SolarPendulum

news

This project was posted on solarbotics!

intro

the solar pendulum is a project in Bug Bots, Junk Bots & Bots on Wheels. This sports an amazing self timing circuit so the pendulum 'resonates' automatically. don't mind the heavily populated circuit board at the top of the solar gate. it's mainly for show and structural support.

mechanics

it's difficult to make out in these photos, but the pendulum arm is supported by a piece of thread and a magnetic air bearing. this was my attempt to minimize the friction in the bearing. eventually i will replace the thread with a piece of steel (probably high e guitar string) for robustness.

for a closer look at the 'air bearing' check out these videos of the pendulum in simulated action (the sun was too bright and washed out all the details so i moved to a darker spot.

• Solar Pendulum video 0^? - Sorry for the dead link. I am trying
• Solar Pendulum video 1^? - To find where these videos are now.

FIXME: update URL!

these videos were shot with a CVS Camera so the quality is pretty low. It's been cranked up to a whopping 640x480@30fps so it's pretty descent for $20.

notes

• all of the magnets in the system came from hard drives so they are very strong. this helps hold up the pendulum arm as well as get help it swing higher.
• it works best in direct sunlight - even under heavy clouds the pendulum works very well as long as there is a line of sight to the sun.

why this is such a great project

any young BEAMers out there should definately give this project a whirl.

• Back EMF powers the led
• slight vibrations allow the system to self start
• solar powered means years of joy with no support needed (this is my favorite part of beam art - it's allows there for you)
• self timing
  • the magnet induces a slight current into the coil
  • this extra current coupled with the energy stored in the capacitors trips the power dump
  • the power dumped into the coil causes the magnet and coil to be attracted to each other
  • there is only 1 degree of freedom in the system so it starts to swing predictably
  • the orientation of the magnetic field pulls the pendulum towards dead center on the way in
  • this same field pushes the pendulum away from the coil once it passes dead center

SolarPendulumAddon

the SolarPendulumAddon is a page with a few ideas for addons to this project.

where to go from here

• tears of fire
• See more of my legacy BEAM projects
• See the AvronicsMicroMouse
• See my other ElectronicsProjects
• tell me about your projects - cougarvt at gmail
• go to your lab/basement/backyard or wherever else you keep your robot junk - start building!

Thanks for visiting! And a special thanks to solarbotics for posting this project.

-- ChristopherPepe - 17 Mar 2006