Some months ago, while browsing Instructables I came across a post by Joohansson (https://www.instructables.com/member/Joohansson/) showing how he had used the thermo-electric Peltier effect to power a fan with a small candle. Subsequently he has also shown how to use a similar device to make a phone charger. A similar project was posted more recently (https://www.instructables.com/id/DIY-Stove-Fan-for-under-50/) and both of these posts give some of the theoretical background as well as useful links for such Peltier devices.In essence, Peltier devices are thermo-electric couples which, when powered, produce cooling, for use in things like wine fridges, or when used in reverse across a heat differential, can generate electricity. By placing a simple, store-bought Peltier element between a heated heatsink and a second, heat-dissipating sink, enough electricity can be generated to run a small motor, which can then turn a fan.
I was particularly attracted by the aesthetics of Joohansson's creation and decided to make my own from scratch, using only the central Peltier element and a motor which I bought on e-bay, plus a single aluminium heatsink, as my starting point. Every other component was made from re-purposed bits and pieces from the scrapyard or my boxes of gleaned finds and left-overs. I also wanted to make the device functional, so I decided to use the fan to help distribute air-freshener.
I have not given a step-by-step guide so much as a "show and tell" because the details of what one makes in these sorts of projects is so dependent on what you have available.
Step 1: Materials and Methods
For this project I bought the following 2 components
1. Mabuchi RF-500TB "Solar Motor" (0.5 -1.5V, 380-1280 rpm). Approximately U.S.$10.00 on e-Bay
2. An off-the-shelf thermo-electric (Peltier) module (68W). Approximately u.S.$20.00 from Jaycar electronics.
An aluminium heatsink was harvested from an old computer and all the other components were made up from recycled copper piping, brass stock, brass wire and some leftover rosewood.
The heatsink which forms the cooling side of the device was made from a solid brass gas distributor, to which were fixed 3 segments of a copper heating-exchange element from a truck radiator. As long as there is good contact between the heating element, the lower heatsink, the Peltier unit and the cooling heatsink, the device will transfer heat and will generate electricity and hence, work. The rest is aesthetics and doing whatever takes your fancy. Note that to make the heat transference better, the opposing faces of the heating and cooling sinks should be well polished and the contact between the Peltier unit and the heatsinks augmented by a good layer of thermal conducting paste, available online or from electronics component suppliers.