Hacker News Reader

Comment by xxs | Hacker News Reader

>or god forbid flicker

That's just terrible drivers - likely an unisolated AC with a single coil. Flicker is trivial to defeat sacrificing the power factor (just add filtering caps). Overall there is nothing hard about using constant driven high-freq (over 30KHz, so no sound interference, either) LEDs.

Side note: in the days of home video calls, you can tell how many have terrible lights as the flicker is visible on the even camera.

View on HN

The problem just is that it's really hard to find good LEDs. Maybe they're all being sold to industrial consumers, but it's been a pain to find good LEDs if you're looking for anything more "exotic". E.g. dimmable LEDs work and are available, but there is so much cheap trash out there while good brands are often sold out. And for many sockets, there's maybe one manufacturer offering it, if at all. I've had instances where only cheap vendors offered LEDs for a certain socket.

Hmm, It'd appear you wish to retrofit LEDs in existing fixtures. That's the rub - they are not designed to work well - there is so much space for a LED driver + LEDs + cooling + looking nice. Most LEDs are overdriven to show higher lumen numbers (and watts) on the tin, which means a short life. Dimmable LEDs with a standard triac based dimmer for incandescent bulbs is a bad idea overall.

The decent LED fixtures are designed to be a single unit, e.g. near ceiling light, dimmable w/ remote/blue tooth. Unfortunately, not possible to replace parts of them, and if they are poorly built - also overdriven. OTOH, they are trivial to repair with some electronics background - often times, the driver is replaceable entirely.

LEDs need to stay cool (below 60C) to have prolonged life - say 40K hours to stay at 80% brightness. That means large heatsinks, enough space to dissipate the heat.

I've already replaced dimmers to work with LEDs. But changing all fixtures would be way too expensive, it'd then be cheaper to just stick with Halogen. And I don't need any "smart" features, an LED that can be dimmed via an external dimmer would be enough. But they're harder to find than all these "smart" devices that might stop working after a few years and can send data to who-knows-who.

>I've already replaced dimmers to work with LEDs.

While not impossible - the LED driver is a switch mode power supply, most of them would be universal one taking 90V-260V with rather variable frequency. What dimmers do - they chop the sine wave, normally that would not affect too much the driver (aside made them hot or require more bulk capacitance, which they lack) - so they have to know that the sine wave was chopped and react by reducing the duty cycle, reducing the brightness of the LEDs. That complicates the driver, however if you don't keep the LEDs at full brightness and they are not hot on touch - they should last.

The other option would be communicating through the zero cross of the sine wave, but I doubt very much it's the case.

The external dimmer is not a smart feature but more like necessity, unfortunately.

Check these out:

[1] https://www.osram.com/ecat/Professional%20LED%20lamps%20with...

God, LEDs must be the worst scam foisted upon us by governments. Flicker, lies about the lifespan, and now you say I must replace the entire lamp when it fails rather than just the bulb.

I don't think there's any malice. They're far superior when it comes to energy consumption. And they generally work well. They're just part of a general trend that it's hard to find high-quality products anymore. Unless you have industry expertise, it's extremely hard to determine which appliances are usable. Traditional DYI stores sometimes provide that expertise, buying online it's nearly impossible to search for quality.

It is malice. The government wants you to consoom while simultaneously lowering your quality of life. "Traditional [DIY] stores" are something else the govt is desperate to get rid of.

> LEDs[' dark sides]

...Interference with medical equipment (this lab I knew found out that their EEG malfunctioned when the new lamps were on...)

Poorly built drivers, yet again - no EMI suppression. Virtually any switch mode power supply that has no suppression would have done that. The LED driver in virtually all cases is some SMPS.

I know one of the tricks to detect flickering: look at the emitter through a camera, e.g. that of a phone.

How would you instead check EMI - in general? (I am not a specialist in this area.)

>I know one of the tricks to detect flickering: look at the emitter through a camera, e.g. that of a phone.

This would be a really poor driver, effectively using the AC freq. and shutting off w/ each cycle/zero cross. Unfortunately, many are exactly like that. However - some cameras do have compensation for exactly this issue, and they may hide it.

>How would you instead check EMI - in general? (I am not a specialist in this area.)

Use an AM radio. (That would depend on the frequency and what not, but AM radios are a pretty neat trick to check)

"Take an electronics testing lab with you next time you go shopping to be sure you're not getting some cheap crap"

I miss the days of a restive wire shoved into the AC circuit.

LEDs are great when done well, corporations produce flimsy garbage. As if they have some interest in things breaking apart so you have to buy new ones.

I just want LEDs that don't noticeably flicker (i'm talking 3Hz here) after a year of operation.

My bet: terrible capacitors and the driver ran hot (which caused the laps to leak out). Bad driver.

Honestly I have no clue why LED light are so poorly built nowadays. There is absolutely no technical reason for it.

Reply on news.ycombinator.com