16 May 2014

Solar Scare Mosquito

Every year, over a million people are killed by malaria. The only solution to this problem is to destroy mosquito breeding grounds and curb the problem at source. As mosquitoes breed in stagnant water, I concluded that surface aeration would be one of the best means of eliminating breeding grounds.

So I built a device that generates air bubbles at regular intervals and effectively produces ripples up to a radius of 2 meters (sufficient for most urban water bodies). The device automatically switches on when it comes in contact with water an alarm alerts if the water body dries up or someone tries to remove the device from water. At less than $10, the device is cost effective and being solar powered, it is energy independent and maintenance-free.

Here is my Youtube project presentation: Solar Scare Mosquito

Note: You will have to see this video to fully understand and appreciate the project. 

You can also check out the Step-by-Step Instructables of this project on: Step-by-Step Instructables.


More than half the world's population is vulnerable to vector-borne diseases. These diseases, namely malaria, largely affect children and poor people and there is no
promising solution to eradicate it.

Question: So how can we control malaria using technology?

As mosquitoes transmit malaria and water stagnation is the primary cause of mosquito-breeding, by preventing water stagnation, it should be possible to curb malaria.

Hypothesis: By devising a surface aeration system for small water bodies, it should be possible to control mosquito breeding.

Building the device

The device comprises of the following parts:

Bubble aeration
Of the various aeration methods, I chose bubble aeration to create surface turbulence and I used a portable aquarium pump as a bubble generator.

Solar Power
As the aerator needs to run perpetually, it is not practical to make it battery-powered. Thus I made it solar-powered.

The air-pump is also timer-based and runs at intervals of 10 minutes to increase its life.

Automatic Start
As in the case of floodwater, rainwater, roadwork and construction sites, no arrangements are made to treat such temporary water bodies that are potential breeding

Get your hands dirty

This is the best part of the project...building the circuit! It takes no time to build this circuit which could potentially save you from those nasty mosquito bites. So get tinkering!

Electronic Parts:
  1. 6V 450mA Solar Cell
  2. Portable aquarium aerator
  3. 2 x AA Rechargeable Batteries
  4. Piezo Buzzer
  5. Perfboard
  6. 555 Timer
  7. 3 x 2N3904 NPN Transistors
  8. BD135 NPN Transistor
  9. Heat sink
  10. Capacitors - 470 uF, 0.1 uF
  11. Resistors - 220 ohms, 470 ohms, 2 x 10 k, 100k, 1M.
  12. Indicator LED
  13. Toggle switch
  14. Jumpers

Other materials:
  1. Casing
  2. 3 x 2" Stainless Steel bolts (that will serve as water probes)
  3. PVC pipe and fittings
  4. Miscellaneous tools

Observation, Experimentation and Results

To test the device, I installed it in a small pond where rainwater had recently collected. I waited until mosquito larvae began appearing in the pool to ensure that the pool was suitable for mosquito breeding. About three days after the larvae were born, I installed the aerator in the pond and observed the larval population in the pond. The results of the experiment are tabulated in the image above (I did not provide photos of the experiment as the larval population in the pond was not visible in the photos).

The experiment shows that while the aerator was not sufficiently powerful to suffocate and kill the full-grown larvae, within two hours it wiped out the majority of the young larval population and ensured a mosquito-free water body thereafter.

A Mosquito-free Tomorrow

My observations have shown that, by preventing water stagnation by means of aeration, it is possible to control mosquito breeding and thereby control the proliferation of malaria.

The aeration device that I have built costs less than $ 10. Considering that every year, the global medical expenditure on malaria control amounts to over US$ 6 billion, ubiquitously installing this device in villages and cities would cost only a fraction of that amount.

I hope that, one day this cost effective and sustainable device will save the world valuable money and priceless lives.

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.

16 Dec 2012

How to Make Oil From Plastic (theory)

Among the many irremediable wounds that man is inflicting upon the environment, the improper disposal of waste plastic is growing into an alarming issue of concern. 

Despite its amazing properties of strength, durability and its light weight, plastics have a major drawback: they can take up to 500-1000 years to naturally degrade. So if plastic had been discovered 500 years ago, and if Shakespeare used to brush his teeth, then his toothbrush would still be lying somewhere in England!

Some other issues with waste plastic are that it affects humans, animals and marine life; it causes soil infertility where dumped; and only 8% of all plastic waste is recycled! Sounds a trifle, right! Another lesser known factual reality is that for the production of plastic, 7% of the global crude oil is consumed, which is more than China's total crude oil consumption. 

So what do we do with these ever-growing mounds of plastic waste? Bury plastic underground? Burn it? Or launch it into space! These solutions are more disastrous than the problem itself.


The Japanese inventor Akinori Ito popularized the ingenious idea converting waste plastic back into fuel oil through plastic pyrolysis. Pyrolysis is a thermochemical decomposition of organic material at elevated temperature without the participation of oxygen.

Akinori Ito displaying his
pyrolysis machine for home
In this process long polymer molecules are broken down into shorter chains of hydrocarbons with the help of heat and pressure. Essentially the process is mimicking the natural process by which organic materials are broken down into oil in the nature which takes million of years. The pyrolysis process does this with intense heat in a closed system in a short amount of time. A catalyst can be used to lower the temperature and increase the yield. Other substances which can be pyrolyzed are biomass, waste tire, lubricating oils, coal and petroleum residues; waste tire pyrolysis being the most popular and the most profitable of them all. 

The basic process of pyrolysis goes as follows:

1. Shredding
Firstly, the waste material must be segregated and, if possible, be cleaned. Then it is shredded to speed up the reaction and to ensure that the reaction is complete. 

2. Anaerobic heating 
The shredded material must be heated in a controlled manner in an oxygen-free reactor. One of the most crucial factors in this operation is maintaining the right temperature(~430C for plastic) and the rate of heating, as they define the quality and the quantity of the final product. 

3. Condensation

The gas that comes out from the reactor must be condensed by passing it through a condensation tube or by directly bubbling it in water. 

4. Distillation 

This mixture of oil that you obtain can be used as furnace oil but it isn't sufficiently pure for engines. If you want to use it as engine fuel, you need to extract and purify the desired products from the mixture through fractional distillation. 

Some benefits of pyrolysis are that the process does not generate harmful pollutants and that the by-products can be used as fuel for running the plant. In the case of plastic, some
 of the valuable fuels and solvents that can be extracted through waste plastic pyrolysis are gasoline, kerosene, diesel, benzene, toluene and xylene. And a kilo of waste (typically PP) can yield upto a litre of fuel whereas the incineration of the same quantity of plastic would produce 3 kilos of CO2! 

So through this process of pyrolysis, the bane of abhorrent plastic waste, can now become a boon and a source of abundant fuel. This will reduce plastic in landfills, reduce emissions and be a reliable alternative to the depleting fossil fuels. Don't trash your future. Act now!

14 Apr 2012

Arduino Music Visualizer

Music is food for the soul...I love listening to music and also love electronics. So I thought why not make an Arduino based LED music visualizer! With some cool lights synced with some music, you could create a great effect and a great ambiance! 
That is what I tried in my first Arduino project: an Arduino music visualizer. You can call it what you like: musical lights, dancing lights, etc. With slight modifications in the amateur sketch given below and by replacing the LEDs with more exotic lights, you can create a sensational light show!

Here is the code: 
Arduino LED Music Visualizer (code)

Materials Required:
  • Arduino Uno
  • 8 x 8 LED matrix
  • mp3 male jack
  • wires
Tools Required:
  • Soldering Iron
  • Wire Stripper

Wiring for the Arduino and the LED matrix 
Step by Step Guide:
  • Solder one wire to each column and row of LEDs (that makes 16 wires)
  • Insert the row wires in the Arduino pins A5, A4, A3, A2, 3, 4, 5, 6 in their respective order
  • Insert the column wires in the Arduino digital pins 7, 8, 9, 10, 11, 12, 13 in their respective order
  • Insert the negative wire of the mp3 jack into a ground pin
  • Insert the positive wire into the analog pin A0
  • Write the sketch on your Arduino verify the code and the wiring
This is what the music visualizer I made looked like:


Instead of an LED matrix, you could make an LED cube in this way. Below is the fascinating YouTube Video that inspired me to make my first Arduino project:

With this project, enhance your music listening experience and create a rocking ambiance. 

11 Apr 2012

How to Make a People Counter

This is a very useful circuit and has unimaginable applications. You could use this counter to know how many people enter a mall daily, or use it with a conveyor to count the number of objects made, or with a powerful LASER you could even count the number of vehicles passing at a certain point! Moreover, by replacing the calculator by a stop watch, you could make an accurate automatic stop watch.

Materials Required:
  • An ordinary calculator
  • A powerful LASER
  • 9v Battery
  • 9v Battery Connector
  • PCB
  • 5v DC Relay 
  • LDR (photocell)
  • NPN Transistor
  • 100K Variable Resistor
  • Diode
  • 2 Push Button Switches
  • 2 Toggle Switch
  • Box to keep the circuit compact
People Counter Circuit Diagram
Step by Step Guide:
  • Firstly, solder all the components on a circuit board as indicated in the circuit diagram above
  • Open up the calculator and identify the points for the 'on', '+', '1' buttons 
  • Solder push button switches to the 2 points of the '+' and '1' buttons and a toggle switch to the 'on' button  such that they can be easily accessed
  • Identify the '=' button and solder the relay output to it
  • Cut out openings in the box for the 4 switches coming from the calculator, the toggle switch that switches on and off the entire circuit, the calculator's LCD display, and, most importantly, the LDR
  • Fix the PCB, the calculator and the switches into the box
  • As you want the LDR to be sensitive to the LASER's light and not be affected by ambient light, you need to block all ambient light coming to the LDR and let only the LASER beam to hit the LDR. For this you can fix an opaque tube (e.g. the body of a pen) to the LDR

      Now that the receiver component is complete, you just have set up the system in the desired place. So if you want to know the number of people that enter somewhere, place this receiver box at the trunk level of a person on one side of the door and the LASER on the other side exactly at the same level. It is preferable that the LASER be powered by the mains power rather than a battery as a weak beam of light would not be efficient. 

      Once you have placed the transmitter and the receiver, switch on the circuit and the LASER, press the '+' switch, then the '1' switch. Cut the beam a couple of times and see if the counter detects it. If it doesn't, increase the resistance of the potentiometer until the calculator adds a '1' at the slightest rupture of the LASER beam. Great! you have made your LASER pleople counter, but how does it function?

Let's go through electrical the process:
  • While the LASER beam is falling on the LDR, the latter's resistance remains negligible and the 'base' and the 'emitter' pins of the transmitter are shorted. Thus the relay does not get power
  • While the beam is cut, the LDR's resistance shoots up and the 'base' gets power. The relay goes on.
  • As the coil is charged, it shorts its two output pins emulating that the '=' button gets pressed and a '+1' is added on the display
  • Everytime someone or something breaks the LASER beam, a '1' keeps getting added to your total and you have your DIY LASER People Counter!
This is a simple weekend project that has applications in every field. Use your imagination, finds undiscovered applications for this counter and do write them to me! 

21 Mar 2012

DIY Water Level Controller

This is a project I had to complete within four days in school. It is an extremely reliable water level controller which can serve you for years without giving any problem. Unlike some automatic water level controllers, this system will not damage your pump as it will switch it on only if the underground tank is full. So build this circuit, save water and have fun!

Materials Required
  • 12A Relay
  • 12V 1A Transformer
  • PCB
  • Blue LED, 1 Red LED, 1 Green LED
  • Diodes
  • 1k Resistors
  • 10k Resistor
  • 2200 microfarad Capacitor
  • Toggle switch
Tools Required
  • Soldering Iron
  • Hand Drill
  • Screw Driver
  • Wire Stripper

Water Level Controller Circuit Diagram
Step by Step Guide:
  • Follow the circuit diagram and solder the components accordingly
  • Solder the wires going to the underground tank to the place marked 'UG' in the diagram
  • Solder the wires going the the overhead tank to the place marked 'OH'
  • Solder the relay's coil pins to the place marked 'Relay'
  • Solder the transformer's secondary wires to the place marked 'AC voltage source
  • Drill holes in the box for the power cables to come in and for the 'OH' and 'UG' wires to go out
  • Solder the transformer's primary wires to the live and neutral wires  through the toggle switch
Automatic Water Level Controller circuit

This completes the core circuit of the Water Level Controller. To test your circuit, short the 'UG' wires together and short the 'OH' wires. This should light up the three LEDs. The 'Power' LED indicates power coming to the circuit board, the 'UG' LED lights up if the underground tank is filled and the 'OH' LED lights up indicating that he pump is running. Connect an incandescent bulb ( or any other) and a power source instead of the pump. If everything goes well, the bulb should light up representing the running state of the pump. Next:
  • Lay the 'OH' wires till the overhead tank and the 'UG' wires to the underground tank and connect them to the float switches
  • Solder the live wire and the wire going to the pump to the relay pins
Now, let us go through the entire process... Water is almost finishing in your house. The 'OH' float switch turns on. When the underground tank gets filled, the 'UG' LED lights up, the 'OH' LED lights up, the relay coil gets powered and the pump is turned on. Once the overhead tank gets filled, the float switch in there turns over and the 'OH' LED goes off and the pump is immediately turned off.

So henceforth, you don't have to worry whether you are going to get water in the shower when you go for a bath and you will be also saving precious water without any efforts! 

24 Jan 2012

How to Make an Odometer

This is a really interesting calculator hack and this concept can be useful in diverse projects. If you were looking for a means to find out how much you travel on your bike, then this is just the right place. All you need to spare is a dirt cheap calculator and 20 minutes of your free time. 

Materials Required:
  • A calculator
  • A reed switch
  • A powerful magnet (preferably light and small)
  • A couple of wires
  • And a bicycle :P

Tools Required:
  • Soldering iron and solder
  • Double sided tape
  • Duct tape or any strong tape 

Step by step instructions:
Calculator PCB
  • Open up a calculator and locate the equal sign button on the PCB
  • Locate the 2 holes that are linked to this button (tricky)
  • Take 2 wires of lengths depending on the distance from the calculator to the magnet
  • Solder each of the 2 wires to the 2 holes of the equal sign button
  • Twist the other ends of the wires with the legs of the reed switch and solder both the joints
  • Put back the cover of the calculator and switch the device on.
  • Press the '+' button, then  '1' and then bring the magnet back and forth to  the reed switch and the number on the LCD display should keep increasing by one. If you succeed doing this then your odometer is almost complete!
  • Measure the radius of your wheel and calculate its circumference.
  • Now fix the magnet on one of the spokes of your bike close the axle with some tape.
  • Fasten your calculator firmly on your chain guard (or any other flat surface) with the double sided tape
  • Tape the reed switch as close to the magnet as possible yet at a safe distance from the spokes
  • Again switch the calculator on, press the '+' button, insert the 'circumference' of your wheel preferably in meters and RIDE ON!!
Sorry, I couldn't find a cleaner bike!! :P
Every time the magnet comes close enough to the reed switch, the '=' button is shorted and the circumference of your wheel is added to the distance you have traveled. Your bicycle odometer is complete! 

NOTE: At high speeds the reed switch will not always get triggered by the magnet and the odometer might display faulty results. 

19 Jan 2012

Tilt Sensor Alarm

Some time back I came across an article in a magazine where a boy lost his leg thanks to his habit of balancing on chairs. I thought why not build a tilt sensor alarm for chairs before calamity struck me too. So I came up with this simple tilt sensor circuit which doesn't really need any instructions to build.

Materials Required:
  • A Piezo Buzzer
  • A 9v Battery
  • A 9v Battery Connector
  • A dead AAA battery
  • A small and thin magnet
  • A small box to keep the circuit compact
  • Aluminium foil or any small conductive sheet

Tools Required:
  • Insulation tape 
  • Double sided tape
  • Soldering iron and solder instead of insulation tape

Step by step instructions:

The Tilt Sensor Circuit

A Close-up of the connectors.
  • Scrap off the paint of a dead battery
  • Cut two pieces of aluminium foil of about 1cm X 1cm
  • Connect the positive end of the battery connector to the positive end of the piezo buzzer by twisting the copper strands together or by soldering
  • Fix the magnet on one side of the box as indicated in the images above so that the battery remains stuck to the contact points for a while
  • Stick the negative ends of the buzzer and battery on either side of the magnet keeping in mind their alignment with the rolling battery
  • Stick the aluminium foils on top of the negative ends to improve connectivity on the contact points
  • Arrange the circuit in your box as indicated in the images above and do the necessary for aesthetic beauty :)

Hard Luck for those who love to balance on chairs!

Now you can place this circuit wherever you like and use it as a tilt sensor. Of course the smaller the piezo buzzer, the battery and the rolling element, the more compact the circuit box. Simple as that!