This lamp uses a Peltier thermoelectric module to convert heat from a candle flame into electricity. A Peltier module is a sort of semiconductor heat pump which uses electricity to transports heat from one side to the other, or generates electricity from heat transport through the module. If you heat a Peltier module on one side (for example, with a candle) and cool it on the other side (for example, with a fan), it will generate electricity.
This design use two TEC1-12706 Peltier modules connected in series. They are clamped between two heat sinks. This assembly is mounted above a tea light candle holder and can be adjusted in height. The bottom heat sink distributes the heat from the candle evenly over the surface of the Peltier modules. The top heat sink (together with a fan) keeps the cold side of the Peltier modules as cool as possible. Finally, a DC/DC boost converter raises the output voltage from the Peltier modules to a suitable level for operating a USB LED lamp.
A special feature of this design is that the fan is also powered by the electricity generated by the Peltier modules. Despite this, the power available to the USB lamp equals or even exceeds the value obtained without the fan.
The circuit is built around an LTC3105 IC, which is a 400 mA step-up DC/DC converter. This device can operate with an input voltage as low as 250 mV and is also used in many energy harvesting applications.
The kit includes all parts necessary to build the project: a fully assembled DC/DC converter board, acrylic parts with all fittings and hardware, Peltier modules, fan, USB lamp, and even a couple of tea lights. All you need is a screwdriver and some matches or a lighter.
Make & Elektor
The idea for this project originated from our friends at the German Make Magazine. It was selected by the editors of Make & Elektor to be one of the first projects to be refined and built into a kit by Elektor Labs. The result was published in Elektor Magazine edition 5/2017 (September & October 2017).