Not a video (yet). Scary voltage LED lamp.
Added 2020-06-23 02:31:27 +0000 UTCI wondered how this linear 36W lamp was achieving such a good power factor (0.95).
It turns out that it's using a driver styled as the front end of a power factor corrected supply that charges a big capacitor to above peak mains voltage as a series of pulses across the whole sinewave.
The LEDs are in a long series array adding up to 400V, so the current can't just go straight through them. It has to be boosted first. And because that happens as a series of pulses across most of the waveform it means that the current waveform has a fairly close approximation to the voltage waveform as opposed the the central current peak of most simpler lamps.
Comments
Interesting. That's a nuance of power factor that's new to me.
George Dorn
2020-06-24 13:47:47 +0000 UTCYup, that's how I work on live tube amps. Voltages easily exceeding 450V with high amounts of current due to large filter caps. Pretty scary stuff if you don't know what you're doing.
2020-06-23 23:43:26 +0000 UTCI’m building my BigClive RGB controller this evening and I only need 12 volts to light up an entire dead tree. 360 volts? Amateurs
Jim
2020-06-23 23:23:23 +0000 UTCI think this light is aimed at commercial applications. It claims to be waterproof. In bulk the better power factor could allow use of more on a circuit.
Big Clive
2020-06-23 20:12:07 +0000 UTCThey usually do arc over internally on standard mains lamps. Until they burn clear and flicker dimly.
Big Clive
2020-06-23 20:07:52 +0000 UTCIt is switchmode. Effectively a non-isolated boost converter riding on the unsmoothed sinewave.
Big Clive
2020-06-23 20:00:27 +0000 UTCIt's from CPC in the UK.
Big Clive
2020-06-23 19:59:01 +0000 UTCIf an led chip failed open at that voltage could it poss just arc clean over to keep everything working. it`s maybe the new chinese way to save money or the designer just left pre school and confusticated parallel and series
2020-06-23 13:15:52 +0000 UTCUK peak mains voltage is 340V and tungsten and halogen lamps usually fail gracefully at that, so probably not a terrible failure.
Richard Robinson
2020-06-23 12:59:12 +0000 UTCI'm both curious and terrified of a lamp failure at those very spicy voltages.
2020-06-23 12:25:31 +0000 UTCDefinitely spicy! Good that power factor is being considered though.
Richard Robinson
2020-06-23 10:50:13 +0000 UTCI had a TV here in the states that, for some unknown reason boosted the LEDs above the line voltage. They were in the 320v range, then all the LEDs were in series. When I first saw the voltage I thought that was the issue, but digging in further I noted that the leds were in series and it made more sense after I tested the forward voltage... I think the LEDs had more than one in the package but I don't remember. Seems to me out would be easier to run them in parallel, or series/parallel to keep the voltage lower and also make the system single fault tolerant to some degree, but thinking back it was a cheap tv and the thin cables coupled with the lack of fault tolerance probably says it all. I think in hindsight, I know now now than I did then, it makes sense but at the time I was a little baffled
Michael Wellman
2020-06-23 09:06:42 +0000 UTCI never though of high voyages as "spicy" before, but I do now. Adopted
Michael Thompson
2020-06-23 08:23:56 +0000 UTCWhen I left school I worked in a TV repair shop for a short time. The basic rule when working on those evil high voltage AC/DC things, when live, was keep one hand in pocket, or behind your back.
Mr B Shepherd
2020-06-23 06:31:57 +0000 UTCOne slip in poking around will leave a serious skidmark :). Is this a circuit also used in the led-tl’s?
Mike Weijmans
2020-06-23 06:19:05 +0000 UTCvery interesting when i get to 400 and over my hands shake,anyway look forward to the Video!
William Nimmo
2020-06-23 05:42:57 +0000 UTCThis is an interesting notion, that you can do a decent power factor relatively cheaply, in case energy companies start charging for it... Of course, that's quite the spicy voltage they went with. I hope your video addresses whether this was a necessary result of the power supply or if they could have had both high power factor and less-high voltage...
George Dorn
2020-06-23 04:50:07 +0000 UTCTime for me to be schooled. Isn’t this high voltage switched mode power supply instead of a nice simple rf-friendly linear supply?
Clive
2020-06-23 03:47:39 +0000 UTCAlthough I don't understand the nuances of what you've said, I'm intrigued and eager to see your analysis. And I'm also hoping that this might lead to a build vid.
2020-06-23 03:38:02 +0000 UTC😬
Brooks Andersen
2020-06-23 03:31:35 +0000 UTCThat'll give a nice little nip... :D
Ross Robertson
2020-06-23 03:08:28 +0000 UTCOf course not. Where's the fun in that?
Bill Kerr
2020-06-23 03:05:04 +0000 UTCDo you work in isolation transformer
2020-06-23 03:02:46 +0000 UTCWow, I don't think I've ever seen your meter in the 1000V range.
Michael Dunn
2020-06-23 02:57:25 +0000 UTCneat
God 420
2020-06-23 02:51:15 +0000 UTCI’m looking forward to this schematic, plenty of questions already! Edit: Judging by the PCB I assume this is a brand name device not a eBay special?
WizardTim
2020-06-23 02:39:56 +0000 UTCLooking forward to this teardown. I'm still waiting for my "USB Sterilizer" sticks.
2020-06-23 02:34:47 +0000 UTCRubber pants at the ready.
Jamie
2020-06-23 02:34:44 +0000 UTC
