With an LCD display and no backlighting, a stock Nintendo Game Boy isn’t much good in dim lighting. A number of accessories were released over the years to shine some light on the screen for nighttime play. These got the job done well enough, but using them also meant that you had to burn through your AA battery supply even faster. Considering how fast the Game Boy already drained batteries, that was not a welcome feature.
Janus Cycle has just come up with an interesting — if not impractical — solution to both of these problems. He has built a system that powers a Game Boy with the energy produced by a candle. As a bonus, the candle light can also illuminate the display for late-night gaming. But be careful to never leave your Game Boy on when you nod off.
Installing a Peltier module (📷: Janus Cycle)
The build leverages the Seebeck effect, which converts a temperature difference directly into electrical energy. To harness this, Janus Cycle uses a Peltier module — normally used for cooling — as a generator. By heating one side and keeping the other cool, the module produces a usable voltage.
To make this work, a Peltier device is sandwiched between two heat sinks. A smaller black aluminum heat sink sits on the hot side, positioned just above a candle flame inside a makeshift cardboard combustion chamber. This enclosure helps trap and concentrate heat, maximizing the temperature applied to the module. On the opposite side, a much larger silver heat sink dissipates heat into the surrounding air, maintaining the temperature gradient needed for power generation.
To squeeze enough energy out of the heat, thermal interface materials proved to be important. Early attempts using thermal pads didn’t cut it, prompting a switch to thermal paste, which significantly improved conductivity and overall output. With careful tuning — including minimizing the gap between the flame and the hot-side heat sink — the system eventually reached the voltage required to power a Nintendo Game Boy via its DC input.
Even so, the setup isn’t exactly stable. While it can produce over 4 volts at idle, the voltage drops noticeably when the Game Boy is switched on, especially during the initial power surge. Sustaining gameplay required pushing the system to around 4.5 volts under load. That’s no small feat for a candle-powered generator.
Another persistent issue is thermal saturation. As the cold-side heat sink gradually warms up, the temperature difference shrinks, reducing output voltage until the console eventually shuts off. Without active cooling, continuous operation remains limited. It doesn’t look like we’ll be seeing any candle-powered Game Boy accessories any time soon.
