Month: August 2013


When a vehicle is driven on the highway at night, it is required that light beam should be of high density and should illuminate the road at a distance sufficiently ahead. However, when a vehicle coming in the opposite direction approaches the vehicle with a high-beam headlight, driver of that vehicle will experience a glare, which may blind him. This dazzle effect is one of the major problems faced by a driver in night driving. To avoid this impermanent blindness, a separate filament is usually fitted in the “dual-filament” headlight bulb in a position such that light beam from this second filament is deflected both down and sideways so that the driver of the oncoming car is not blinded. In practice, one mechanical dimmer switch is used by the driver to manually select high (bright) or low (dim) headlight beam. However, this is an awkward task for the driver especially during peak traffics.



Our project “Adaptive Lighting System for Automobiles” is a smart solution for safe and convenient night driving without the intense dazzling effect and aftermaths. Adaptive Lighting System for Automobiles needs no manual Continue reading


This simple, wearable circuit uses an operational amplifier (or “op-amp”) chip to convert sound into light. An LM324 op-amp and a transistor boost input from a mini condenser microphone to light a series of LEDs. Watch it blink to the beat of your favorite music.


Components Required

  • Battery, 9V (1)
  • Solder, lead-free (1)
  • Battery snap, 9V (1)
  • Hookup wire, 22 gauge, multiple colors (1)
  • PC board, grid style, with 371 holes (1)
  • Resistor assortment, 500 piece (1)
  • Transistor, NPN, 2N4401 (1)
  • Microphone condenser element (1
  • Capacitor, 0.1 µF ceramic (100 nF, capacitor code 104) (1)
  • Capacitor, 1.0µF non-polarized electrolytic (capacitor code 105) (1)
  • Op-Amp chip, Quad, LM324 (1)
  • LED 5mm (1)

Step #1: Gather the parts


  • The electret microphone element is polarized, so be careful not to reverse the connections. The ground leg is the one with the 3 silver traces running to the case (second photo).
  • To identify resistor values from their color codes, you can use this online calculator.
  • The LM324 chip has four op-amps, but this circuit only requires two of them. Continue reading




LDR-based automatic lights  flicker due to the change in light  intensity at dawn and dusk.  So compact fluorescent lamps (CFLs)  are unsuitable in such circuits as flickering may damage the electronic  circuits within these lamps. The circuit  described here can solve the problem  and switch on the lamp instantly when  the light intensity decreases below a  preset level. The circuit uses popular timer IC  NE555 (IC1) as a Schmitt trigger to give  the bistable action.

The set and reset  functions of the comparators within  the NE555 are used to give the instantaneous action. The upper threshold  comparator of IC1 trips at 2/3Vcc,  while the lower trigger comparator  trips at 1/3Vcc. The inputs of both the threshold comparator and the trigger  comparator of NE555 (pins 6 and 2) are tied together and connected to the  voltage divider formed by LDR1 and  VR1. The voltage across LDR1 depends  on the light intensity. Continue reading




Some of the mosquito repellents available in the market use a toxic liquid to generate poisonous vapours in order to repel mosquitoes out of the room. Due to the continuous release of poisonous vapours into the room, after midnight the natural balance of the air composition for good health reaches or exceeds the critical level. Mostly, these vapours attack the brain through lungs and exert an anesthetic effect on mosquitoes as well as other living beings by small or greater percentage. Long exposure to these toxic vapours may cause neurological or related problems.

Here is a circuit that automatically switches on and off the mosquito repellent after preset time interval, thus controlling the release of toxic vapours into the room. Continue reading



You’re being tracked and not necessarily anonymously. A study last March from researchers at MIT’s Media Lab showed that so-called “anonymized” cell phone data is not so anonymous. The researchers were able to extract specific location information for individuals carrying phones with GPS and location services on. If this concerns you, you might want to keep an eye on New York-based artist and technologist Adam Harvey, who just launched a Kickstarter program to develop phone pockets that shield your phone’s cellular, Wi-Fi, and GPS signals.

According to PopSci, the slip cover is based on the technology behind the electric field-blocking Faraday cage, which protects electrical equipment from lightning strikes. Like the cage, the Off Pocket contains a metal fiber mesh that blocks the wireless signals (frequencies between 800MHz and 2.4 GHz) Continue reading



I am a big fan of garage sales, flea markets, and thrift stores. They are great places to find used parts and materials for your next project. But one problem that I often run into is not being able to test battery powered electronics to see if they work. Because there are so many different combinations of batteries that are used in portable electronics, it isn’t really practical to carry around batteries for testing. One device may need 6 AA’s and another may require 4 D’s. So I came up with this simple pocket-sized variable power supply. It can plug into either a 9V battery or a 12V battery pack. You can then adjust the output voltage to match the device that you want to test and attach the output wires to the end terminals on the device’s battery connectors. This lets you power the device long enough to see if it works.


  • 8-Position DIP Switch
  • 220 ohm Resistor
  • 1 µF Capacitor
  • 0.1 µF Capacitor
  • LM317 Adjustable Voltage Regulator
  • 2 x Alligator Clip Wires
  • Perf Board
  • 9V Battery Connector
  • 270 ohm Resistor (preferably 1/8 watt) (7)
  • Soldering Iron and Solder


Step #1: Materials



  • LM317 Adjustable Voltage Regulator, 0.1 µF Capacitor, 1 µF Capacitor, 220 ohm Resistor, 7 x 270 ohm Resistor (preferably 1/8 watt), 8-Position DIP Switch, Perf Board, 9V Battery Connector, 2 x Alligator Clip Wires, Continue reading



It’s easy to build up a “junk box” of items you can use to build projects seen in just about any-thing you can imagine.

Many of my articles take advantage of found components, often picked out of trash bins. Just because an electronic device has failed at its original task doesn’t mean it can’t perform other tasks. Castoffs can be recovered and the parts repurposed in countless ways.

Recently, my trash-picking adventures turned up a discarded laser printer. I set about finding what wonders were waiting beneath the plastic covers.


My first discovery was the main circuit board. Once I stripped the heat shields off, I found over 50 nonproprietary electronic parts, including capacitors, resistors, voltage regulators, transistors, transformers, coils, and integrated circuits. Jackpot! A couple of boards like this, and you’re on your way to building a backup supply of parts for future projects. A second, smaller PC board also yielded numerous useful components. Continue reading




Click the picture to view the MINI ROVER in action

Ever wanted to explore your house from a pet’s perspective, here’s the Mini Rover Surveillance bot which is going to do exactly that.


Step #1: Strip down the car.


  • Using Scientific Toys’ EZTEC-branded 1:17 scale Chevy Silverado R/C car as a camera platform. This toy is cheap, hacker-friendly, and works astoundingly well for the price.
  • First, detach the truck body shell from the chassis by removing 3 screws: 2 on top, in the truck bed, and 1 from below, between the front wheels.
  • Now, open the electronics compartment by removing 4 screws, as shown, and lifting the plastic cover gently up and off. The floppy wire antenna, which is threaded through a hole in the cover, should slip out the bottom as you do this.

Step #2: Install the chassis standoffs.



  • Position the video camera mounting base on the car’s electronics compartment cover, as shown. Use the base as a template to drill 3 matching 5/32″-diameter holes in the electronics compartment cover.
  • TIP: You may find it easier to operate the drill through the baseplate if you remove the camera mount ball joint at the top of the stem first. Simply turn the wingscrew all the way out and the whole assembly will come off.
  • Turn the electronics compartment cover over, and attach three 10cm standoffs on the top side of the compartment cover using the screws that come with the standoffs. Continue reading




The incandescent lamp provided inside the refrigerators glows whenever we open the door. It suffers from several disadvantages like:

1. Being a single light source, located in the upper corner, light does not spread uniformly. Only upper shelves get good light and the lower shelves are in darkness because of the shadows of food items kept.

2. Ironically, the lamp generates heat in the space which we are trying to cool, thus making the compressor work for longer duration.

3. During power outages, there is no illumination inside the fridge, when it is most needed.

The above problems could be overcome by using a distributed array of LEDs with battery back-up, which provides shadow less light and cool operation.



Fig. 1: Rows of LEDs placed in PVC channels


Fig. 2: Orientation of LEDs and the arrows indicating the direction of light from LEDs

Two columns of six white LEDs in each row (2×6 array of white LEDs) are made using white PVC channels. The length of the channel equals the height of the cooling compartment of the fridge. The LEDs are placed such that each shelf has two LEDs located at the top corner. These channels are placed in the left- and right-hand corners inside the fridge as shown in Fig. 1. Continue reading



This easy-to-build electronic alarm will remind you of an impotant task after a preset time. It is particularly useful for housewives and busy professionals. All you have to do is set the time in minute swith the help of two thumbwheel switches (S3 and S4) and press and release start switch. Precisely after the time set by you is over, there is an audio as well as visual indication to remind you that the time you set has elapsed. The gadget is portable and operates off a 9V battery.

At the heart of this circuit are two counter ICs CD4029 (IC4 and IC5). These are programmable up/down 4bit binary/decade counters belonging to CMOS family of digital integrated circuits. The information present on them is fed to inputs P0 through P3 in parallel. It is loaded into the counter when the PL input is high, independent of the clock pulse input. In this circuit, IC4 and IC5 count in up/down mode when the up/down input is high/low. These have been wired as 4-bit binary counters in countdown mode with B/D input low. The counter advances by one count on every low-to-high transition of the clock pulse. Continue reading

Solar-Powered Laptop Lasts 10 Hours on a Charge


What if it only took two hours out in the sun supply your laptop with 10 hours of battery life? That’s what the Ubuntu-driven laptop aims to do, according to the folks over at WeWi Telecommunications Inc.

The Sol, a rugged-looking laptop with built-in foldable solar panels, is designed for use in the military, education and developing countries where electricity is scarce. The Canada-based makers behind the Sol claim that the device can run directly off solar energy or can harness the sun’s rays to charge the laptop’s battery in under two hours. Once fully charged, the battery is expected to last between eight and 10 hours.

Packing mid-range specs, the Sol comes with a 1.86GHz dual-core Intel Atom D2500 processor with 2GB of RAM upgradeable to 4GB, a 320GB SATA HDD from Seagate, GMA3600 graphics, a 13.3-inch LCD screen with a 1366 x 768 resolution, and a 3-megapixel camera. It also features a USB 2.0 port, an audio jack, HDMI, Ethernet and SD card ports like most standard laptops. Wi-Fi, GPS and Bluetooth will come built-in to the Sol, and it will be available in 3G and 4G LTE configurations as well. The Sol will run for $350 but you can also snag a waterproof edition for $400, and its slated to launch in Ghana, Africa first. Continue reading

Disposable Drones Take Flight


When we think of drones — nay unmanned aerial vehicles — we typically picture military drones or those ubiquitous quadrotors. However, two new mini-drone designs are taking shape: a paper airplane and a maple seed.

a team of roboticists created both designs to help record atmospheric conditions in the event of a forest fire. The disposable, self-steering drones are essentially sensor modules that can be dropped over a forested area to relay environmental data that could indicate potential for fire.

The first prototype looks exactly like a standard paper airplane, only this one’s made of biodegradable cellulose material. Once deployed from a larger aircraft, the so-called Polyplane drone steers itself using tabs attached to the back of each wing. An onboard control system bends each tab to direct the craft as close as possible to a pre-determined landing area. Because the circuits Continue reading

Tick Bot Terminates Those Lil Buggers


What good are ticks? They transmit awful diseases including babesiosis, ehrlichiosis, Rocky Mountain Spotted Fever, Lyme disease and tick paralysis and the critters have been associated with encephalitis. And warmer temps aren’t helping. Insects are cold-blooded, so hot weather makes them more active.

But listen up, ticks. Researchers at the Virginia Military Institute have your number. They’ve built a small rover that mimics a live host to draw you from your hiding places and kill you on contact. Continue reading


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