the ballast inside the fixture, that connects to those old tombstone > connectors? Yes. There were LED tubes available that worked on a ballast, and I considered doing that because it would allow a retreat to fluorescent if I didn't like them, or if they became unavailable. But my ballast was bad, and replacements were expensive. So I removed it and wired 120VAC directly to the tombstones. |
| Terry Schwartz <tschw10117@aol.com>: Oct 31 08:33AM -0700 Oh those troublesome holes. Takes forever to fill 'em. Insatiable. LED's are much faster than incandescents. Look at most any vehicle that has LED's in the side mirrors and incandescents in the rear turns. The timing is visibly different and painfully obvious. At least one vehicle maker has recognized this and compensated for it in the driver timing, even PWMing the LEDs during turn on to emulate the familiar incandescent "warm up". The inherent flicker in LED tail lights (and other LED lighting) bothers the crap out of me. I know not everyone sees it, but apparently my eyesight is a bit more responsive than some. I see the flicker in neon signs and various LED backlights as well. The PWM rate is designed to be faster than normal visual threshold of detection, but below the audio threshold of annoyance... that is, over a hundred HZ or so, but out of the sweet spot of human hearing, a few hundred HZ to a few KHz. It seems counter-intuitive that the visual threshold is lower than audio, but in this case, it is. The PWM rate could easily be set above the hearing range, but that has potential implications for causing EMI certification problems. We installed LED lights in our bathroom fixtures -- and one of the wifes' hair appliances modulates the LED bulbs badly. I'm not sure if I should blame the bulbs or the curling iron in this case. Terry |
| Look165 <look165@numericable.fr>: Oct 31 05:05PM +0100 Anyway, for LED you don't need aballast. It is a resonant circuit designed for HPOT generation. Kill it off and connct the LED directly to the mains '(w/o diodes). You will have immediate lightning ; it is the ballast which introduces a delay. Tim R a écrit : |
| John-Del <ohger1s@gmail.com>: Oct 31 09:36AM -0700 On Wednesday, October 31, 2018 at 12:05:24 PM UTC-4, Look165 wrote: > Kill it off and connct the LED directly to the mains '(w/o diodes). > You will have immediate lightning ; it is the ballast which introduces a > delay. How many times does OP have to say he wired around the ballast and connected directly to the AC source?? He also said he switched to LEDs because his ballast was dead. Internally, they don't connect the LED string to the AC. So first there's a rectifier, then there's an LED current control circuit of some kind. The time the LED string will be powered up will depend on the controller. O2 Micro makes a lot of controllers, and I have seen them in many LED TV supplies. There is often a short delay depending on the control IC before the string is powered up. The 8 footers I have power up almost immediately, but perhaps the controller IC in OP's tubes delay the output until the input filter is fully charged by design. Since LEDs don't put out any significant light until they reach close to their run voltage, maybe his controller just ramps up the string slower than the one in my 8 foot tubes. The fact that all his examples do the same tells me it's just the way it's designed and not a failure. And once again, he DISCONNECTED the ballast and wired them directly. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Oct 31 09:44AM -0700 Please note the interpolations: On Wednesday, October 31, 2018 at 11:33:32 AM UTC-4, Terry Schwartz wrote: > Oh those troublesome holes. Takes forever to fill 'em. Insatiable. > LED's are much faster than incandescents. Look at most any vehicle that has LED's in the side mirrors and incandescents in the rear turns. The timing is visibly different and painfully obvious. At least one vehicle maker has recognized this and compensated for it in the driver timing, even PWMing the LEDs during turn on to emulate the familiar incandescent "warm up". There are LED lamps and there are LED lamps. "Responsible" makers such as RAB & Cree (and a few others) feed smoothed DC to their lamps, greatly reducing and/or eliminating flicker. Some few of the retro-lamp makers (those that require removal of the ballast and so forth) do the same. But far fewer than with the complete fixture. > The inherent flicker in LED tail lights (and other LED lighting) bothers the crap out of me. I know not everyone sees it, but apparently my eyesight is a bit more responsive than some. I see the flicker in neon signs and various LED backlights as well. Agreed on this. But, as you note, some makers take care to handle this in their vehicles. Our Ford C-Max side-mirror led signals are synched well for example. Vehicle systems can be a mixed bag, depending on how well filtered the Alternator might be. > The PWM rate is designed to be faster than normal visual threshold of detection, but below the audio threshold of annoyance... that is, over a hundred HZ or so, but out of the sweet spot of human hearing, a few hundred HZ to a few KHz. It seems counter-intuitive that the visual threshold is lower than audio, but in this case, it is. > The PWM rate could easily be set above the hearing range, but that has potential implications for causing EMI certification problems. > We installed LED lights in our bathroom fixtures -- and one of the wifes' hair appliances modulates the LED bulbs badly. I'm not sure if I should blame the bulbs or the curling iron in this case. See the first instance. We tried (cheap, as in FREE) some utility-supplied LED lamps in the kitchen at our summer house - and instantly lost FM reception anywhere within a 30' sphere of these lamps. We switched over to SMT LED fixtures (no separate lamps) and all became well. I will soon find out a lot more about LED retrofits. We are about to install about $1,500,000 in conversion fixtures and retro-lamps in the buildings I manage based on a fairly chunky Utility rebate. These are medical offices, outpatient clinical spaces and heavy-duty research facilities - gene splicers and all that. So, if there is any tendency for mutual interference, I will know soon. The installer says not. Famous last words, or not. It is a very mixed bag, and one size does not fit all. > > Steve > > -- > > http://www.npsnn.com Peter Wieck Melrose Park, PA |
| dhaneshwar.genesis@gmail.com: Oct 31 03:41AM -0700 OLED.pngGlobal OLED Market was valued at USD 21.01 Billion in the year 2017. OLED market is further estimated to grow at a CAGR of 14.27% from 2018 to 2023 to reach USD 46.79 Billion. APAC region holds the highest market share in 2017 with European region is considered as the fastest growing market in the forecasted period. At a country level, South Korea is the biggest market in 2017 and it is projected to grow at a gradual pace in the coming years. http://bit.ly/2q5SJlL |
| gregz <zekor@comcast.net>: Oct 31 07:09AM > Mixing with petroleum jelly should slow down the reaction so that it > turns to goo after it's sprayed on the parts that needs lubrication or > rust protection. The spray action is different from many aerosols. You can get a very controlled slow output that actually seems to bubble out. It covers parts nicely. Greg |
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