Friction Flashlight

Goal of my project

To construct a flashlight that converts heat generated from body friction into enough thermoelectric energy in order to power a LED in a flashlight. The other objectives of this project are to test if:

1. The temperature difference between the palm of the hand and mediums such as air and water can be harnessed to produce enough electricity to power a LED bulb

2. Which of the natural resource air or water would be a better cooling system for the flashlight and make it more usable in terms of light intensity, duration of light, and portability?

Which property of Peltier tiles is used in this experiment and why?

The Seebeck effect is utilized since my project is based on having a temperature difference to produce enough electrical potential to light an LED. The Seebeck effect is a process in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances as temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side.

How will the Peltier tiles light an LED?

Since Peltier tiles can not generate enough voltage and current to light an LED by themselves, the current must be amplified through an oscillator circuit and a transformer.

Components and Construction of the flashlight using water

1. First an Aluminum rectangular tube is designed and welded on all sides with a larger opening at the bottom to fill with water.

2. A threaded Aluminum nut was used to seal the bottom, so that water does not leak as show in picture 1

3. Peltier tiles were attached on 2 side of the tube for greater contact with hand or arm-pit surface area as shown in picture 4

4. Each of the 2 sides of Peltier tiles are connected to an amplification circuit known as LTC3108 as shown in picture 2

5. An alternate to the amplification circuit can also be used as shown in picture 3 using n-channel MOSFET, common mode choke, resistor and protoboard. This is cheaper than the LTC3108.

6. The amplification circuit is then connected to the LED bulbs as shown in picture 2

7. After rubbing your hands to create heat due to friction, the flashlight can be held in the palm of the hand wrapping the Peltier tiles

Conclusion

After testing my second prototype numerous times, I consider my invention an overall success because it had met all of the following testing criteria:

1. The Flashlight produced 50 lux of intensity with just 2 LED bulbs

2. The Flashlight was easy to carry and weighed 350 grams

3. The Flashlight took less than 2 seconds to turn on

4. The Flashlight stays on for as long as it is held within the palm of your hands

5. When the Flashlight is held for 30 seconds - the light stays on for another 30 seconds

6. The flashlight took less than $50 to construct

7. The flashlight was sealed tightly without any room for leaks

However, my first prototype works better with air since it is small, compact and more portable. But since it is not leak proof (with water) and had only one LED bulb attached, it is good for using as a flashlight where dim lighting will serve the purpose.

Recognition

Presentation materials and references