Picture of LED Lightbulb
This was just a lark that had been itching in the back of my head for a while. It's a mains powered LED lightbulb.

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Step 1: Supplies

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There's not too many things you need for this project.
An incandescent light bulb.
A .47 microfarad 200V capacitor.
1/4 watt 1kilo ohm resistor
a pair of leds
and miscellaneous things.

Step 2: Assembly

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You need to start by cleaning out the lightbulb, there are numerous instructables with this step and I will forgo it here.

The circuit consists of two LED's wired in opposition, I ground down the LED's just short of the die and glued them together to make a single double LED. Twist the legs of the LED's together, on one side solder the capacitor, the other the resistor. Simple.

Step 3: Test

Picture of test
Here I'm holding the circuit with a clothespin and sticking it into an outlet, this is of course, the recommended test procedure. ;-)

Step 4: The Bulb

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Stick the circuit into the bulb and use some hot glue to hold it in place, be sure to have some cold water, you will burn you fingers. Try to center the LED in the bulb. Once you have the circuit in place, bend one of the leads over the base and secure it with aluminum tape. The second lead is twisted around a brass screw inserted into the hot glue. Check for shorts and you should be good to go.

ajones401 year ago
If I live in the US, should the capacitor be 110v? Standard wall outlets are 110v here.
andr3w992 years ago
I have a question... since i am young, i order from a VERY cheap website... they are the same quality items & i would like for you to help me...
i order from this website is EXTREMELY cheap, but sometimes it is hard to find what you are looking for. Can u help me find the 47 microfarad 200V Capacitor & the 1/4 watt 1kilo ohm Resistor... i dont want to order something, have it turn out its not the right type[s] and have it burn or shock me... thanks
boyrock3752 years ago
by the way be careful cleaning out the bulb.....when breaking the glass base inside there is an inert gas in there so be sure your carefully and i suggest doing the initial breakage outside
.Unknown.2 years ago
How much current do you think this thing draws, roughly?
qwerty1562 years ago

I pulled out a capcitor from one of those cheap chinese flashlights that charge from ac
It looks a bit like this

Do you think i should give it a try?

I live ina 230v area
Whoa! If you're not sure you shouldn't mess with high voltage! That stuff WILL hurt you. Go through the calculations and read up on the capacitor and safety. Then try it but NEVER mess with mains voltage if you feel uncertain about anything.
i saw your post just after i tried it lol!

Anyway, the resistor burn out but the leds are fine.

Protip - DO NOT TOUCH THE CAP! Nasty suprise!
electric shock?
Probably it was damn hot and he burned his fingers.
qwerty156 Sowee2 years ago
nope, it was a shock. scared the crap out of me!
wd00133 years ago
To:Tool Using Animal

Awesome post. I especially like the usage of a filter cap in lieu of a (very unnecessary) bridged rectifier. I like bridged rectifiers in larger arrays, but simplicity is always more elegant. Keep 'em coming!

To: Everyone else

As an engineer that does waaaaaaay more dangerous experiments than this, let me tell you all that:

A: There's not enough current draw from that small apparatus to do anything really harmful to the cloths pin. During a malfunction, the cloths pin could get charred, but there would be absolutely NO fire.

B. At the end that is being held (the side with the LED - this side of the resistor and cap), there is only a miniscule amount of power. It takes high voltage to create any kind of arcing across the cloths pin (much less to the fingers pictured here). I'm talking 500+ volts. Voltage levels of 120 - 240 (depending on which country you're from) simply will not arc in such a fashion. Honestly, though you would feel it, there is (most likely) so little power (on the LED side) that you could comfortably touch the leads for a couple of seconds, as long as it was only one hand touching. Of course body chemistry, grounding, humidity, your own level of intelligence , and many other factors means that mileage will vary here. DON'T BE STUPID - MY RESPONSE IS SHOWING THEORY NOT PRACTICE!

The reality is that "real world" electronics testing in the A/C world is typically (at least) this dangerous. Common sense, knowledge, and study are your best friends in the lab (at home or work), so read a book folks!


dany_mid4 years ago
hi I live in Europe and here my socket electricity has 220V at 92 mA 50 hz please could you tell me what capacitor should i use?
Your socket does not put exactly 92 mA. You have to measure it with a load. I think you can use 2 of these capacitors.
Adam Manick3 years ago
A variable capacitor can give you adjustable voltage
jules153 years ago
How did you come up with the .47uf cap.. i want to know how to make other voltages like 6,9,12.. Is there a formula?
manuhui4 years ago
Hi, if i want to put more than 2 LED, lets say 8 or 10, I put them in pairs, each pair opposite and with their resistor, in parallel or in series ? is that viable ?
megapix manuhui3 years ago
You would put the pairs in series, and you would still only need one resistor and capacitor for the string. There are a couple of instructibles which do exactly that.
I have the same question, I have an idea for a simple 9 LED array that should make it so that it will work almost as well as a traditional bulb. I just don't exactly know the circuitry for it, and this ible was a good place to start. I still need to know if I should put them in series or parallel though.
noingwhat3 years ago
Is it really necessary to wire two LEDs in opposition? Is the flicker noticable if you didn't?
Yes, its necessary, but not because of flicker. LED's have a "reverse breakdown voltage" of only about 5 volts, so a single LED would break down as soon as the line voltage reversed direction. Although the capacitor and resistor might prevent instantaneous destruction, the LED lifetime would likely be reduced. By putting a second LED across the first LED, with opposite polarity, the two LED's protect each other from high reverse voltage, and double the light output, and reduce flicker. What a deal!
Tool Using Animal (author)  noingwhat3 years ago
Dunno, try it and let us know.
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Ah yes, I forgot about that. Thanks!
KG4ZUZ3 years ago
You DO NOT have to use a .47 uF mylar capacitor nor do you have to use a 1k ohm resistor, I have built 5 of these lights using a capacitor value ranging from .1uF to .68 uF all at 250 volts or more, I also have used a .uF capacitor with a 2.2k resistor and they all work great. You can use almost any value cap and resistor combination as long as the caps are at least 250 volts.You MUST use a MYLAR type of cap though
noingwhat3 years ago
The wooden clothespin wouldn't conduct any electricity, but there is still the chance of, as he said, fire, or also a spark either from the LED to you, or from the LED to the clothespin spring to you.
cicusninja3 years ago
Is this circuit for 250VAC or 125VAC ? what do I have to use for 250VAC?
w0rm53 years ago
Despite of what my freind below says, I built it with a 0.47 capacitor, 1KOhm resistor, conected, lit it up ok, oh really good.......... NOT, after about 1 hour the resistor burned out, so in 127V, it overheats.
w0rm53 years ago
Hi, nice one, but what about the capacitor plarity, how do I hook it, negative side to led or the oether way? Thanks
Tool Using Animal (author)  w0rm53 years ago
You need a non polarized capacitor.
spyler034 years ago
where can i buy the .47 microfarad 200V capacitor?
search for orange drop capacitor

These are typically 600V, which is over spec, but OK (under spec would not be OK).

You could also take apart old power supplies, if you know what to look for and can do it safely.
Radioshack carries both capacitors and resistors. They also carry LEDs for around $2.49 for an ultra bright LED.
jules153 years ago
Thank you very much for posting this project. I just finished it and it works great.. Hope to save money : )
Darksun0103 years ago
Went to Radio Shack and they didn't have a .47 microfarad cap 200 volts, but they had a .047 microfarad cap 630 volts.  Will that work???  It cost a $1.59.
taikombuter4 years ago
I'm a new member ! So, i need you explain more to connect 2 led together.
You can post 1 picture of wiring diagram. Thanks !
alzrc_13j4 years ago
ei what if i use a polarized capacitor???would it make some difference???i cant buy a non polarized capacitor in our place hahahahaha....
Tool Using Animal (author)  alzrc_13j4 years ago
At best it wouldn't work, at worst, BOOM!

tjmortenson4 years ago
Are they regular 3 volt or 120 volt leds?

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