5 ms·
Two other areas for additional inquiry: 1) Flicker: does the LED's high-speed flicker play a role in damage to the eye? (Here's an LED viewed in slow motion:
by nostromo 10y ago
Two other areas for additional inquiry:
1) Flicker: does the LED's high-speed flicker play a role in damage to the eye? (Here's an LED viewed in slow motion: https://www.youtube.com/watch?v=3wdljou1M8Q https://www.youtube.com/watch?v=3wdljou1M8Q)
2) Spectrum: LEDs can have very uneven spectrums with spikes at particular frequencies (particularly in applications like street lamps that don't use phosphors). This is something an eye in nature would never experience.
Here's a great video showing LEDs strobing compared to other bulb types: https://youtu.be/1IDf16R_eJ0?t=13s https://youtu.be/1IDf16R_eJ0?t=13s
- Freestyler_3 10y agoIts funny, I replaced 2 spot lights in my kitchen with leds and when I use one certain kitchen device (high speed rotation thing) the leds start flickering visibly.
- lightedman 10y agoOne or the other doesn't have proper grounding or the cable for power to your appliances is run too close to your cable for lighting (which should be on separate circuits, mind you!)
- Freestyler_3 10y agoDifferent rules here. There is proper grounding, but both the device and leds do not use grounding. Grounding is just for the metal cases, the lamp holder for example.
- lightedman 10y agoProper grounding regardless helps eliminate this. https://www.youtube.com/watch?v=l6bTSJVLCVI https://www.youtube.com/watch?v=l6bTSJVLCVI - I used to build fully-functional hydroponics buildings from the foundation-up. Electrical included.
- Freestyler_3 10y agoHow do you ground a light bulb, and a motor inside a plastic case? Ground is for safety in AC, when there is a short the ground should take the current away resulting in power loss through the earth that in turn makes the breaker flip. Without grounding the wire that is exposed and touching something will (depending on material etc.) not transfer any current because of too high resistance, then as you touch it it will shock you and then the breaker will go off. (A loss power breaker, not a draw power breaker) Perhaps you mean the neutral?
- lightedman 10y ago"How do you ground a light bulb, and a motor inside a plastic case?" Same way you complete any other ground - since ground and neutral are literally on the same leg (go look at any installation. You've got TWO wires coming in at the mains, ungrounded.) So, tell me, how do you ground those ungrounded 240/277V wires?? You don't. Both of them ARE the natural ground dependent upon whether you're at the peak or trough of the waveform. That's kinda how AC works.
- Spare_account 10y agoground and neutral are literally on the same leg (go look at any installation. You've got TWO wires coming in at the mains, ungrounded.) Forgive my ignorance, I'm no electrical expert, but did you just say that the ground wire is connected to the neutral somewhere in the circuit? Or did I misunderstand you?
- lightedman 10y agoThat's exactly right. Ground is always tied to neutral in a single-phase 120V installation. Open your breaker box and remove the front panel. You'll see it. http://i.imgur.com/hCY1jV0.png http://i.imgur.com/hCY1jV0.png EDIT: That "always" is assuming the house is modern wiring and not older-style two-prong wiring for the wall outlets. Those systems were just main and neutral at the box and controlled by a fusible link.
- Natanael_L 10y agoThat device must be causing the powerline voltage to dip harder than normal (or otherwise screw with the voltage waveform), more than the capacitors in the AC/DC converter for the LED lights are designed to handle. And thus uneven current = flickering light.
- alexpoulsen 10y agoThe LEDs should be in 2 or more groups that each pulse at AC speed but offset by a fraction of the wavelength, that way there is little to no flicker. Or convert to DC and power it that way.
- lightedman 10y agoThat's WAY too complicated. Just run the power through a high-frequency tank oscillator to convert from 60Hz to a much higher frequency with just a coil and capacitor. Or, do what I did. Just make the rectifier directly out of LEDs itself - https://www.youtube.com/watch?v=jDnCHyF7o5U https://www.youtube.com/watch?v=jDnCHyF7o5U And from there you can power your devices with the leftover DC power. LEDs are seriously far more robust than they were a decade ago.
- rahimnathwani 10y agoWhat's the frequency of the 12V AC supply in that video? Is it the same as 110V AC going into the transformer? What is causing the lights to pulse every few seconds?
- lightedman 10y agoYup, same 60hz power mains, it's a simple 10:1 step-down transformer with a resistor and filter cap wall-wart. My camera is recording at 29.97 FPS so you get to watch essentially which sets of diodes on the rectifier are operating on the waveform peak/trough (or would actually see which ones had I had this on an o-scope.) The weird star-trek transporter effect is just the intensity of the lights screwing with the camera + the progressive-scan nature of the camera sensor. Here's one directly on the mains power. NO CONTROL CIRCUITRY. https://www.youtube.com/watch?v=AE9QkHmeA-o https://www.youtube.com/watch?v=AE9QkHmeA-o
- gubby 10y agoNot sure this makes sense, when you PWM something like an LED, there is no 'leftover DC power'; the energy unused by the LED each cycle is not wasted.
- ScottBurson 10y agoFluorescent and gas discharge bulbs also have very spiky spectra. It doesn't seem like the spikiness is a problem in itself.
- jacobolus 10y agoFluorescent lamps are also very unpleasant, for the same reason, as are “neon” signs if you look at them up close. Sodium lamps are much less objectionable because their spectral spikes are at much longer wavelength.
- Timethy 10y agoIn my opinion neon lamps emit the most pleasant colors to look at. The only sodium lamps I'm familiar with are high pressure sodium, which emit a garrish orange hue.
- lallysingh 10y agoTo look at, or read under?
- fjrieiekd 10y agoThis is why I didn't jump on the spiral CFL bandwagon and why I won't jump on the LED bandwagon for some time to come. Good old-fashioned incandescents may be less efficient to run in summer, but they are heaven to my eyes compared with the crap being sold today. I'll gladly pay for lighting that doesn't make me nauseous or make everything look horrible.
- Brakenshire 10y agoDecent LEDs have very similar spectra and colour reproduction to incandenscent. And everyone on this forum stares at LED or CFL light whenever they look at a computer screen.
- fjrieiekd 10y agoWhich bothers me less, as it's much darker, contains less blue light with flux or night shift, and doesn't flicker as many bulbs from the hardware store do.
- Natanael_L 10y agoLook for high CRI neutral or warm LED lights.
- fjrieiekd 10y agoThere's still the flicker and glare, and an unnatural "look". LEDs are not as bad as CFL's, I'll grant you that, but still not as good as an incandescent for the living room or bedroom.