Instructables

{THE LED LIGHTBULB}

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Picture of {THE LED LIGHTBULB}
With energy at shortage, we strive to conserve. Although we attempt to buy the greenest electronics and turn them off as much as we can, we still find ourselves with those energy wasting incandescent bulbs or those mercury infested CFLs. The immediate solution that comes to mind to switch to LED light bulbs, which is then stricken down by the fact that LED spots are still at an extremely high price, making it cost a fortune to convert over all of your existing fixtures to this technology. But this is instructables, so we can make our own! What we will end up with is one of the most energy efficient light bulbs you have ever had in your midst, made at a ridiculously low cost. This will save you $100s of dollars throughout the lifetime of the bulb; so feel free to write me a check for the calculated amount!
 
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Step 1: [SUPPLIES]

Picture of [SUPPLIES]
With LEDs at such high costs, you must know a tremendous supplier. I ordered most of my supplies from two main sources, LED Shoppe and All Electronics. I have found these suppliers to be the cheapest and most reliable. I ordered a large quantity of supplies, since I am going to make several bulbs of various sizes, which made the supplies cheaper. Below are the list of things I needed for this project:

LEDs - I used 5mm LEDs. You can change the type of LEDs as long as you augment the calculations accordingly.
Bridge Rectifier - Converts AC to DC.
Perfboard - The size of perfboard you buy will depend on the size of light bulb you wish to create.
Soldering Iron and Accessories - The cheapest of soldering irons will do.
Base Plug - This product has a normal bulb's base at one end and a normal household outlet on the other. Your local hardware store will most definitely have some.
Cable Ties - The question here is not if you have them, but, rather, how many hundred of them do you have.
Cardboard - This is the main support piece for all the component of the bulb.
Wax Paper - I used a silicon cookie sheet (that rolled up blue thing) instead. You can use practically anything that has a high temperature tolerance and doesn't conduct electricity, but I have found these to be the best materials for the job.
Drill and Small Bit - I used a 1/8" drill bit.
X-ACTO Knife and Whole Puncher - These items will be used to prep the insulation.
20AWG Wire and PVC Pipe - These are required to connect the bulb's base to the rest of the assembly.
Multimeter - I always keep my multimeter handy in order to check conductivity and make sure there are no shorts.
seiki_h1 year ago
Hello, I have two questions:
1. What does the 1.4 value calculation?
2. Can I use size rectifier 2A 400V instead of 400V 1.5A?

grateful
rmd65021 year ago
I think you should add a low-resistance (1Ω or so) 3W resistor to help regulate the current for the LEDs. Problem is they all have different specs, so some LEDs will drop less voltage, leaving too much for others - the resistor will help limit the current. Better still, a LED current regulator chip.
LGProspects2 years ago
So I did the build I am in the US so based everything off here. 5MM leds, 3.0-3.2 FV. Did the math and got 55 LED's needed. During the check it came back as 2.8. So I figured it was UNDER voltage at 55 so went for it.


I did everything following your diagram and it was a nice glitter show for a microsecond. It appears about 10 LED's are dead.

What did I do wrong?

Lance
ogled0022 years ago
Can anyone tell me if I can go up to 7 series at 46 LEDs each, with the same one size bridge rectifier that is used in this project or do I need to go bigger on the bridge rectifier?
jasonm6212 years ago
Can you insulate your circut with something like that paint on electrical tape stuff or hot glue? Just for ease of construction by glueing stuff together rather than zip ties... Just a thought... Just wondering the safety of insulating with hot glue cause its easy, cheap, and readily available. Not to mention one less step of assembly... Any thoughts?
Speedmite5 years ago
Nice idea and instructable. Im not good at calculations though..... I was just wondering if this is legal or not. I personally like the incandescent bulbs. florescent bulbs are fine, except the mercury. Im not to big on the white leds because the look cold like somone died unlike the freindly yellowish light of incandesent. And yellow leds, are well, yellow. But nice Idea. I like the effort for cleaner ways that many people lack.
aandre (author)  Speedmite5 years ago
umm legal....in what way?
Well, I would think that you cant just plug in any science creation, hoping that it works and doesn't cause something crazy to happen. I mean, this is 120v your dealing with. If you soldered something wrong you could burn a house down or cause an explosion. Im sorry if you take this in a negative way, but I'm more cautious than many people. And no, I dont have any affiliation with the law. Just my best guess that it might not be legal.
I personally don't see what's wrong with it, there should most likely be precautions that one must abide when doing this, as with anything, but with today's modern technology almost everything has a power trip of some sort, so if it shorted out or screwed up some how it would probably turn off. Just wondering, where do you live? I'd like to do a little research if I can about the laws and regulations about this.
I completely forgot about fuses and such. It justs leaves me with the "what if?" question in my head.
Fair enough, better to be overly cautious then not cautious enough. That's why I cut my finger nail in half, burst my ear drums, burnt my fingers and left a circular hole in my finger, all within 2 seconds. Never, ever be stupid with party poppers...
How did you manage that? My freind stuck his hand on a hot stove for 5 seconds to prove he was a man. I wasnt there, but i doubt it was five seconds and he did go to er. and he has scars. But it proves nothing and I recommend you dont do that. It only proved idiocy.
I can't find the instructable at the moment, but it shows how to use the small amount of explosive in a party popper, inserting it into a pen barrel in one end and a some thing in the other (as ammunition) and pulling the string to fire. I cut my finger nail in half cutting an eraser in half for amo, burnt my finger from the explosion, burst my ear drums from the bang and the circular scar from the back of the pen shooting backwards. I'm just glad my parents didn't hear it, otherwise I may have sustained other injuries...
=) Speaking of gunpowder that reminds me of when I was trying to get the powder out of those plastic rings for cap guns with a pair of scissors. I made a cap go off when i stabbed it, and those things shoot fire. Singed some hair on my hand. Scared the crap out of me....
XDDD
seeing how you guys are talking about stupid things you have done with fire im going to tell my story: So i saw an instructable on how to make flamming fireballs out of cloth and grill starter fluid or whatever its called. so i made them just fine outside and wanted to make more. But i had to use the restroom as in like number 2 if you know what that meens. and if you knew me you would know that i do anything in the bathroom just like i would do anything anywhere, so i made some in the bathrrom. i was stupid enough to try it out to so i put the fluid on the cotton balls and without me relising a lot had gotten on the floor, im guessing it was the fumes. so when i look one of the balls it had started to burn my hand so i dropped it. then BOOM!!! my pants, shoes, my little sisters jeans had all caught on fire. I was still sitting on the toilet saying "WTF!" and then i just stood up and took my pants off, threw them outside and beat them to put the fire out and had completely forgot about everything else in the bathroom. so i went back to wipe and i saw my sisters pants burning up in flames so i took those trying not to burn myself and dowsed them in the house right outside our front door and then hid them so my parants wouldnt fine them. and my shoes, they just went out by themselves. So thats my story, lol my parants still dont know.
You are damn lucky ! You could have burned yourself to the point of needing plastic surgery (grafts from your bum). Why are you trying to self-destruct? Go outside and play with fire! Can I take out an insurance policy on you? I would love to retire rich!
Still can't stop myself from laughing and I read it over a minute ago, seriously, how can you get so unlucky!?!?!?!

I made those fireballs but I used metho and you couldn't hold it but you could throw it at people if you didn't grab it for more than about half a second.

One thing I can say for you, may your parents never, ever, ever, ever, ever find out what happened.
I knew my parents heard the bang, but i dont think they knew I was blowing myself up.
My parents have learned that if there's a bang, they should probably check what I'm doing...
The usually just tell me " Your going to ________ doing that and it will hurt" and then they leave me alone. And 95% of the time im fine. No er visits yet.... The ____ is like a fill in the blank thing. Like fire is burn, homemade turbo fan is get hit, ect.....
Turbo jet is burn and hit? :D
No, I stuck my finger in it.
Not a good Idea.
Ow!!! I want to make it now.
It wasnt actually a jet, its just easyer to say and a lot cooler. It was a really nice electric engine from an erector set (google it if you dont know what it is) and I attached a special part which allowed me to build stuff on that can spin. So I attached the two longest beams on and turn it on. It started to spin so fast, It turned invisible, and I had an instant of stupidity and forgot about it and tried to reach through. I didnt get too far, only half a fingernail. I cant wait to buy rc helicopter blades!!!!!!
Then its a turbo prop.
I would take a picture and post it but I unfortunatly dont have a usb cable for my phone.... and I dont want spend my mony on it though.......maybe Christmas......
It felt wonderful too..... It made a blood blister under my nail and on the tip of my finger and the pressure under my fingernail really hurt, so I had to pop it right befor dinner and I ate with my other hand cause my finger still hurt and was still draining a little. And then the next morning I looked at my nail and it felt just fine, just a little sore when pressed, but the skin under my nail had pulled away halfway back. Its almost done healing now, a month and a half later. as in the skin has almost reconnected fully. IT WAS SOOOOO WORTH IT!!!!!!!!!!!
Funky wording, I call it lighter fluid but there a heaps of words for it, and that is absolutely HILARIOUS!!!!
I don't know how to put this. You're wrong. It's not illiegal. It's just not UL listed. The design is good. This isn't far from how the factories do it. If "you" don't understand the concepts involved, that doesn't make it wrong. If you don't know how to test a circuit to know how it's safe, then don't do it. If you'd like to know how.... this is definitely a place to ask.
Yes, I just found out that it is completely legal. Saw some at walmart and they have a patent pending, but this is the same general idea, not exactly the same.
Good to hear, thanks for telling!
TotalLED4 years ago
You can also use a PC power supply to run a number of LED's bulbs Supply volts @ 5vdc...low side output. I have LED's thru-out the hole house using one 850 watt PC supply. Bypassing standard AC voltage to the use of one AC outlet....3 years running with zero troubles.
xana TotalLED3 years ago
this could work, do you have an instructable on that .
hi aandre, Afew days ago I bought all the material that you said in this instructable, I want to make the small one. My problem is how to assemble all the leds and the rectifiers...!!! could you help with this, do you have more pictures for the part of the rectifiers?? Pictures helps a lot!! more than text !!...so I appreciate if you could send some photos... Im doing a proyect for a school. thanks !!
junits154 years ago
its kindof im practical but nice still
Kryptonite5 years ago
Wow great instructable! Just wondering though (please forgive me, I'm not as well learned in the field of household electronics as I probably should be) but how does this save energy? I don't know, but isn't the same amount of energy put into it?

I'm not trying to be negative, and I hope with some explanation I won't be "kept in the dark" for any longer...

*cough* bad pun *cough*
This saves energy because LEDs use fewer watts to produce the same amount of light as a regular (incandescent) bulb. (Watts is the amount of energy used over time, so each minute that this is on it uses fewer total joules than each minute that an incandescent is on.) This is because LEDs produce light much more efficiently than incandescent bulbs. So this draws less energy than a regular bulb from your wall socket. Even though the socket always has the same number of volts, it will only give the amount of energy being drawn by the appliance. So, for instance, your TV draws a lot more energy from the wall (and from the power company) than your smoke detector. So this gives the same amount of light as a regular bulb, but draws less energy from the power company to do so.
don't smoke detectors usually run on batteries? i understand what you mean though
 Not all of them, more and more places are putting battery backed detectors that run off the grid power (the battery being there for power outage). That way it is less likely you will forget to change the battery and have a worthless hunk of plastic on the wall/ceiling. 
All Hardwired Smoke Detectors and interconnected with each other. You have to run a 3 Wire to each smoke Detector. The black one (hot) the white one ( neutral) and the red one is for the communication between each Smoke Detector. The reason for that is. If one Smoke Detector makes an alarm , all other Smokes make an Alarm to. Only to the first Smoke you run a two Wire. The Battery is is for the Alarm in each unit. If the the Power is cut of, each Smoke will make a beeping sound every so often. The Battery is not really for a Power outage. By the way, that is one of the best investments in your live . ( Your kids play with a lighter start a fire and you sleep. So when the Smoke in the Kids rooms goes on, you have an Alarm in every other room that got a Smoke.)
Not ALL hardwired detectors are interconnected like in my last residence. It ran off either the wiring or battery. I learned this in attempts to not to scare everyone when cooking steaks.
If they are proper installed by a professional Electrician, they would be all interconnected. And for sure you would not have Hardwired and Battery operated mixed together. That's so wrong. You should also, never, ever hardwire different Brand/Types of Smokes together.
Using any definite will get you in trouble. Accept that there is more out there to skin a cat. I have plenty of grid based products with battery back ups (both rechargeable and not). These were builtin when the building was constructed, I first pulled battery, alarm continued, replaced battery pulled hard wire, alarm continued, pulled both and nothing, and no one else ended up being aware surprisingly. So if it wasn't a smoke detecotr and just coincidentally went off when smoke was present you are right, if not you are probably just mostly correct with exceptions, as there almost always are.
All Hardwired Smoke Detectors are interconnected
Ahhh, thank you for filling that large blank space behind my eyes. I believed that the same amount of electricity was put into the appliance no matter how much it needed, but the appliance would not take as much in depending on how much it needed. Thank you for your very descriptive response.
Hmm... if one LED dies in te first series.. all will turn off?
meissler5 years ago
Could you just use any 12V power chord (like a charger for a computer or something) and hook the +/- ends up to the right areas? Of course use resistors too. Would that work or no, not really?
 Yes, it would. You could also try to find a wallwart to some broken or lost electronic device and use that. A DC power supply would bypass the the rectifier as well. It would be more likely to last longer (read: fewer parts = fewer issues, generally but not always). Hopefully whatever power supply you find has some power regulation going on so it would be less likely to spike and such.

Long story short: yes, and for the most part I would recommend it, especially if you go with 12v you could easily convert it to an off grid solar project as well, since smaller projects like that stick with 12v.
Is it okay if the 20awg wire is rated for automobiles?
lmarka4 years ago
Hi! Is it possible to add a PWM controller (maybe adding a capacitor after the rectifier to run the whole thing at DC) to this project??
Everything I found so far is for low voltage, don't know if it would be as simple as slapping in the Mosfet in series with the LEDs.
ramedia4 years ago
For those who don't have the technical chops,  I found these for $10 each (2 for $20).  They produce the equivilant of a 20watt bulb's light.  http://www.overstock.com/Home-Garden/Grip-30-LED-Light-Bulbs-Set-of-2/3339673/product.html?cid=123620&fp=F&ci_src=14110944&ci_sku=11432846
Highjump444 years ago
 How fast was the shipping bcz im in the US and I just found out its coming from Hong Kong
trekman4 years ago
I built 2 of the small LED light bulbs following the Instructable. I used the same rectifier and had 46 LEDs in series. I made these as a night light and they worked fine but only for a couple of weeks. I also used the LED array wizard but it wanted a 2.2K resistor added to the circuit. I tried the resistor but it dims the LED about 25%. What can I do to make these last longer? Thanks
Teleran4 years ago
I gave up on the Idea of using a TI783 Regulator, because many things need to be done to keep the thing working. I kept on measuring the Line Voltage for Max Avg and Min, it goes from 136 Volts AC down to 118 Volts AC. I measured the outputs on my inverters, and it is a nice constant 119 Volts AC. So now all the 46 Led Lights that I made work perfectly, on Batteries, not using Hydro, giving a nice constant light with no flickering at all! Thank you for making this project available. Now it really will save me some money in the long run. Teleran.
Questions: in this series crt, 110-125Vdc/1.5A is initially applied to 1st Led (rated at 3.2-3.8Vdc/30mA, doesn't this cause damage to the Led? Thanks.
Teleran5 years ago
I measured the line Voltage here for a few days, and it goes from 119 VAC to 133 VAC. So I'm thinking now or making a Regulator which can be plugged into a Surge protected outlet, which prevents the LEDS from damage, and then adjusting the regulator to about the Voltage that 46 LEDS with a Forward Voltage of 3.4 volts DC to 3.6 Volts DC. This way the LED Arrays are immune to AC Voltage fluctuations, and Surges, and will even stay on during minor Brown Outs, without flickering, or turning off, having a nice steady output. Here in the Third World LED Projects cost more than just a few bucks, and it is nice to be able to have efficient lighting, running on AC or hydro, that last for many years, instead of flickering when the voltage drops by more than seven volts AC, or turning off when the voltage increases to more than what it can take. I've been looking at low parts count, IC regulators that might be able to work these LED Lights. In the past I made DC operated LED Lights replacing 450 Watts of Hydro lights with 24 watts of LED lights. Even after 4 years they are still working! Teleran
Teleran5 years ago
Hi: Lolzertank:

I used 5 mm Ultra Bright White LEDS. VF is in the range of 3.4 Volts to 3.6 Volts. The Hydro here, is in the range of 115 +/- 5 Volts AC 60 Hz. It's the Country, things go up and down. The Math given did not account for numbers on the other side of the decimal point. So 46.05263 was rounded off to 46 LEDS for a Voltage of 125 Volts AC or 175 Volts DC..

Using the Math given 120 Volts X 1.4 = 168 Volts DC.
168 Volts DC/3.6 VF Max = 46.6666 # LEDS Do we round off to 47 or leave it at 46?

Check
110 X 1.4 = 154 Volts DC
154 Volts DC/47 # LEDS = 3.27 Volts this is lower than 3.4 Volts VF Min.

The AC Voltage range it will work in is then:

47 # LEDS x 3.4 VF Min = 159.79 Volts DC/1.4 = 114.14 Volts AC Min

47 # LEDS x 3.6 VF MAX = 169.2 Volts DC/1.4 = 120.857 Volts AC Max

this is a 6.717 Volts AC Variation.

I used 46 LEDS

46 # LEDS x 3.4 VF Min = 156.4 Volts DC/1.4 = 111.7 Volts AC Min

46 # LEDS x 3.6 VF Max = 165.6 Volts DC/1.4 = 118.28 Volts AC Max

I made 9 all the same type with 46 LEDS in series, powered by a Bridge Rectifier. No Epoxy this time. 2 failed after 2 seconds of power on. The rest worked Ok so far.

I'll monitor the line voltage, for maximum and minimum spikes for a while, see what the AC voltage variation actually is. Might have to fix this with a resistor, or more LEDS or something??

Teleran

Teleran5 years ago
(removed by author or community request)
Does your line voltage tend to spike a lot? Also, if your LEDs have a forward voltage below 3.8V, (they probably do), you'll need a couple more LEDs in series. You're not going to get 100,000 hours out of them even in the best conditions. 5mm LEDs' heatsinking is so poor that only the best 5mm LEDs (Nichia, Cree) will survive about 1000 hours before the phosphor or the die failing. Even if it survives that, epoxy on the LEDs will turn brown in much less than 100,000 hours.
barligea5 years ago
how cool is that ...let there be light...the efficient way... great post!
222fbj5 years ago
Good Post.
FYI - prefab LED-PCboards are available (at extra cost of ~$4)
see http://c-leds.com/shop/product_info.php?cPath=26&products_id=78
pcb1.jpg
whats wrong with "harvesting" led's from deceased autos in th' scrapyard ang using a diode bridge rectifier from a old automotive alternater ? recycling and savin' money at both ends of th' job !!!
I would recommend putting a 0.5 amp fuse in the line.
NachoMahma5 years ago
. Excellent iBle! . I am concerned about the use of waxed paper and cardboard. Sounds like a fire hazard to me. . There's a good chance that a problem in the device that will generate a lot of heat will not trip the house wiring fuse/circuit breaker. For home use, a fuse would be a good idea.
Cardboard is very common in electrical appliances as a divider (look inside a light fixture the next time you change a bulb and wax paper is most commonly used in baking where an oven gets over 350 -500 degrees and the wax paper is fine. Besides LED generate almost no heat which is why they last so long. I don't see a problem if the builder has a solid understanding of the subject.
. It's not the LEDs I'm worried about, it's the rectifier. . "Electrical" cardboard is impregnated with flame-retardants. . Too lazy to look up the facts on waxed paper, but I do know that once it starts burning, it burns VERY well. . A lot of ppl that may try this may not have a solid understanding. . . It's still a very good iBle, just needed a few warnings for newbs.
I personally agree with you one hundred percent. Just a question, that's not really related, but what caused one to put a full stop in front of each sentence? Why didn't I think of that?
. Preserves paragraph indent - most BBSs strip "extra" spaces.
Cool, and smart.
I am not sure LED lighting, with off the shelf LEDs IS any more energy efficient than CFL yet is it ? Steve
It is, by a factor of like 10. A 13w CFL will output similar amounts of light as a 60W light bulb. These LED lights will consume maybe 1w of electricity, and output 100w of light if properly constructed. Not to mention that the LED's will outlast the CFL by years, and they don't get warm and fail in recessed fixtures like CFL's do. And the Mercury is bad too. :P
Ahh, no. These LEDs can put out 1.5 lumens each tops. If you use 184 of them as suggested for the "large" array, that comes out to be about 300 lumens. As the author has noted, the power consumed by these 184 LEDs is >10W. That turns out to be less than 30 lumens per Watt, which is about twice as good as a 100W incandescent bulb. For comparison, a CFL is in the 60-80 lumens per watt range. The best available LEDs are in the 100 lumens per watt range, with the best warm white LEDs in the 80 lumens per watt range. These efficiencies come through underdriving high quality ($$$), high power LEDs, for example running at <300mA for a 1000mA rated LED. The result is that for truly high efficiency (and long life) you need a larger number of high quality LEDs, running at reduced current. This equates to $$$. For example, using a Cree XRE warm LED driven at 300mA, to get the equivalent of a 100W incandescent at 1600 lumens you would need ~20 Cree LEDs at ~$4 each. Alternatively you could drive the LEDs at 700mA and only need ~12, at the cost of increased thermal load and reduced lifetime. In any case, I hope this has been helpful in showing why LEDs are not ready to replace incandescent, halogen, fluorescent, or CFLs in most residential applications.
I'm interested to know, where do you source all this information!?!
Experience, data sheets, and the miraculous series of tubes known as teh Internets.
:D
In cold climates, incandescents are also good for heating the house - but in environments where you throw the excess heat (low entropy not really useful) away it's not as good. LED is on the forefront of 'becoming' the next gen - and I build these just on the grounds of the no mercury - it defeats the purpose if you have to use lead solder to assemble them though.
You don't have to use lead solder, and lead isn't actually that bad for you unless you shove your schnoz (nose) over it when you're soldering. Plus, another small argument, if it breaks (unlikely?) then at least you don't have to leave your windows open for an hour or so afterwards.
I stand corrected. Your math is sound. I was mistaken at how inefficient LED's were at Watts vs Lumens at this time. How is it then that the flashlights have all turned to LED drivers? Is it that the lower voltage incandescent lights are just absolutely horrible at W/lm output?
LEDs are efficient, just not the answer to all problems on earth. Some of them to be sure, but not all. Flashlights are an app that power LEDs are perfect for. DC power, thus simplified drive electronics. High shock environment, the incandescent bulbs will fail on a good drop. LEDs are much more efficient than the incandescent bulbs, and with the boost circuitry can maintain high light output over a wide range of battery charge. The preceding refers to power LEDs not the cheap radial lead style used in this instructable.
AND leds are already inherently directional - bulbs require an inefficient reflector/lens.
The semiconductor industry would not be happy for me to tell you, but the process of making LEDs is not exactly an environmentally friendly process either..... Mercury is not BTW a cumulative poison, despite its reputation - mammalian biology at least has a pretty effective mechanism for eliminating it. Hg HAS a finite half-life in the body of around a month or so I believe. The dose you get from a broken CFL is unlikely to be an issue unless you make a habit of sniffing a dead tube every day or so.

Steve
It is cumulative in the food chain, though, particularly in shellfish.
gandlof55 years ago
I wonder if adding a few various color LEDs would help balance the color, red orange, yellow, and green. Ever notice that on stage productions they never use a white light; but mix different colored lights to get a "white" light? Might not be room on the small. And you have to recalculate the strings as every color has a different voltage drop.
jessieshop5 years ago
thanks for the money saving idea, where can i buy those LEDS?
aandre (author)  jessieshop5 years ago
I bought my LEDs from www.ledshoppe.com and they cost 5 cents a piece, as opposed to the average 65 cents.
thanks from filipino guy here. just get addicted doing this stuff, better than going out. thanks again
*cough* nerd *cough*

... Me too. High Five!
nert5 years ago
Nice instructable. I like oboist1 suggestion to use leds on both sides of the perf board. maybe add a 2nd rectifier and light leds with the opposite side of the square wave.
MrMike5 years ago
Why bother with a "bridge rectifier" ? But please do include a current limiting resistor or other over current protection device.

The LED's are DIODES. Yes only half of them will be on at any point in time if the strings are wired anode to cathode, but your eyes will not see the blinking .

Since the diodes (LED's) are specified in DC terms i.e. forward voltage drop of 1.8 to 3.8 VDC (IR to UV) it's easier to think in V=IR terms. However the "source" is AC (60 Hz), try to think in terms of reactance and frequency

Try a simple circuit of 2 LED (wired cathode to anode) in series with a .47uF 200V (for 110VAC input) capacitor is series with a 1K resistor (to limit the current into the capacitor if it's switched on near a peak AC cycle). Works great as a power-on indicator.

Buy a "cheap" set of LED Christmas lights and take apart the "blob" in the power line to see what's in there....also a cheap (60 of them for $1) source of LEDs, but with unplated (steel) wires.

I have two more questions.

How do you determine which bridge rectifier to use?

If I understand it correctly, if you have two strands of 46 LEDs in parallel, the positive lead of the first LED in each set connects to one of the rectifier leads, and the negative leads, and the negative leads of the last LED in each set connects to one of the rectifier leads?

thanks =]
aandre (author)  Weissensteinburg5 years ago
That's right. As for bridge rectifiers, I used a 1.5 AMP, 400PIV rectifier. All you have to make sure is that you use less current than the rectifier allows and that your peak inverse voltage (PIV) is more than the actual voltage you will use.
Thanks. And just to be absolutely positive, before i get the stuff, Instead of a base plug, I can just use prongs for direct connection to an outlet, right?
DasBus5 years ago
WOW! Great Instructable! I just may attempt this project. And it's great that so many of the comments posted are helpful too!
RetroTechno5 years ago
This is a very good instructable. There are just a couple of additions that I can suggest to Section 2.
  • In Japan, typical outlet voltage is 100V (sorry I don't have max/min).
  • You might want to describe the RMS to peak conversion in the first equation. It took me a little while to figure out what you were doing.
Also, you might put a fuse in the schematic, just in case there's some construction problems. I could see a lamp going up in flames.... :-o
A fuse? LEDs can only be powered one way, a.k.a you simply cannot short it - or do you mean something else?
Thav Eirinn5 years ago
If the mains connections short or someone touches the bulb or its internals it is a good idea to have the thing fused. It's a fire and safety concern. If you ask UL, you would possibly need TWO protective devices, in the event one fails. I'm not sure if that applies to household electronics, as I work in industrial power.
Eirinn Thav5 years ago
I'm still not sure i get it, the LEDs acts as a diodes so that current can only "flow" in a single direction - shorting an LED "bulb" is simply not possible - you can overheat it though. What could go wrong is + and - touching each other directly or maybe something in the rectifier - in the case of a rectifier and the mains coords yes i agree 100%, but not on the pcb itself. I do agree though that for testing purposes one should -always- use a fuse when connecting to mains. I forgot to say that i like this project btw :)
Thav Eirinn5 years ago
This design pretty much relies on the LED forward drop voltage and series resistance to limit current. Diodes *can* short, so that they will conduct in either direction. This can happen because of surge currents or mismatches in the series diodes, causing one to have higher losses than the rest of the string.

One LED in the string being able to conduct in reverse would not normally be a bad thing (despite losing its light), but its forward voltage and series resistance may drop when it fails short, so then your only method of limiting current is suddenly letting a lot more current through, which only increases the chances that the rest of the LEDs experience excessive heating and fail sooner.

That being said, I don't know how likely these failure events would be. Using the fuse at the connections to the mains would absolutely be the way to go, and I would recommend that for any project, not just for testing.
Eirinn Thav5 years ago
Is this why people traditionally add a resistor to each led instead of where the parallel point start?
If you have a bunch of LEDs in series-parallel, there's a pretty good chance that they won't be exactly matched, so one string may burn brighter than the other. Using a resistor in series with each string (rather than a single resistor) would eliminate that risk. A fuse before the bridge rectifier is essential, since if a rectifier fails, it usually fails short-circuit. I'd also add a transient protection device like a MOV or transzorb to protect from voltage spikes. And, finally, a filter capacitor to reduce or eliminate flicker. I think each instructable should have "Darwin" and "Rube Goldberg" factor ratings assigned by a cabal of qualified experts, based on safety and practicality.
You guys are being too academic about this. You're assuming the circuit is built perfectly. This is a DIY site and there will be many folks with low experience in building circuits who want to do this. The A.C. and the D.C. side are high potential any mistakes could be bad news. And fuses are cheap.
frollard Eirinn5 years ago
leds can fail in a short circuit - causing the voltage for all the others to go up in the series chain. If enough fail, then you've got dangerous voltages going thru the remaining LEDS. Thats where the danger comes in
If you use a capacitor to smooth the rectified DC the AC volts (by rating, ie 110 or 120) should average the same energy as 110vDC - rms is just good so you dont fry your leds. Smoothing is also good so you dont get flicker. I hate flickering lights.
rc jedi5 years ago
nice, with low heat. I just like the color of these led's. cool 'ible.
alzie5 years ago
Something to consider - You would be WELL advised to add a ballast resistor. LEDs are constant voltage devices. Ie. a small increase in voltage will cause a Massive increase in current. A spike on the line will blow out directly connected LEDs. Commercial LED lamps use well behaved behaved ballast electronics to isolate the LEDs from the line, and control the drive current. At the cost of a small efficiency loss, i usually waste about 1/3 of the source voltage. For this app, i would use a 40 led string, with 1.8Kohm 2W power resistor in series. Al D.
chrwei5 years ago
where does the 1.4 value come from in AC MAX X 1.4 = A ?
AC voltage cycles from zero to a peak voltage and back down to zero again. The voltage given is an RMS value, a kind of average, it is not the peak voltage value Multiplying by 1.414 gives a good approximation of what the peak voltage is. By working this out you find the maximum voltage that your led's will be subjected too rather than the average. That way your leds don't blow up on that first AC peak hope that helps, if not I'll try again
so AC MAX is really a MAX average? I know AC voltage fluctuates, but 40% seems excessive
Well its a bit more involved than just a simple average,
RMS stands for Root Mean Squared
The square Root of the Mean value of the integral of the wave Squared

If you were to draw the sine wave on a graph,
you could then find the mean area between the line and the x axis,
finding this area will give you a set of limits which you calculate between,
you use the limits to find the area of the integral squared,
then square root the whole thing.

if you work through the proof for the general case you can skip the above calculations as it comes to a general formula.

RMS voltage = peak voltage x 1 / root 2

where 1/root 2 =0.707 (rounded)

and to go back

peak voltage (AC MAX) = RMS voltage x ( root 2 )

where root 2 = 1.414 (rounded)

So AC MAX is the actual peak voltage (maximum voltage) at the crest of the waveform.
The peak voltage is only there for the smallest fraction a second, but in the case of the instructable above would be long enough to pop your led's of you didn't take it into account.

The RMS value comes into play when calculating things like power usage, where you can drop it into equations like ohms law as if it were DC

Hopefully that makes it a bit clearer :) much further I'll have to get my maths book out don't think I'll be able to do it from memory anymore
I think I see now, well after looking up Root Mean Squared. the short answer is: 1.4 = sqrt(2)

the longer answer, the AC MAX of 120 is the RMS max, not the actual AC peak, which is more like 170V but only for a tiny fraction of 1/60th of a second. (since AC goes from 170 to 0 to -170 to 0 to 170 in 1/60th of a second). the formula being Vpeak = Vrms * sqrt(2) and the square root of 2 is about 1.4.
if anyone wants to know where that comes from, http://en.wikipedia.org/wiki/Root_mean_square#Average_electrical_power
ancahe5 years ago
Hello! Would love to build one but I live in a 230V country.. and none of the wizards go up to that voltage. If I use your calculations I get: 97 LEDs per Row. And ehm what about resistors? Don't you need any of those? I would like to use 200 Leds for a lamp.. well 2x97 is quite close ;) Thanks for any hints and advices.. -andreas
finfan75 years ago
You do realise you could just buy an LED lightbulb for this price.
ootsae5 years ago
I loved it, Thanx for nice instrucable.
fozzy135 years ago
Great job : )... I personally have had this exact idea/schematic in my head for at least 4 months but didn't have the money to buy enough white LEDs..
darnold1005 years ago
LED Supplies. Ok, I'll let you all in on a little secret of mine for cheap LEDS. But If ya mess with my supply when I need it I'll be lookin ya up. I've used them for accent lights under my stair treads (dimable) and am starting to use them in furniture. If you are handy and know a little electronics, pilfer the after christmas sales on LED Christmas lights. If memory serves me I paid $1.50 for a 60 string. Nice bright colors, rectification included, if you want to split up to use individual LEDS just modify the resistor value and the option to use a battery
DANTOSAR5 years ago
hej i have a question from where you have 1000 led which site an you give me please thanks dantosar
wirecutter5 years ago
GOOD Ideas. But the thing about LED's is that as the current through the diodes heats them up the voltage across them drops, then the current rises, the diodes gets warmer, and warmer, the voltage across drops till PHUT! its called thermal runaway As an aside if you connect each LED to an identical LED but the other way round you dont need to have a bridge rectifier to give a dc supply just ac.
NEVER run white, blue, green or uv "cmos" LED's on AC. Very little reverse voltage will blow them up short circuit....
sure, but then you have a nice flicker effect that'll drive you mad
recneps5 years ago
I have a preassembled 48-led light that I got for like $7 and it's great as a reading light, but 5mm led's just can't provide the same light like cfl's or incandescents can (as you've gone over in the efficiency earlier on) What I want to do some time is take a single, high power LED, like the SSC P7, pop that in a screw base with a driver and a heat sink. For less than 11W, you get an amazingly bright light and dont have to worry about the expected lifetime of all those small 5mm LED's. The hard part is finding a driver to supply 3.7+/- V at 3 amps to run the LED. I've seen drivers for ~2A, which will work, but 3A gives you the max brightness. The P7's are about $20 each and a driver $5, but you'd get a far superior light and the long life you'd expect of quality LED's.
VTY5 years ago
The end effect is nice in all three instances but the lumen maintenance of 5mm LEDs is quite bad. It means while it works OK for now you won't get the lifespan or maintain the light output over the potential life of the lamp. Certainly a nice Instructable and nice effects from the LEDS but not a workable solution to replace your GLS or CFL lamps with unfortunately.
dawp5 years ago
Hi: LEDs are not all that new. I have been using the solar powered yard lights for years. Solar panels and NiCad batteries have worn out (cheap things) the LED bulbs not. They are not very bright though.

Newer AC powered LED lights are quite new and the little 1.5W=40W (?) bulbs from Lights of America (available at Costco and some Walmarts) are very reasonable (3 for $15.00).

I replaced four 9W CFLs in outdoor fixtures (those date back into the 70s) with the LED lights. I used dead CFLs for their base and connected a miniature bulb socket to them. They provide nearly as much light directly underneath (about 8 feet high) as the CFLs at considerable savings.

The ballasts in the fixtures provide an extra kick (that was a surprise; i thought they would reduce the voltage) and the bulbs are getting 140Volts. I have two other LED bulbs in non-ballasted applications. I will be interested in seeing if the balasted LEDs have shorter life spans.

I also put one of the 4.5W = 75W (?) in an outdoor spotlight and that thing is real bright.

The great thing about these is the directionality. Very little light out the side and all concentrated beneath.

Another forum describing these bulbs in more detail explains you can dis-assemble them to get some bulbs for other projects.

Regards

partyfive5 years ago
cool, but it seems like the bulbs are a little uneven
oboist15 years ago
Great Instructable ! Maybe alternate some of the leds on both sides of the perf board. That would give the light a more even, "bulb-like" glow. I think the LEDs need to come down in price for real acceptance in the home. Come on guys, ramp up the production lines and drive down the cost for all of us ! I saw a small selection of LED bulbs at Costco. Amazing efficiency. I am going from memory but I think I saw a 40 watt equivalent decorative LED bulb that required only about 2 watts of power. There was a 75 watt flood light LED bulb that required about 8.5 watt of power. Thanks again for the eco-friendly Instructable !
bustedit5 years ago
i think i have that same belt - reversible tan n black perry ellis? mine's a POS and the lil crews always pull out of the buckle cuz im fat
Hey, I have the same belt and the same problem. :-)
Check into Tandy Leather and get rivet screws. It should lay flush and look nice on one side and screw into place on the reverse. If you use some lock-tight putty on the screw it shouldn't come out. Or get some shoe goo glue, should work as well.
Hardwyre5 years ago
I don't see any resistors on your LEDs. How did you get away without using them? I've built an AC LED using the resistor/capacitor trick and now I wish I'd found this (I think I did them before you published), as the rectifier seems to be a more clean and reliable method. But I'm still curious about resistors.
aandre (author)  Hardwyre5 years ago
Resistors are supposed to prevent the LEDs from flickering and they are recommended even with rectifiers. I, however, have had no problems with flicker, so I chose to ignore that hassle. =] If you want to use resistors, though, it would be a 1 ohm resistor per series.
gregr aandre5 years ago
I'm pretty sure resistors are used to limit the current that gets to the LEDs, and not to keep the LEDs from flickering.
You are right gregr. Resistor limit the flow of current. A smoothing capacitor could be used to reduce flicker, 470 - 2200uF would make a big difference. Be careful to specify one with voltage rating exceeding your supply!!
Hardwyre5 years ago
This is an excellent instructable; and thank you for answering my other question, just another one for ya. I noticed you made three sizes of lights; looking again at your calculations I THINK I'm understanding how you did it. For the small one you did one series of 46 LEDs, the mid was what, 2 series? And the large was 3? As long as you're using series of the number of LEDs you calculated, there shouldn't be much worry about blowing them, correct? I'm curious how the issue of maximum milliamps is handled.
I was trying to use the LED calculator at http://led.linear1.org/led.wiz to give me an idea, using 120volts as the input voltage, and trying different configurations, and it keeps telling me I need giant resistors at multiple wattages.
I'm just a little wary of spending lots of time to make a light and then have it over-driven and die after a handful of hours. I greatly appreciate the answers though.
Hardwyre,
I've taken a look at the Linear calculator and it seems to work okay (except that won't calculate for UK mains voltages - they're too high apparantly and so I'll just scale the figures anyway). Try:
Source voltage 150
diode forward voltage 2
diode forward current (mA) 30
number of LEDs in your array 72

You should get:
  • 220 ohm resistor dissipates 198 mW
  • the wizard thinks 1/2W resistors are needed for your application
  • together, all resistors dissipate 198 mW
  • together, the diodes dissipate 4320 mW
  • total power dissipated by the array is 4518 mW
  • the array draws current of 30 mA from the source.
Is this similar to your calculations?
The trick is to build a LED array that has a comparable forward voltage to the supply so the voltage differential is small so only small resistor is needed.
I hope this helps.
Matt
anyone doing it on 240volt?? i used to do assembly for a job, and we alway used a resistor in series, but without a drop down for voltage somewhere? has me worried.Kapow! they make one hellof a bang when they do go, same as diodes I found a 20light LED i bought commercially has done close to 2 years on 3 D cell batteries used 2 to 3 hrs for nightreading.
Al15 years ago
That's a good idea about using LEDs for the bridge rectifier. The only slight downside (I could see) is that those four LEDs would only illuminate for half of the AC cycle as compared to the main bank of LEDs so they may appear to flicker or appear dimmer.
charlieb0005 years ago
your rectifier can consist of leds too, in this case you have two arrays so you would need two led rectifiers
Jarl5 years ago
Not meaning to be negative, but... 5mm LED's are renowned for having a poor lifetime; about 6 months would probably be being generous. The reason no high quality commercial spots are available at a reasonable price is because they can't be made cheap yet still be good. In about a year, these 5mm LED's will be significantly dimmer than when you started. And also, colour rendition will be very poor with 5mm LED's. I'd advise sticking to incandescent in colder climates or CFL in warmer climates. It is possible to make a high quality LED array, but certainly not "cheap". Start with a rectifier, a quiet fan, a heatsink, several high quality LED's with a warm tint underdriven to about 100ma/die, a couple of capacitors to smooth output, and an avalanche diode to prevent the LED's being roasted by surges in supply voltage and you should get something good. It will cost a lot, though.
lasersage5 years ago
First off let me say, well done and it looks really good. Easy to follow and well thought out. I wonder what sort of climate you live in though? I live in the UK and bearing in mind the only significant waste energy from an incandescent bulb is heat, no energy is wasted. I would say for any home which regularly uses heating then incandescent is still the environmentally friendliest bulb going. Don't even get me started on CFLs and the mercury, but LEDs aren't super green you know. Think about the factories making them and the chemicals used. Its gotta be harsher than a bit of tungsten, glass and a vacuum. 100W incandescents are banned this year in the UK! Because our government wants to play to the press how green we all are. Load of rubbish. I want to be green, I put effort into it, but I think many people have been tricked into think incandescent is bad. If you use cooling/aircon any decent percentage of the year then perhaps incandescent isn't your friend.
BootCub5 years ago
What about the units over heating?? I have a friend who works for the robotics lab and one problem they have faced with the lighting units for the cameras using the LEDs is, they eventually over heat and burn up because of the power conversion. Any ideas or hints?
aandre (author)  BootCub5 years ago
Air conditioning! jkjk A heatsink on the opposite side would definitely help, but I don;t have any problems with heat. I mean they head up a bit, but to the extent of cold coffee. High flux LEDs, however, produce much more heat and will definitely need some sore of heat sink; this may be what your friend is using.
nolte9195 years ago
How much power in watts do you think each version of your bulb consumes?
aandre (author)  nolte9195 years ago
3.68 watts, 7.36 watts, and 14.72 watts, respectively. =]
DIY Dave5 years ago
I would use the base from an old CFL bulb for the screw in light part.
aandre (author)  DIY Dave5 years ago
I though of doing this many times, but it was always hindered by my irrational fear of mercury poisoning. I always imagined that I would break the CFL as I am prying it apart. I have already broken two of these bulbs by accident and I don't wish to take any more chances, being the clumsy person that I am. =]
Ceiling cat5 years ago
thetech101 mcd stands for milicandelas. Micro candelas would be represented by a Greek character known as a mu.(μ)
PKM5 years ago
Good work- seeing the cost is actually comparable with an expensive CFL, I think a couple of these could be a good time investment.

I was going to work out the power (to get an idea of how bright the bulbs are, I know how bright 5W of LEDs are etc.) but I don't see any current calculations in your numbercrunching. This makes me slightly twitchy, are you not at risk of overdriving your LEDs and not getting the bazillions hours of life you should? I may be confusing the theory of how LEDs work and how they work in the real world, however, so if this isn't really a concern then I'll ignore it and get on with life :)

Just for the sake of it, if we assume you are using the 13000mcd LEDs,

80mW per LED * 46 LEDs per string = 3.68W, equivalent to perhaps a 5W CFL or a 30-40W incandescent. However, living in the UK I'd be using more like 90 per string, which gives 90*0.08W = 7.2W, equivalent to maybe a 9W CFL or a 60W incandescent. Plenty to light up a small-medium room with white walls :)
thetech101 PKM5 years ago
Depends. The light output on LEDs is rated in mcd's (I believe it stands for micro-candela's). I've seen some 1 watt LED bulbs that had the same output (lumen-wise) as a 30 watt incandescent bulb. But they were on the order ot 40-50 US dollars! I'm sure some supplier has those LEDs that make those bulbs for pretty cheap. I think that if you built the bulb yourself, you could do it for only 20 US dollars and have the same light output as the more expensive 50 dollar bulbs. Great Instructable aandre. Rivals mine! One question, which LEDs from All Electronics did you use? Cause I know some that use less energy but rival some of their brother bulbs in brightness. Just search Category # LED-121. Not sure if that's what you used, but I did and they absolutely WILL blind you if you are not careful. Trust me! ;)
Thav PKM5 years ago
Besides the average power dissipated in these things and the lack of current limiting, there's also the matter of power factor. Diode bridges with no intermediate stage usually come with high peak currents. With diodes as a load, I'm not sure even a passive power factor correction filter would help that much. This doesn't mean much to the consumer, as power companies don't charge residential for low power factor loads like they do commercial/industrial, but increasing your power factor is a good thing for the power grid.
man those are fugly
But once you put a lamp shade over them, you just see the light.
Dipankar5 years ago
What happnes if one LED in the series goes bad? Will the other LED's glow? This is a problem with series connection. The lamp looks very beautiful otherwise.
Thank you so much for posting this! For the past week or two i've been bugging some of my more electronically smart friends for some information on what it would cost to build something like this. It's probably too late, but if you make another bulb, do you think you could take a picture of the soldered bottom? Also, do you anything about the energy savings that one of these provides? Great job!
aandre (author)  Weissensteinburg5 years ago
Here is a picture of the soldered bottom. What i realized was that it was taking too long to solder on row at a time and LEDs were a bit crooked. What did for the later ones was I bent both leads of each LED toward each other and clipped the leftovers. I then soldered quickly without getting the flux-induced headache and dizziness. As for the energy savings, each series uses about 3.6 watts, so it depends on the size of bulb you make.
IMG_0401.JPG
I'm don't quite understand the difference between your two methods of soldering.
aandre (author)  Weissensteinburg5 years ago
In one method, I only bend one pin toward the other and solder the joint. In the other method, I overlap them and solder the leads together, ignoring the soldering pads.
Ah, and the only difference is time? I'm extremley inexperienced with electronics, and i'm just betting on this being simple enough.
vern5495 years ago
Very good Idea. I would only add a appropriate varistor and fuse rated at slightly above the total calculated current of the LED's for safety. Overall very nice setup.
aandre (author)  vern5495 years ago
I did consider fusing it, and did ponder on how nicely it would fit inside the PVC pipe. However, all the contacts are nicely protected, so any problem would just trip the circuit protector. I will fuse the lights that I am going to put above my desk, though. I am simply going to wire them together without sockets, making me feel uneasy, so I'm just going to fuse it to be safe.
fegundez15 years ago
radical!!i am totally lame when it comes to electronics,i cant believe how simple this is.thank you for an excellent and really usable instructable!!
aandre (author)  fegundez15 years ago
That was exactly what I was going for; thank you so much!!
iPodGuy5 years ago
This is a great instructable. I'm no LED whiz, but the calculations and clear instructions makes me think I could also make these. Nice work!