Well that's not safe - Page 1
Forum section: electronics / general

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 13, 2016, 10:48:51 pm
content: I wanted to experiment with some LED grow lights and indoor germinating/growing of vegetables and other plants. I normally avoid Amazon especially for something where safety matters because most of it is cheap crap from China, but this is kinda a speciality item that you can't really get locally so figured I'd chance it... well then. Check this out:No cap or any kind of protection, I suppose it is most likely current limited, but still. This is a bare circuit board! That is 110 volts DC (measured it) right there, completely exposed. I'm either going to return it or see if I can make it safer. Any suggestions on what kind of covering I can make for it? Once installed it will be more or less out of sight out of mind, and due to that light being hazardous to the eyes I will turn lights off being entering the grow box anyway, but still, it's going to be exposed to high humidity levels.Considering these were not made with any kind of safety in mind, I wonder how likely they are to catch on fire the minute I step out of the house lol. The grow box will probably be designed to have some fire proofing though as it will have lot of lights and there's always the potential for stuff to go wrong even with better quality (still made in china) stuff. Probably use mold resistant drywall for the inside lined with foil or something.

author: Mr.B
author_rank: Unknown
timestamp: January 13, 2016, 10:53:52 pm
content: I have had this kind of crap before too.My solution was to use a thick version of electrical tape to create a wall or mould around the outside of the lamp, extending about 3 or 4mm beyond the front of the LEDs.Then pour clear epoxy into the 'mould'.Once cured, remove the tape.Only downside is you decrease the ability of the LEDs to dissipate heat.You may just have to experiment.

author: wraper
author_rank: Unknown
timestamp: January 13, 2016, 10:59:14 pm
content: LEDs are directly connected to the mains too. There is no proper power supply inside. Usually just rectifier and capacitive or restive dropper. It usually flashes with 2x of the mains frequency too. Dangerous and basically useless as efficiency most likely is worse than fluorescent bulbs have.

author: jwm_
author_rank: Frequent Contributor
timestamp: January 13, 2016, 11:02:13 pm
content: Big clive is the king of finding and calling out these shady lights (and other deadly things from poundland). His videos are quite humorous.https://www.youtube.com/user/bigclivedotcom/videosThat one you have is not as bad because since it has an edison base, it is mostly probably neutral that is exposed (not that that is good) but the bayonet ones will have live exposed on the front half the time!I think my favorite shady thing he has shown is this one with the spring loaded death prongs

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 14, 2016, 01:23:00 am
content: Quote from: wraper on January 13, 2016, 10:59:14 pmHmmm I think we might be heading into teardown territory now.

author: Zero999
author_rank: Super Contributor
timestamp: January 14, 2016, 04:32:05 pm
content: File a return. Then if they just refund you, without wanting it back, tear it down!

author: TechItApart
author_rank: Contributor
timestamp: January 15, 2016, 11:32:35 am
content: Lights which are this dangerous sadly aren't uncommon at all, I've got a couple myself (although I didn't end up using them - too scary).There's a reason the Philips (and other good brand) GU10s and other LED lamps are >$10 each!

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 15, 2016, 07:27:15 pm
content: I saw some other videos of very similar lights, I am wondering if these are basic parts spun out in China and people are just cobbing them together and selling them. There's no name brand or anything.Sadly there does not seen to be any other way to get grow lights, it's basically Ebay or Amazon. Normal stores probably don't make them easily obtainable due to pot growers.Wont bother returning as if they do ask for it, it will probably cost me more to ship than it did to pay for it. So I'll probably take one apart later and see what kind of PSU is in there. If the PSU checks out, I might just epoxy or otherwise cover it somehow as suggested.What I find odd is why don't they just put the LEDs in parallel and have like 3v coming out. Then it does not really matter as much if it's exposed as long as the 3v is also current limited.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: January 15, 2016, 07:39:24 pm
content: Quote from: Red Squirrel on January 15, 2016, 07:27:15 pmUnfortunately that's where you find the good grow lights. Look up your localreputablehydroponics and/or indoor growing specialists.

author: helius
author_rank: Super Contributor
timestamp: January 15, 2016, 08:03:34 pm
content: Quote from: Red Squirrel on January 15, 2016, 07:27:15 pmTo convert mains to 3VDC requires an isolated switching supply with transformers. That is more components that need to be bought in, and made to fit in the lamp base. 120VDC series strings only require a rectifier and some smoothing capacitors.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 16, 2016, 12:47:24 am
content: Quote from: Mechanical Menace on January 15, 2016, 07:39:24 pmYeah none of that here unfortunately.I just tried to take one apart but it looks like it would be hard to do without breaking it, so decided to analyse it from the outside, I can confirm that there is not much as far as a filtering cap:It's also not an isolated supply, those voltages are tested without scope's ground probe connected, so it's relative to line neutral. I'm guessing it's some kind of centre tapped psu, ch1 is connected to one terminal and ch2 is connected to other terminal. (on same side of bulb, so for one string of leds)50ish volts from ether terminal to neutral, with one being negative. If I test voltage between both sides of the bulb (one negative and one positive) I get about 86 volts, which is rather interesting. Between two negatives or two positives I get a few hundred miliamp, which I presume is some kind of phantom voltage. So I'm almost thinking there might be two small PSUs instead of one larger one. Using the word PSU very loosely here.Surprisingly the wattage seems about right. I was getting around 0.1 amps from the wall which comes up to 12watts. It's a 10w bulb, so taking conversion losses into account it may very well be 10w of output (light/heat). Though I was using a (true RMS) clamp meter and not an inline meter so not sure how accurate that is for low amperages.

author: Zero999
author_rank: Super Contributor
timestamp: January 16, 2016, 05:57:57 pm
content: It's probably just a bridge rectifier with a capacitive ballast.Just because the current is 0.1A, it doesn't mean the power is really 12W. If it's a capacitive ballast then the power factor will be much less than unity so the real power will be much less than 12VA.I've got some very cheap LED bulbs which are supposed to be 3W but they're really around 1W to 1.5W and the current would've been around 40mA to 50mA, giving an apparent power of around 10VA. I didn't measure the power or current but estimated these figures, after I reverse engineered the circuit.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 16, 2016, 06:54:26 pm
content: Wont a true RMS meter give me the real power though?

author: ajb
author_rank: Super Contributor
timestamp: January 16, 2016, 08:14:54 pm
content: Quote from: Red Squirrel on January 16, 2016, 06:54:26 pmOnly if you're actually measuring power. You can't just multiply RMS current by RMS voltage and expect to get an accurate power measurement; you have to multiply the current measured at one instant by the voltage measured at the same instant to get actual instantaneous power--do that through the whole AC cycle and take the average to get the total actual power.

author: wraper
author_rank: Unknown
timestamp: January 16, 2016, 08:29:37 pm
content: Quote from: Red Squirrel on January 16, 2016, 12:47:24 amThis crap doesn't seem to even have a full bridge rectifier. Point your phone or some other camera on it, or just try to take a shot in the room lit only by this bulb. You should see how nice it is.

author: chris_leyson
author_rank: Super Contributor
timestamp: January 16, 2016, 09:13:28 pm
content: I was watching BigClive teardown somthing similar the other evening,.Fanny FlambeauxBut seriously, I've only just started to watch BigClives videos recently, and I'm shocked, sorry no pun intended, scary, obviously import controls are a myth then. Colleague of mine been fixing clown 50W LED lights, not thermally bonded, so he had to replace the LED modules and bond them down properly. Heatsinking is a joke as well, it doesn't distribute the heat to the outside only the middle gets hot. The heatsink it's too thin under the LED module, thereby saving on whatever cheap arse shit Chinese crap metal they cast it with.Caveat Emptor so it would seem, so who is liable if this shit kills someone, is it Ebay, Amazon etc.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 16, 2016, 09:48:15 pm
content: Yeah been watching his channel too, some of the stuff that comes out of China is scary. Wait til TPP passes it will be even worse as even if other countries want to regulate stuff they wont be allowed to.I decided to try a bit harder to see if I could pop the board out, and to my surprise, it literally, popped out! So a few teardown pics:The board has some kind of aluminium backing to dissipate heat so that's good at least.I'm not sure what those red things are, some kind of capacitor? Says 474j 250v on it. Those electrolytics are in fact filter caps, but obviously arn't big enough considering the wave form. They're 4.7 uf, rated at 400v. I'd be tempted to look to see if I can find some higher rating ones and swap them out.

author: wraper
author_rank: Unknown
timestamp: January 16, 2016, 10:08:16 pm
content: Actually I have now reread your postQuoteSo those waveforms are just incorrectly measured, therefore 60Hz pulses. On the LEDs themselves there will be more or less DC voltage with some ripple. Those red caps are 0.47uf film capacitors for capacitive dropper. Actually it is better that expected, as at least won't be destroying your eyes with constant blinking. But nonetheless it doesn't make it a tad safer at all. On top of that no fuses at all. If the red cap happens to become short, there should be some special effects. Live and neutral are very closely located too, just a tiny gap between the 2 pads with wires soldered in the center (remember, no fuses). Actually seem like that was a single copper plane separated with V-groove, they just didn't separate those 2 PCBs when separating a whole a panel.

author: Zero999
author_rank: Super Contributor
timestamp: January 16, 2016, 11:20:41 pm
content: The schematic will look something like this:EDIT:I forgot to mention there are two of the above.

author: amyk
author_rank: Super Contributor
timestamp: January 17, 2016, 12:11:30 am
content: Quote from: wraper on January 16, 2016, 10:08:16 pmBigClive did put 240V mains across one of those huge LEDs, and not much happened. The bond wires just acted as fuses.And I'm not convinced it's that unsafe, as you wouldn't touch an incandescent bulb while it's on either... unless it's for 240V input, in which case the 250V cap is far too low.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2016, 12:56:31 am
content: If someone touches a hot incandescent lamp they receive a nasty burn and that's it. If they touch a dangerous, cheap, Chinese LED lamp, they may get more than just a burn. Another thing is, this crappy LED lamp could fail, then the user may think it's off and safe to touch.

author: wraper
author_rank: Unknown
timestamp: January 17, 2016, 01:03:58 am
content: Quote from: amyk on January 17, 2016, 12:11:30 amAnd what if the rectifier goes short too?QuotePff, easily. Turn it on so you can see it in dark room, start unscrewing (have done that and have seen a lot of people doing this). Or you just don't know if the switch is on or off position if there is no working bulb. Or thirdly, switch can be installed on the neutral wire easily.

author: jwm_
author_rank: Frequent Contributor
timestamp: January 17, 2016, 02:48:39 am
content: Quote from: wraper on January 17, 2016, 01:03:58 amI learned the other day that half my house is wired with everything (ground, hot, neutral) in the same neutral colored wire. I guess whoever was wiring it ran out of the proper colors and had a huge reel of neutral to use up or something. made it interesting when I opened the wall looking for hot and was like... hrm?Thankfully, the lights and sockets are actually wired with hot on the correct side, so they paid attention when installing them (or a previous tenant went through and fixed them or something)

author: Planobilly
author_rank: Regular Contributor
timestamp: January 17, 2016, 04:34:37 am
content: This may not be safe......lolhttps://youtu.be/CwhwWeeDqKQThis came to me in a cardboard box, no information at all. I am starting to really like electronics repair!!An yep, it ain't very safe...lolCheers,Billy

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 17, 2016, 05:07:56 am
content: Old radios are pretty neat. You just have to advise the power company whenever you turn it on so they can fire up an extra generator.

author: Smokey
author_rank: Super Contributor
timestamp: January 17, 2016, 05:24:22 am
content: If your primary concern is safety, which it sounds like it is, then don't buy anything that doesn't have a legit UL cert and don't ever use a product except for the application it was intended. Done. Spend the money and don't worry about it.If you are an engineer, then you can make your own informed decision if spending less money on a product with unknown quality is worth the added danger. If you can't make that decision yourself (with a high degree of confidence), you probably shouldn't be asking people on the internet if applying a roll of electrical tape will keep your house from burning down.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 17, 2016, 06:57:03 am
content: You don't really know if it will be UL approved till you get it though. But it's pretty safe to assume anything from Amazon/Ebay wont be.

author: miguelvp
author_rank: Super Contributor
timestamp: January 17, 2016, 07:06:38 am
content: Quote from: Red Squirrel on January 17, 2016, 06:57:03 amSure it will be UL approved, as in Undertakers' Laboratories, not the Underwriters' one

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 17, 2016, 07:17:35 am
content: Quote from: miguelvp on January 17, 2016, 07:06:38 amAnd when I run it for an hour in a controlled environment and it does not catch on fire, I can just slap a QC passed sticker on it, too.In all seriousness I'll probably end up just using these as is. I might look into bigger filtering caps though so I can reduce the ripple, but I figure as long as I don't touch it while it's on, which will be unlikely as it will be in a closed box, I should be ok. The box will also be insulated to retain heat, and will also need to be built with some basic fire resistance, so probably some kind of foil, which will also help reflect light.

author: Zero999
author_rank: Super Contributor
timestamp: January 18, 2016, 01:27:34 pm
content: You really should return it, even if it's fine for your purposes. It's not right they should be allowed to get away with selling this shit.I didn't bother return the cheap LED lights I bought (even though two of the five had some bad LEDs) but they weren't a safety hazard. I have bought some dangerous LEDs and I returned them.