14 Dec 2013

DIY Camera Trap

Have you ever wanted to capture a moment but couldn't because you weren't there at the right place, and right time? We all have.
Be it a tiger crawling out of its hiding, an intruder breaking into your house, a car running the red light or a runner crossing the finish line, one can seldom capture that right moment. This device precisely helps you capture the moment. With the help of a motion sensor and minimal circuitry, you will be able to build a camera trap that detects motion and captures its photo or video.  
The circuit is as simple as it gets, and why not?
"Simplicity is the ultimate sophistication"
Parts required:
  • Digital Camera
  • PIR Motion Sensor 
  • 3V battery pack
  • Optocoupler PC817
  • Power switch (optional)
  • LED indicator (optional)
All objects above absolute zero emit heat energy in the form of radiation. Though this radiation is not visible to human sight, it is visible to the PIR motion sensor. So the Passive Infrared Sensor uses infrared radiation to sense movement of people, animals and objects.
When movement is detected, the motion sensor's output pin goes HIGH. This signal is transmitted through the opto-isolator (or optocoupler) to trigger the shutter button of the camera and capture the moment.
A built-in variable resistor in the PIR sensor enables you to set the duration during which the output pin remains high after retriggering. In case you want to trigger video filming with this circuit, you will definitely be able to start the video but it will only stop filming the next time motion is detected.  

Go build this device right away or you'll miss on capturing the next brilliant moment!

10 Dec 2013

Solar CO2 Scrubber

We have extensively harmed our planet by following a careless and profligate lifestyle. But the Rubicon has not yet been crossed. If we act swiftly and boldly, we can still avert disaster. Among several other solutions, carbon dioxide scrubbing could help us move towards a greener and brighter future.

Carbon sequestration or carbon capture and storage are effective processes of extracting carbon dioxide gas from the atmosphere or from large point sources such as fossil fuel power plants, and storing it in underground reservoirs.

Although a brilliant concept, the present technology is still very expensive and not perfectly sound. So here's the concept of a solar powered carbon scrubber that could be the key in bringing down CO2 levels in the atmosphere.

This solar-powered appliance can be installed anywhere, preferably in locations with high CO2 levels such as traffic congested areas or industrial areas. This infamous gas which is harmful to the environment, has also its positive side.

The carbon dioxide that is extracted from the atmosphere through thermosiphon can then be recycled and used in chemical processes like making soda water or in fire extinguishers. It can also be pumped into a greenhouse and help in the growth of plants.

The best part is that this CO2 scrubber can be easily built by modifying a solar water heater.

The working principle of a solar water heater
Here's how the solar carbon dioxide scrubber works:
By exploiting the passive heat exchange based on the thermosiphon principle,  we let ambient air rise up the sloped glass case and bubble into a water container.
Next, by exploiting the varied solubility of gases, we separate carbon dioxide from the rest of the gases that constitute air. At 40C and at normal pressure conditions, about 600ml of carbon dioxide can dissolve in 1L of water while the solubility of nitrogen and oxygen is a mere 10ml and 20ml respectively. Refer here for details on solubility and here for calculations on the fluid dynamics.
So when air is bubbled into water, CO2 will dissolve in water while the rest of the air just bubbles out. 
The CO2 rich water then trickles back down the sloped glass tubes where it is heated by the sun and rises up again. In this heating process, the solubility of CO2 drops drastically and the gas bubbles out. At this point it can be tapped and used.

Further Improvement
Ingenious, right! Well, there's a snag...
Due to the poor concentration of carbon dioxide in the air, this process may not be as effective as it sounds. Probably this concept needs to be combined with other regular thermochemical processes such as reacting CO2 with calcium oxide or sodium hydroxide.
This energy independent concept of cleaning up the atmosphere through CO2 scrubbing needs considerable improvement but has a promising future.

11 Nov 2013

DIY Plastic to Oil

"Nothing to date has proven to be a truly effective or environmentally responsible solution to the burgeoning global landfill problem. In fact, many existing solutions have been just the opposite: costly, energy inefficient or equally as harmful to the environment as the plastic itself. "

It's only now, with the evolving pyrolysis technology, that there is a solution that is not only economically viable, but that is remarkably simple and "green" as well.

Pyrolysis is a thermochemical decomposition of organic material at elevated temperature without the participation of oxygen. In this process long polymer molecules are broken down into shorter chains of hydrocarbons with the help of heat and pressure. You can learn more about this process here.

This technology is growing in popularity and in demand. Commercial machines for home are still expensive. But with the following method, you can convert waste plastic to fuel all by yourself!
Here's how I did it:

Pyrolysis Setup
Lab experiment
  • You will be working with highly flammable substances
  • The fumes could be harmful, so avoid inhaling them
  • Make sure to keep the fumes produced in the reaction away from fire and from electrical points
  • Work in a well ventilated spaces
  • Keep a fire extinguisher and some water on stand by in can of an accident

Construction of prototype pyrolysis reactor
  • Procure a steel container with a tight lid
  • Build a condensation tube from copper/aluminum
  • Build a system for monitoring the temperature of the feed
  • Build a system to efficiently condense and collect the mixture of products

The pyrolysis process
  • Ideally, 1 kg of plastic can produce 1 kg of fuel. For getting a good yield, you can use polypropylene i.e. any plastic product with the mark:

  • Shred the waste plastic and put in the container
Reactor parts
  • Seal the container as perfectly as possible
  • Circulate water in the condenser
  • Fire it on!
Pyrolysis underway
  • Within minutes, the shimmering oil will start to drip from the condenser
  • If the condenser isn't sufficient, you can additionally bubble the gas into water
Black gold in the making

Flame test of the oil
  • If you want to obtain refined usable products from this mixture, you can do so by careful fractional distillation
Products extracted from crude oil 

Waste is a misplaced resource! Your trashcan's a treasure chest. So go make oil from plastic and: Stop depleting our fossil fuel reserves. Stop contributing to the landfills. Stop contributing to global warming.