Generate electricity with a candle

What you see above is a generator that converts heat to electricity. [Reukpower's] thermoelectric lamp is one of those hacks that makes you scratch your head even though you understand why it should work. The heart of the system uses a Peltier cool, just like the thermoelectric solar generator. When there is a temperature differential from one side of the Peltier to the other a small current is generated.

In this case a candle heats one side and a heat sink cools the other. The tiny voltage picked up from the Peltier’s contacts is then boosted using a joule thief. We’ve seen LEDs powered with a joule thief before, benefiting from their own low power consumption. In this case, the boost circuit is scavenged from an emergency phone charger and probably achieves higher efficiency than if he had built it himself.


  1. octel says:

    Nice writeup

    “Peltier cool”

  2. Fry-kun says:

    So… a candle is used to power an LED?

  3. Agent420 says:

    Need to turn this into a perpetual energy device, by using a heating element to create the electricity ;-)

  4. DerAxeman says:

    Linear Technology just announced a new chip they will be making for turning this type of electricity into something useful. Its the LTC3108

  5. red says:


    It wouldn’t be perpetual then. One would need some source of energy to power the heating element. Unless, you were joking.

    NASA has used such but instead of using a candle, their used radioactive material on one side for the heat it would generate and then the other side is cooled by the temperature around it.

  6. red says:

    Skip over the tense changes, ^ and it should make sense. |

  7. christopher says:

    It’s called a Stirling engine, and it’s not perpetual.

  8. M4CGYV3R says:

    This isn’t even a stirling engine. It’s a peltier cooler used backward instead of electicity->cold it goes heat->electricity.

    • nybbler905 says:

      The Sterling engine is used backwards for in house AC units ( look at the big ugly box outside some homes and the data sheets of the year round ‘ heat harvesters ‘ ). The difference on the Sterling side is that a motor spins the Sterling to control which way the heat is ‘ pumped ‘ ( to the house or from it in summer ). That said and getting back to the candle power, it’s an electric version of it. Instead of an LED ( to prove it is doing something ) the power can go in to any kind of buck converter to recharge a cell phone or other consumer device instead of lighting up a LED. Still, it is a nice little setup in the photo, the issue with a Joule Thief I have had is the coils and internal ‘ resistance ‘ to the base and the chance the power is backwards. Personal pref is germanium diode rectifiers and capacitor ( diode bridge stolen from a really cheap shake light WITH the capacitor )

  9. SparkyGSX says:

    Would you please try to acquire some very basic knowledge about electronics before write such bullshit? A joule thief does not “boost a current”, it’s a boost converter that converts a high current at a low voltage to a higher voltage with a lower current. The voltage from a Peltier element used in this way is (apparently) to low to light up an LED, while the power supplied is sufficient.

  10. hum4n says:

    this is called a “Seebeck Generator”. The last issue of “Make:” had a good tutorial.

  11. Marty says:

    Seems like a really overly complicated way to generate light….

    Can’t you just use the candle?

  12. jan says:

    i went to the comments to post what sparky said: a joule thief is not a “whatever” booster just a converter…
    mike u r really not as bright as you would like it to be… pls read some wikipedia articles or google around before you try to explain us the world next time

  13. samurai says:


    Don’t be a smart ass. Lighting an LED is just the obvious example to show that power is being generated. Would it suffice for you if instead of an LED, this setup was powering an Arduino?

  14. pookey says:

    I have experimented with similar contraptions and circuitry to charge small batteries. They can then be used to power an mp3 player, a cell phone or a QRP transmitter.

    You have to be careful when heating a peltier junction with a candle or other open flame. It is comparatively easy to damage the junctions, or even cause them to come apart with excessive heat.

  15. CampGareth says:

    What I’d like to see is some more hacks involving Sterling engines, far more efficient as far as I know and so a lot more realistic for device charging. Only issue is that every supplier I can find after not searching for very long sells toy size versions as opposed to useful size versions. Where did the guy who powered a 12kW generator from Sterlings and sunlight get his (yes that was featured on hackaday)?

  16. Michiel says:

    OMG.., what a great project.
    I’m thinking of a array of candles and peltier elements, this way you can get a PIC and make a flickering led candle…. :D

    Oh…, and maybe that would make it “the most useless machine”.., haha :)

  17. durp says:

    CampGareth there’s a good chance that person either made it themself or got it custom made.

    Heavy duty stirlings are far from commonplace :P

    They’re entirely doable with machine shop access though.

  18. Goddard says:

    This is so cool. I would be interested in hearing more about this…please post more cool stuff like this.

  19. Josh says:

    Good post, this is what keeps me coming back

  20. Doug says:



    You cannot get past some bad terminology to appreciate a hack?

  21. A. Karttunen says:


    Thanks for posting a link to the datasheet of that LTC3108 “Ultralow Voltage Step-Up DC/DC Converter and Power Manager” !
    I have been waiting for many months to see Freescale finally starting to sell a similar chip they advertised already about a year ago:

    It seems this chip from LT should do about the same thing?

    Now I just hope some net-retailer like Solarbotics starts selling them also in small batches. (And if they are available only in SMT-packages, they could solder them to something like DIP-sockets?)

  22. Dave Salerno says:

    The LTC3108 is already available in small quantities from Digi-Key (

  23. Dave Salerno says:

    The LTC3108 is already available in small quantities from Digi-Key (

    Happy Harvesting!


  24. MadScott says:

    I dimly remember an article about a Soviet Union radio that ran on a thermocouple array (same principle) – used for areas that didn’t have electricity but could manage a bit of kerosene for the heater.

  25. Eric says:

    If you feed the amplified voltage into a fan that would cool the ambient side of the peltier unit more effectively, then you would really … um…

  26. Urza9814 says:

    I can remember when I was younger my mom had an old set of encyclopedias from when _she_ was young, and they had instructions for a candle powered radio. Wish we still had those. It was pretty simple to make too. And that was printed…back in the 60s at the latest.

  27. pookey says:

    I recall reading this article many years ago in Popular Science… and I found it online!

    Here is a radio powered by thermocouples (same idea) for use in remote villages in Pakistan. The heat comes from a candle. The article includes construction details.

  28. janin says:

    Well you get the light of the candle plus the light of the LED (which looks quite bright … hard to tell from the picture). So it adds a benefit, besides being a fun project.

    Very interesting chip by LT … Minimum start-up voltage = 20mV ? Impressive.

  29. Michiel says:

    Maybe you can use some sort of waterreservoir at the top, this way you can keep it cool and it wil look much better. :)

  30. dudegalea says:

    So it turns heat into light… hmm, it’s the starting point for low-res infrared goggles! ;-)

    Cool hack.

  31. Urza9814 says:


    I’m pretty sure that’s the _exact same diagram_ from the encyclopedias I mentioned! Haven’t seen that in years!

    Also – note that the instructions call for asbestos cement.

  32. Jeditalian says:

    There are so many possibilities when you are working with Peltier. i could build an emergency candle-powered phone charger.. if i hadnt last my peltier. it was small as shit anyway and a wire fell off. if onliy i had some Tellurium.. lol i want to buy some of that “environmentally friendly shotgun shot” cuz they use bismuth instead of lead. but for really good peltier you need bismuth Telluride, or what i plan on doing in the future, experimenting with other alloys/metal combinations. the possibilities seem endless, what you might come up with when you pass some form of energy across/through/around different combiniations of the elements. i mean, if copper and bismuth plus electricity moves heat, creating a distinct Hot and Cold, doesnt it seem possible that you could use some combination to make North and South magnetic fields, and if that was reversible like a peltier, then you could use magnets as batteries. magnet batteries would be more readily accepted into society than Nuclear power cells. Fission or Fusion? o yea fission not good choice for powering your auto lol. but i think if i did enough research into things similar to the Peltier effect, i would eventually have discovered the Fusion Cell, solving the energy crisis. but if i dont get a lab or some funding i would expect the world to have to wait until about 2025 before the life-changing breakthrough discovery that makes lightsabers possible

  33. Michiel says:

    LOL…, I’m still waiting for someone to give me a lab… :P

  34. Michiel says:
  35. A. Karttunen says:

    There’s a Swedish company, which makes among other
    things “Thermoelectric Mobile Charger” integrated
    with Trangia camping stove. See the first Product sheet at:

    Electric output is 9W when the water is cold,
    and 4W when it boils.
    Maybe intended for the Swedish army?

  36. stealth says:

    This would be great were i live.. in summer we get as hot as 128F but any other day in summer is around 110F to 117F… and i live in california.

  37. Rex says:

    This isn’t going to do you much good in 128F weather. Remember, it doesn’t work from heat, it works from the temperature difference. So without some cool you get nothing.

  38. Michiel says:

    These peltier elements could make a nice wall, 20’C inside and -5 outside in the winter here in the Netherlands. :)

  39. derp says:

    Michiel, that’s the kind of thinking I like to see :D

    though that situation wouldn’t be reusing waste heat, it’d be making electricity off the heat from your furnace…

    I have had a plan of making a fixture on a cabin’s chimney off a wood-burning stove. the hot chimney is venting outdoors where the hot smoke and air is lost, so put a peltier array on there to use that waste heat against the cold winter air to charge some batteries or run some fans to push heat from the stove inside around.
    The obvious problem here is smoke and creosote buildup on any heatsinking inside the chimney causing disasters in the long run.

  40. Jaythenovice says:

    I think it’d be a neat survivalist tool. Attach the hot side a peltier plate to a metal plate and build a campfire on it. As the coals fall to the bottom the heated plate transfers energy to the peltier and can charge batteries for flashlights or GPS systems while you sleep. In the morning everything is charged and the plate should be cool enough to pack up and keep hiking.

  41. teenagegeek says:

    That’s so cool.

    To solar panels use heat energy as well as, er…

    light energy I think?

  42. 5on3off says:

    that’s crazily cool! I’ll have to try it out…

  43. jeezem says:

    very cool

  44. GardenSERF says:

    I think heating my cup of tea with the candle rather than the electricity produced by this gizmo is more efficient.

  45. Roman D says:

    @MatScott: In Soviet Union they put you under the candle and use the acustic energy of your screams to power a hamster wheel…. poor guy needs his excersise.

    But seriously, this is great, just makes integration so much easier.

  46. jeditalian says:

    they pull alot of wattage when you’re using them to move heat.. but a thermoelectric phone charger would be great for a power outage when you burn candles anyway, and if its a winter power outage, you could load the top with snow and have it drain into wherever you want melted icewater.. your plants?. candle on the bottom, snow/ice on top. or if you lived in an igloo, you could have a giant peltier pad where your body heat powers small things like calculators.. maybe cheap personal radio.. lol where are the multibillionaires? Hackaday needs its own lab where all the hackers can come together and make cool shit. then we could think of making shit like a robot that builds scaled down versions of itself, which in turn build scaled down versions of themselves, until you have Nanites :D

  47. jeditalian says:

    but what i’ve always wanted to do is to line a cars exhaust system, or a section of it.. voltage regulate it and store the excess in a battery. then you are pulling your 12 volts, running inverters, etc. without bogging down your horsepower by putting extra load on the alternator. it would work best on days when you wouldnt need the AC because its friggin cold. passive heatsinks on the ‘cold’ side. its just not worth the time and money involved, tho.

  48. Gary Fischer says:

    you will get the light of the candle plus the LED light. That sounds sinply amazing!

  49. Hi,
    Your post generated a lot of heat.

    Cool idea!
    Nicole Rigets

  50. Kevin says:

    Intresting one! Its actually nice when we invent something like this and electricity from candle is a creative one. There is something like this I tried using lemons to generate electricity.
    Cool !! keep adding things like this.

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