Do you like saving electricity? Who doesn’t!
Do you have a lot of LED light strips lying around, destined for a project that you never quite got around to? We’re guilty!
Do you have an old DC power adapter? Of course you do.
Do you love soldering? Duh.
Do you have a dead fluorescent light bulb sitting around? Maybe…
If so, here’s a quick and silly guide to making your very own LED light bulb! The result is a bit ghetto we admit, but quite functional. Perhaps it could be improved by adding a glass Christmas bobble to make it look a bit more like a regular light bulb. And if you’re ambitious enough you could throw a microprocessor in there and add wireless control to it as well … but let’s be honest, smart LED light bulbs are getting quite affordable these days. But hey, you’ve got to do something for entertainment!
introducing the DIY light emitting fire hazard
#omg #wtf #danger
sirry lads, but i don’t see any hack here
i mean connecting leds to power supply? really?
i would consider this a hack if there were any actual hacking involved but this simply replicates a thing you can most likely buy cheaper in any store, not to mention that this is just not safe in number of ways
Well, my interpretation is: it’s a joke (ans I laught!). It’s bizarre and dangerous. The ONLY thing I can think is.. “it’s a joke… must be!”. Welcome to the “New Hack a Day”.
What definition of hacking are we using? It evidently isn’t “using parts for something other than their intended purpose to replicate an existing item that you don’t have/are to lazy to get” so I’m not sure what you’re expecting.
in addition to other concerns posted above.. please be ware of the toxic mercury vapor in fluorescent light bulbs!
Professional recycling of a dead bulb might be better for the enviroment than the watts saved by this project.
+1
+1^2
Damn that’s ugly !
Yea, I’ve been taking mercury for my syphilis for years and all the voices in my head say I’m fine!
My question is how to repair a cheapo chinese led bulb which aparently broke down with no apparent fault. How the heck can I troubleshoot the led driver that comes along with it? Is there a tutorial lying around you can point me at? Cheers!
It’s called a multimeter.
I don’t get why people keep rectifying AC current to supply DC to LEDs. LEDs ARE diodes; hence they turn the AC into DC all by themselves. Look at (http://www.circuitstoday.com/mains-operated-led-night-lamp). I built one, but didn’t tie the two strings together and chose the capacitor for 120V. I just let one side light on the positive swing and the other on the negative swing. It works great and needs have no loss in unnecessary components like transformers and bridge rectifiers.
Perhaps persons are willing to sacrifice some power in a dedicated power supply in order to have the LEDs on for 100% duty cycle, thus maximizing light output?
It’s only a couple, well, 4 I suppose, of diodes. It’s not a lot to ask, really. It would sacrifice barely any power, with the advantage of doubling the one time per LED. If the LEDs are only lit half the time, at best you’re getting half the light output. Pretty stupid when you’ve gone to all the trouble and expense of building it, only to have the output halved for the lack of a bridge rectifier.
Also is it really OK to just use a capacitor to split the voltage like that? Simple hacks like that are only done, I thought, for very small power loads where the problems it has aren’t important.
The capacitor doesn’t split the voltage. It limits the current. Line power is 60Hz. You just have to calculate the current limited by the capacitive reactance (impedance) of the capacitor at 60Hz. I used a 0.47 uF cap, which limits the current to what the LEDs can handle – including being WAY below the reverse voltage the LEDs can handle. You do have to make sure the cap is rated for at least 1.5 times the peak line voltage.
Being flashed on 30 times per second, the LEDs are pretty bright. The do reach their full brilliance each time.
Yeah but if you rectified the current, the LEDs would flash 60 times a second! You’d double the light output which would surely be noticeable! It seems a shame to pay so much money for LEDs and then only operate them half the time! It only needs a rectifier!
OR to put it another way, you’d only need half the LEDs, giving you enough for 2 crazy lightbulbs!
Pay so much? I built the circuit with two strings of 25 LEDs. That’s a buck and a half. With one string lit while the other is dark, there is no flicker. I’ve built the circuit. It works. It’s a good minimalist approach.
@Fred: No flicker? Or there’s flicker that our eyes doesn’t notice? I think it might induce eye strain on long periods similar to staring at a computer monitor at 60hz. But hey, I’m no engineer, nor an eye specialist.
One slight problem: LEDs are diodes, but they aren’t particularly good ones and do not like to be reverse-biased. Ask anyone who has watched a string LED Christmas lights fail in very short amount of time.
LEDs work best (and last the longest) powered either by current-limited DC or by a PCM scheme that doesn’t reverse the voltage.
The circuit is current-limited, but by the impedance of the capacitor. Being on 30 times per second is pulsed modulation, which greatly increases the life of the diodes versus 100% on. The LEDs still reach full brilliance. Persistence of vision does the rest. The same current limiting provided by the capacitor’s impedance also reduces the reverse bias potential to that which is way below what the LED’s specs show it can handle.
You’re worried about the lifespan of the LEDs? Seriously!? You’re still only getting half the light output, if you rectify it you can use half as many and have some spare. I don’t know the intimate details of LED lifespans, but I’m not sure you can chop a lifespan into millisecond chunks. For one thing there’ll be more temperature variation with only 30 flashes per second.
Because some of us hate 60/50Hz flicker, that’s why.
The flicker from those 60Hz Christmas tree lights is so bad as to make me almost vomit. I don’t even like following a car that has PWM brake lights, because every time one of us makes a maneuver, I see the trail of strobes flashing around the back of the other car.
Also worthwhile, salvaging old LED backlight strips from broken laptop LCD screens.
These also have a small voltage converter which can be repurposed to run from a 12V battery or DC supply and also has constant current/overtemperature/etc built in.
I have a boxful here, now just trying to figure out what to do with the plastics and metal frames :)
I have a circa 10-yr old 15″ LCD monitor I’d be happy to still use. The problem is it’s got gradually dimmer over the years, presumably it has a fluorescent backlight. I imagine it’s the light tube itself that’s faded, the phosphors presumably. I’m thinking of cracking it open to put some LEDs inside, maybe on stripboard or something. Haven’t really a clue where to start, practically. Is this a thing people have done before?
Failing that, I wonder how hard it is to make a projector? The old overhead transparency ones must be cheap to get hold of. Any links to practical stuff would be helpful!
Using LEDs, I repaired a laptop with a dead CCFL backlight. There, the problem was complicated by the bit where the backlight runs directly off battery voltage (3 LiIon) or power supply voltage (18V), so it required a more complicated power supply. (By the time I realized this — oops, measure twice, cut once — I only had accounted for the highest voltage and thus it only was lit when plugged in)
In a desktop monitor, the only tricky part will be the amount of light blocked by the screen; you’ll need a surprisingly large amount of power to look good.
It’s only about @20 for a set of lamps for the display. There are many places that sell the. Installing LEDs in a florescent display would be a pain and you would end up loosing brightness control unless you went through heroic efforts to make a controller for it. It’s just not worth it.
I was thinking that, stuff like the existing lamp will give even output, but I’d need some great diffusion or a million LEDS to avoid a polka-dot monitor. If it’s only 20 quid, that’s different! I’ll look into a new light then, ta.
It just occurred to me, at the time, that there’s plenty of LED backlights nowadays, how hard can it be? Ok, hard!
I’ve made diffuser schemes ranging from sandblasted glass or plastics` with random success for LCD backlights. Some folks have solvent welded LED’s to sanded plastic or edge drilled thick sanded sheets thence solvent welded diodes into the sheet.
As for the crudity of self-rectification for diodes- YES- it shortens light life!
YES- it flickers like hell and annoys sensitive people…
Same with the Capacitive power hacks as opposed to “Proper” drivers.
But sometimes the brutal fugly solder the handful of diodes salvaged from dead tree light strings etc into a wiry furbal of *LIGHT* that just plugs in& WORKS is the Final Answer.
Good Enough-IS…
@Fred Frankenletter
LEDs in such set up only light up half time, so you need 2x to produce the same light. Cost efficiency of LEDs as rectifier is horrific.
I got a bag of one hundred 20,000 MCD LEDs from fleaBay for 2.99 including shipping. I’d hardly call that horrific cost.
120 VAC rms = 170 VAC peak to peak
170V / 3.2V white LED forward voltage = 54 white LED’s in series
Put a fuse in series and an MOV in parallel with the 54 LED’s….
No need for a rectifier / DC converter, and/or step down transformer…
And sit back and enjoy the flickering…
They don’t flicker at all. Persistence of vision can’t detect it. Also, when one half of the LEDs are dark, the other half is lit. It really is pretty bright and steady. Plus, it’s sorta like PWM, which greatly increases the life of the LEDs versus on all the time.
It’s awfully easy to see 60Hz flicker in LED xmas lights with their duty cycle of something like 25%. It shows up any time your eyes move at all.
Also, those LED strands are actually driven to just about hit their RMS max. You’re not extending their lifetime by driving them at 400% power for 25% of the time.
Were it 120Hz, with the LEDs driven by a full-wave rectifier, and I’d think you’d have a point.
Those Christmas lights are flickering at 30Hz, because you’re only using half the 60Hz wave. At 60Hz you probably wouldn’t notice it.
No, I know exactly what I’m talking about, and have used tools (high speed video, light sensor and oscilloscope) to verify that they are flickering at 60Hz. Each strand flickers at 60 Hz, and each strand is 180° out of phase with the other.
30Hz I can see directly. 60 Hz I can see whenever I saccade.
Instructions were not clear, dick stuck in light socket
possibly the best comment here
Built this. When I plugged it in it tried to assimilate me.
For my car I
Took Globes my cars globes de-soldered the the bayonet shield from the globes put on wire
Then
De-soldered SMD Super brights from some strips only put 3 rows of 4 LEDS cut some plastic glued leds to plastic joined up pushed in plastic stand into Shield.
Car lights up very well can see things on the floor at night now.
As for this supposed Hack listed what’s the point of trying to emulate the globe with a box type set of LEDS, why not create a dense panel of Leds in a flat form to fit inside the light diffuser. Surely this would provide a greater area of light than a sad little box.
I do basicly the same thing but it runs off the 12.V rail of one of the computers. I use 4 white L.E.D.’s in series. But also other colors (I favor orange and yellow because the white has a bluish hue that I don’t like which gets worse as the L.E.D.’s age)
As a guard against shorts I put a 10 ohm 2 Watt flameproof resistor in series at the computer – this will limit the current to an amp or so, and the resistor won’t smell much and will usually survive long enough to correct the short.