Editor's Note: The following post shares an original idea and conceptual write-up sent by Mr. Ike Higgins. The original text and details provided in the communication are published below.
Introduction
For a little while lately I’ve been trying to come up with something more practical. I started looking for a new idea. I thought about “People Power”. What to do with people as the input power. This is not new. We already have technology where the clothes you wear while walking will actually charge your smartphone.
People power. I was sitting in my rocking chair trying to think of something that humans just normally do that I could harvest useable power from. Just sitting there rocking back and forth. And it hit me. Talk about irony.
People Power: The Rocking Chair Reading Lamp
Rocking back and forth causes the back end of the rockers to move up and down about 2 inches, depending on how hard you are rocking. 2 inches is at the short end of the possible range.
Relatively relaxed rocking takes about 1 second to complete one cycle (1 Hz). What would happen if the rockers were attached to a magnet? The magnet would move up and down. What can be done with a moving magnetic field? You guessed it. Electricity.
I worked on this for a while, and did some preliminary math, and found that I have another relatively simple electro-mechanical design, and valid chain of physics.
However, when attempting to do the math I found to my detriment that I am just not capable of doing the detailed design work I once was fairly good at. It made my head hurt.
Below are basically my notes of the conceptual design. Just preliminary calculations and ballpark component parameters.
I reached out to my friend Swag, who has proven he can do detailed circuit design to provide an actual circuit that works, to collaborate on this concept.
Here is the basic diagram of the Rocking Chair Reading Lamp.
Rocking Chair Reading Lamp Assembly
System components include Rockers, Cable interface to rockers, Bearings, Spring, Magnet, Electronic circuitry, and LED Lamp / Output power to LED.
When you rock backwards, the cable pulls the magnet up 2 inches and stretches the spring. When you rock forward, the spring pulls the magnet down 2 inches and the cycle is complete at 1 Hz.
Electronic Circuitry Specification
The electronic circuitry consists of a Coil around the magnet, Bridge rectifier, Smoothing Capacitor, LED Driver / resistor, and LED in Lamp.
The magnet that moves through the coil would be a Neodymium of approximately 20mm x 10mm thick, Grade N35-N52, depending on the coil’s distance from the magnet as it passes through the coils. The coil will take approximately 1,000 turns of 30-32 AWG to get to 5V. The Bridge rectifier takes four low-voltage Schottky diodes. At 1Hz the bridge should recharge the capacitor close to twice per second using a 10mA LED load and a 10,000 uF capacitor.
The Smoothing capacitor is around 4,700 to 10,000 uF, rated for 10V or higher. The larger the capacitor, the smoother (continuous illumination) the output.
I believe there should be a 6.8V or so Zener diode across the capacitor for protection if the generator can exceed the capacitor’s rating, and deal with the possibility of the generator’s possible excess power. The LED resistor could start with around 220 ohms. The LED is a normal 5mm white LED, or could also use an Indicator LED.
Using Magnet-and-Coil Linear Generator
Although the rocking chair concept by Mr. Ike offers a practical design, integrating a magnet-and-coil linear generator (shake charger) into the chair's frame presents a compelling alternative. This self-sustaining setup converts the user’s continuous rocking motion into electrical energy to illuminate the lamp
Using Eccentric Pendulum Mass
Another approach is to integrate a permanent magnet (PM) motor fitted with an eccentric pendulum mass. As the chair rocks, the swinging pendulum drives the motor shaft back and forth, converting the oscillating motion into electrical energy. The example figure can be seen below:
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