We first get a 0.7 graphite from our mechanical pencil, place some wires on it, and rely a low voltage for a few seconds, 5V is enough for it to start to make smoke. Be careful not to burn anything, it is going to get hot!

Graphite glowing on 15V, around 10Amps

Depending on the graphite’s brand, you can see more or less smoke. It is not just the graphite burning, but the resin around it that cannot resist the temperature. Graphite itself can handle pretty well hi temperatures. But after some moments the smoke will decrease and the graphite will be consumed .

Graphite is one of the carbon forms that can be found in the nature and it is pretty conductive. In its more pure forms, it is used in industries to melt aluminium or silicon (1414 °C, 2577 °F).  But the tiny little ones you get from your mechanical pencil have several other things as clay and resin rather than just carbon. Those components make it to have a higher resistance than in natural form, but still less than 1.5 or 2 ohms.

Here is how you can make it…

According to ohm’s law: V = R.I, where V is the voltage and I the current, if we apply 12V on a 1.5 ohms graphite, we will have a 8 Amp current in our circuit. It means you have to be careful to buy a source that can handle at least that amount of current, otherwise you will can damage your source.

Because of Joule’s effect, it starts to get hot, and to make smoke. If you keep raising the voltage until 15V, it will start to glow – a very nice effect – but it works nothing different than a simple filament lamp. Just try not to look at it for a long time, It might be harmful to your eyes!

Smoke at 5V DC

If you hold it on for some seconds (be careful not to burn your terminals, the ones you used to hold the graphite, specially if they are made of rubber such as ours), the tiny little stick will consume itself and slowly brake apart in two pieces. It will turn the circuit off and you have to get another graphite for it to work again.

But a very important tip: DO NEVER CONNECT A VOLTAGE HIGHER THAN AROUND 15V ON THE GRAPHITE AT ONCE!

According to our tests, it sometimes explodes in several pieces and you could get hurt! But this experience can be quite safe if done carefully and correctly.

Take a look on what happens when you make 10A go through a simple 0.7 graphite! Quite cool effect, but be careful, is can hurt you if you make the experience wrong! =)

You might be asking yourself, why inside lamps the filament is not consumed as well? Thomas Edson had that problem, and found out that if you make a vaccum around the material it would last longer, and it really did!

Hope you enjoyed it! Thanks for reading

By Ricardo Boabaid