Homemade Lightbulb




Ever looked at a lightbulb and thought that doesn't look too complicated, I bet I could make one? With this Instructable you can!

This lightbulb is made entirely out of simple, mostly household materials requiring very little in special equipment. The basic construction includes a glass jar filled with CO2 and a graphite filament(Pencil Lead). This makes it a carbon filament bulb analogous to those made by Edison before tungsten became the norm.

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Step 1: Supplies

Materials Needed:

  • Jar and Lid
  • Pencil Lead
  • Maleable Wire
  • Heat-Shrink Tubing
  • 4 Machine Screws(I used 10-32 1/2")
  • 4 Nuts
  • 2 Acorn Nuts
  • JB Weld
  • Silicone
  • CO2 Canister
  • Short Length of Piano Wire

Tools Needed:

  • Drill and Bits
  • Wire Cutters
  • Needle-Nose Pliers
  • Vise-Grips
  • Scissors
  • Penknife
  • Screw Driver
  • Candle/Matches/Lighter
  • Air Nozzle(Only Unusual Tool Needed)
  • Oven
  • Voltage Source
  • Wire Leads
  • Multimeter(Optional)

Step 2: Hollow-Out the Screws

Drill a 3/32" hole through the center of each screw.

Two of these will become vents for filling the jar with CO2 and two will be for holding the wire hangers.

This is much easier if you first drill a hole in a piece of scrap wood to hold the screw in place. You may want to purchase extra screws because keeping the drill straight and centered is difficult and you will mess up at least once.

Step 3: Prepare the Lid

Drill 4 holes in the lid arranged with equal spacing as in the photo.

Use a penknife to score the area around each hole on both sides of the lid. This will allow the epoxy to adhere better.

Step 4: The Hangers

Cut two lengths of wire approximately 10" long.

Clamp the wire in the vise grips with about 1.5" sticking out on one side.

Hold the length of piano wire against the vise grips such that it is perpendicular to the wire.

Use the needle-nose pliers to twist the wire around the piano wire.

Repeat for the second hanger.

Note: For my malleable wire I used 19 gauge stainless steel, though any solid core wire of similar gauge should work.

Step 5: The Hangers Cont.

Release the vise-grips and remove the piano wire, there should now be a nice coil to hold the filament.

Take a piece of pencil lead and place it in the coil. It will be quite loose.

Using the needle-nose pliers, gently adjust the coil so that it tightly holds the pencil lead. Only make small adjustments at a time.

Cut any extra length off the end of the coil.

Repeat for the second wire.

Bend the two wires such that they will hold the pencil lead vertically in the center and so the long leads align with the holes in the lid.

Step 6: Insulate the Hangers

Cut a 1" length of heat-shrink tubing.

Place it on the wire hanger at the area where it will go through the lid, about 4.5" from the bottom of the longer lead.

Apply heat to shrink and adhere the tubing to the hanger. A candle is the easiest way to apply heat though a lighter or even matches will work as well.

Repeat for the second hanger.

Step 7: Attaching Screws

Mix a small amount of JB Weld and apply to the outside of the heat-shrink tubing.

With the head facing down, carefully place the screw over the tubing and JB Weld. The epoxy needs to fill the hole in the screw as this needs to be an airtight seal. Also be sure that the screw is straight on the wire hanger.

Repeat for the second hanger.

Step 8: Mounting on the Lid

Mix a small amount of JB Weld and apply to the underside of the screw head.

Push the screw through the hole in the lid with the head facing down(inside the jar).

Tighten the nut on the opposite side of the lid.

Again be sure the epoxy fills any gap as this needs to be airtight.

Repeat for both vent-screws and hanger-screws.

Let the epoxy fully harden for at least a few hours.

Check for a good seal by tightening the lid on the jar and blowing into one of the vents while holding your finger over the other.

Step 9: Final Adjustments

After the JB Weld has hardened place a piece of pencil lead in the hangers to test fit and make any final adjustments to the hangers' positions.

Remove the pencil lead and thoroughly wash(with detergent) and dry the hangers, underside of the lid, and inside of the jar. The interior of the bulb needs to be free of any contaminants that will burn and cause discoloration.

If you have some latex gloves you should use them for the final assembly, otherwise thoroughly wash your hands as well.

Place a new, fresh piece of lead in the hangers being careful not to handle it too much.

Tightly screw the lid onto the jar.

Note: I used 0.7mm lead, though 0.5mm, and even 0.3mm should work as well. In fact the thinner lead will have a higher resistance and should make a brighter bulb.

Step 10: Prepare to Charge

Place your assembled jar in the oven at 180 degrees. It will only need a few minutes to heat up.

While your jar is heating, apply a small amount of silicone to the inside of each acorn nut.

Step 11: Gas Charging

This step should be completed quickly so it may be worthwhile to practice.

Remove the jar from the oven and place on the table.

Use your air nozzle to blow CO2 into the jar via one of the vents. Do this for close to a minute. The cold CO2 should fill the jar while the hot oxygen-containing air will be forced out of the second vent.

While continuing to blow CO2 into the jar, screw an acorn nut onto the open vent.

Remove the air nozzle from the vent and quickly screw an acorn nut onto it.

Tighten both acorn nuts to ensure a good seal.

Note: This is the only step that requires an unusual tool, the air nozzle. I got mine a few years ago at Office Depot. It is meant to be an air duster, however regular canister air dusters will not work. They are often filled with flammable gases such as propane and if you use one you will be creating a bomb, not a light bulb.

EDIT: As suggested by many in the comments, dry ice could be used as an alternative to a CO2 canister. Without heating first, place a small piece of dry ice in the jar and let it sublime into CO2 which will displace the air. After the dry ice has completely sublimed close and seal the vents. Do not seal the jar with dry ice still inside because it will continue to sublime and creative positive pressure which may become a safety hazard. I have not tried this yet, but plan to soon.

Step 12: First Test

Connect your bulb to a voltage source.

When the bulb is first turned on it will smoke a little as it burns the small amount of oxygen left in the jar. Run it for about 30 seconds and then let it cool and the smoke settle.

12 - 24V should be perfect so long as it can provide a high amount of current. I used two 6V NiMH batteries connecting in series.

Optionally, use a multimeter to measure the resistance of the bulb and with V=IR find out how much current your bulb will pull.

However, as graphite heats up its resistance decreases so the resistance you measure before turning on the bulb will be higher than it will be when on. This is one of the reasons we now use tungsten filaments because tungsten's resistance increases with temperature.

Step 13: Completion

The bulb is now completed!

If you are running it from batteries be vigilant that you do not overheat your batteries.

Unfortunately it is not very bright so don't count on replacing your household lighting with it. You can try increasing the voltage to increase brightness, though be careful as the higher voltage you use the higher the current will be.

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89 Discussions


Question 3 months ago

Hi, i just made something similar. My question is that i want to do away with the batteries and run a 220V ac to 16 V ac 2.5 A power supply for it. Can someone please explain the circuit as the .5 pencil refills light up for a short while and then i think the transformer bombs out .


1 year ago

Nice layout, but the only problem with using CO2 is that it will break down at higher temperatures and release oxygen and eventually kill the carbon filament. Part of the smoke you're seeing inside the jar when you first power this on is actually wax melting/burning off.

You would get much better performance out of the bulb if you back filled it argon (from a welding tank from a MIG welder, or even a halogen gas (chlorine for example) like are used in regular halogen bulbs.

Alternatively, you might want to try an initial burn in of the pencil led in open air to burn off the wax, then put it in the jar and back fill it with whatever gas you want to use.

As also mentioned, putting a metal 'getter' may be something to try, but magnesium isn't anywhere near reactive enough to do the job. Barium is normally what was vacuum deposited on the glass walls of tubes.

Still, neat project though and i liked how you make the bulkhead electrical connections. Very nice!


Question 1 year ago on Introduction

Great project that I want to try, the only thing that I need to clarify is the type of "piano wire thickness". Not sure which one to get and when I checked Amazon there are different ones.

Would you mind to verify that?

Thanks in advance.


3 years ago

I like it. The dry ice method seems the most practical for filling the jar with CO2. It is easily available and you don't need any other devices. I would probably use a small bubble cup valve since no real pressure is involved. This valve is very similar or exactly like a beer or wine making bubble air lock valve.

See here: https://www.instructables.com/id/How-to-make-your-o...

Just let the dry ice sublimate completely ...and then seal the hole where the "J' tube comes out of the jar lid. Another great source of pure CO2 is club soda. Hooking up a bottle of the carbonated water to the jar with vinyl tubing would be easy enough. Just let the gas in and flow out through alternate hole that is similarly sealed as a one way valve. CO2 is heavier than air and will not be easily displaced once the jar is filled even if all you have is a small hole in the top of the jar lid. once the CO2 is flushed in, just seal the hole with JB weld or even solder.

I enjoyed your easy to follow explanation and detailed list of supplies and tools. Great job.


3 years ago

Using a brake bleeder vacuum pump to extract all the air out will help a lot with the smoke.


3 years ago

Using a brake bleeder vacuum pump to extract all the air out will help a lot with the smoke.


3 years ago

Using a brake bleeder vacuum pump to extract all the air out will help a lot with the smoke.


3 years ago

i ever read a book.in that book there is steps to make a lightbulb.it using candle inside the jar to remove the oxygen (remember how fire made)


5 years ago on Step 13

Returning to the roots! Scantelcorps if you want to make a diode or a triode the vacuum in the container must be as high as possible! The tubes made in factories use mercury vacuum pumps to get a super vacuum Oil pumps were also used. To get rid of the last atoms , a getter with magnesium is built during assembly in the container or bulb which get heated and this absorb the last atoms. If you would look at a glass tube then you would see a silvery patch on the inside. If the bulb get cracked then this silver turn milky white showing that the vacuum inside got destroyed.During WW2 Germans made tubes inside liquor bottles! They were not so effective as the vacuum obtained was too small but they worked!

2 replies

Reply 4 years ago on Step 13

I would like to ask a chemist about this because it occurred to me some time ago that CO2 is absorbed by lime and Portland cement. I wonder if a small chunk of CO2 absorbing chemical could be anchored to the inside, the bottle heated to reduce pressure then sealed. Finally the lime would hopefully absorb the last of the CO2 over time creating the desired vacuum. I've lost the paper but I think sulfuric acid absorbs certain gases. Hence my need for a chemist. The "getter" with magnesium in your comment really interests me. Any search terms that you can suggest would be very helpful. Since most of the gases they used were inert with no chemical activity I am glad to hear there may be an absorber that will bump up the vacuum of my less than perfect vacuum pump alternatives.


Reply 5 years ago on Step 13

Thanks for that Krokkenoster. Agreed that a vacuum is required in a radio tube as opposed to CO2. Gasses tend to absorb electrons rather than allow current flows across to the plate.

My suggestion was a bit tongue-in-cheek because I have serious doubts about the ability of the carbon filament to even develop a sizable space charge to begin with. Interesting to speculate and experiment with though.


4 years ago on Introduction

a thought for an easier way to get CO2 in and oxygen out would be to get a tub of water, after sealing the jar, take the two screws off that you used to feed the CO2 in and the oxygen out, but instead of heating it, stick the vents in water, the jar is upside down, so no water can get in, then, in one screw hole, pump CO2 in, and the oxygen will be replaced by the CO2 and it'll come out of the other hole, in theory anyway, I think this'd work better with a lighter than air inert gas, like Helium. If I'm not mistaken helium, being a noble gas is not flammable, and should do the trick, but I could be wrong.


5 years ago on Introduction

So, I see a lot of repeated comments, but couldn't find an answer to this question (which was asked before). What if I want to plug it into my wall outlet?

Assuming: a good gasket, using a bucket filled with inert gas so all the parts are in an inert bath as mentioned above, and potentially encasing the entire outside of the top in a slab of epoxy to help prevent leakage,

would it be doable to plug it into the wall?


5 years ago on Introduction

Do you still have to shake the jar well?

Nice replication of a household piece!


5 years ago

Magnificent, I'll certainly be having a go at this one. I love making things with a historic inspiration.


5 years ago on Introduction

Some may consider it cheating but if you want to use tungsten to make your bulb just take the filament out of a store bought light bulb. If you want to try it old school Edison burned strips of bamboo to make his carbon filaments. I think a plumber's torch and some bamboo skewers split into strips would work fine. You would have to experiment to try bamboo.


5 years ago on Introduction

Although i dont see much practical use, i think it is fantastic!!!

And I may make one, just because it is possible.!!

Would look great in some steampunk contraption


5 years ago

You could try using something called kanthal wire as the filiment. its a resistive alloy wire used in heating elements and Ecigs/vaporizers. I know I've built coils that have burnt white-hot in open air.

1 reply