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Student looking to create an energy harvesting circuit

Former Member
I am a student who is researching methods of "harvesting energy" through the means of a few electrical effects.  These include the piezoelectric effect, current generated in certain materials in response to pressure, and the thermoelectric effect, current generated in certain materials in response to a temperature differential.  I am looking to create some type of circuit that uses these principles to power something (a light or a small fan).  Can anyone suggest how I could go about doing this? I am looking at this (http://us.element14.com/peltier-elements) page for possible Peltier Elements to base the circuit around.  I am guessing from my limited knowledge on the subject that I will need something to translate the changing energy output of the thermoelectric device to a more constant (DC?) supply.  What do you think would be something reasonable to run off the Peltier Element?  Do you have suggestions as to what else I need to create a well running circuit to demonstrate the Thermoelectric Effect?
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    Hi Josh, Peltier elements generate electricity due to the seebeck effect, so your going to firstly want to look at how you will heat/cool either side of the element, the more the difference in temperature the more power it will generate, however peltiers do not have great efficiency and a single cell will not power alot (prob a few mA). For the purpose of example a simple circuit could involve driving an LED directly, you could use an RC circuit to do this better. I don’t want to spoonfeed you all the answers so I would recommend you experiment with cells using different methods of heating/cooling sources and measure the results with DVM, and then work from there. There are plently of low-power circuits on the web that could work well with a peltier, such as a joule thief. If your looking to get a more constant current, then capacitors and low-drain regulators are worth looking into.
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    Josh,

     

    Where do you plan on using this Peltier energy harvester?

     

    Here is a circuit that is powered by a Peltier and senses temperature. Low power sensor applications would be a good use of the effect. The more of a difference in between two surfaces the better your project will work.

    image

    See more about this fully worked out project at Linear's site.

    Here is another.

     

    First of all, I recommend learning as much as you can about the Peltier. Build some projects that are already worked out, like the two above. Then, I would say, you know enough to venture out to build your unique project.

     

    I have a project idea for you to try in the future:

    Use the heat source from your furnace or water-heater to detect moisture on the basement floor. (If you live in a house.)

    Or a similar heat source for detecting window condensation. (For high-rise apartments, window moisture is an issue.)

     

    Cabe