Category Archives: Technology

LASER scanners for vector projection

I made a LASER projector with DC motors. This can display only circular forms. I wanted to make one that can display vector graphics. There is an instructable to make these from speakers. I am also trying that but my setup has a lot of distortion.

In this alternative I have used the read head of the CD ROMs to move the mirrors and bounce the LASERS to make figures

What you need

Junk CD drives, screw driver star head, small round mirrors, glue and lot of patience.

You need to open the CD drives part by part till you reach the actual lens mechanism.

cd drive

What we need is a the actual read head with all the mechanism built around it.

lens mechanism

This is actually a set of two coils in between two very powerful magnets and it is used to focus the laser and read the CD. One of the coils moves the lens up and down and the other coil moves it left and right.

My concept was as follows.

Apply a constant voltage to push up the lens. Attach a mirror to it. and use the varying High, Low voltage at both ends to move the mirror left and right.

Following are the pictures that I have taken for my setup.

2012-02-05 22.38.59 2012-02-05 22.38.39

2012-02-05 22.46.51 2012-02-05 23.40.45

2012-02-05 22.38.23

The pictures show different views of the lens mechanisms. Wires have been soldered to the coil ends for the ease of connecting it to the microcontroller board. Mirrors have been glued on the lens and the mirror moves with the lens. Following is the video that shows these in action.

Following pictures have been taken after the setup was done and the microcontroller was programmed to move the mirrors.

I am able to draw something but one of the heads seems to be having some issues as it is creating a lot of distortion.

2012-02-06 00.21.08  2012-02-06 00.21.37

2012-02-06 00.12.43  2012-02-06 00.15.23

2012-02-06 00.55.21  2012-02-06 00.56.44

The pictures show the setup on a cardboard box wit the LASER. A small paper screen has been setup to have a look at the drawing. I was successful in drawing a horizontal and vertical lines. Slanted lines have some distortion and a lot more distortion is noticed when drawing characters.

I will be working on a more stable version and will post all the updates when it is done.

Arduino–breadboard hookup

I have been facing lot of issues with so many hookup wires running between the breadboard and the controller board. A small shake at times dislodges the cables and things stop to work. This inspired me to make hookup cables which do not get dislodged with small shakes and movements.

This is what it looks like

2012-02-06 15.43.08

This is a nice rugged setup when a lot of cables need to run between the arduino and the breadboard.

I made these because I could not find male to male jumper with headers for cheap. This works good for me and was made from the spares that I had lying around.

These can be made in a couple of minutes.

Parts needed are: ribbon cable, male headers, solder wire and soldering iron.

2012-02-06 15.39.15

Cut out desired length of ribbon cable in group of 6. Arduino has output in group of six. This will work for any other board too just the number of wires that are to be kept together will be different.

Clip the make header pins in group of 6 and solder to each end.

And you are good to go.

To make the soldered ends more secure i taped the solder joints with foam tape from both ends. This way the solder points dont hurt the fingers and also the joints are kept intact and are insulated too.

2012-02-06 15.40.21 2012-02-06 15.43.23

Unobot 1–My First Bot


My first obstacle avoiding bot based on the tutorial by Community of robots.

This is my first one and helped me learn a bit about sensors, feedback and servo operations. One difference in mine is the use of IR proximity sensor which I had lying around instead of the Sharp distance sensor.

This one does not measure distance and just detects the obstruction. That is why if it has a obstruction on both left and right it turns right. Idealy it should turn towards the farther one.

This one has been made from simple L293D based driver on a breadboard and DC motors on a half chassis of a line follower bot Smile

The code is the exact copy paste from the tutorial just to see if this thing works and it did, you can see in the vdo below. Would be making some changes to the structure and the software and post soon.

LASER Projector

laser circleI was fascinated by LASERs when I first went to IIT Kanpur during my school days. Since then I have been reading / playing a lot with LASERs. My first one was a LASER trip wire and then a LASER pattern generator. It all was around 10 years back. Having recently acquired an Arduino UNO a plethora of options have opened up. I have started to learn from the beginning and this time I have the power of a microcontroller with me. !0 years back these things were hard to find and were freaking expensive and I didn’t have a sponsor 😛

Now I play around with stuff and fund my own projects. I have recently made a dice and a digital thermometer just to learn the new way of doing it.

Next was this LASER Projector (pattern generator to be precise). It involves two DC motors and L293D as a motor driver.

I customized the Motor driver circuit for speed control with Arduino PWM.

The table shows the connection details.


Two push buttons were added to control the speed of one motor. The other one rotated with a constant speed. One PWM pin was used to control the LASER as it gets too hot when switched on continuously.

The photo below shows the setup (Not very neat though)


Source code


int motor1pin1 = 5;  //define digital output pin no.

int laser = 12;  //define the pin for laser output PWM.
int motor1pin2 = 6;    //define digital output pin no.

int speedpin1 = 3;     // define analog output pin no.

int motor2pin1 = 9;                  //define digital output pin no.

int motor2pin2 = 10;    //define digital output pin no.

int speedpin2 = 11;   // define analog output pin no.
int up = 1;  // define pushbutton pin no.
int down =2; // define pushbutton pin no.
int factor =32; //define speed control variable

void setup () {
pinMode(motor1pin1,OUTPUT);        //set pin 3 as output

pinMode(motor1pin2,OUTPUT);        // set pin 4 as output

pinMode(motor2pin1,OUTPUT);        //set pin 3 as output

pinMode(motor2pin2,OUTPUT);        // set pin 4 as output



void loop () {



Arduino – 7 segment Dice

I have been waiting to play with embedded programming since and recently ordered an Arduino. I tested the spare LCD and displays with the normal tutorial commands and went step by step remeber the thing about slow and steady!

I want to build a vector LASER projector and a quadrocopter someday but that is too far. It is kind of my VISION. My Mission is to learn embedded programming via arduino.

It is one hell of a kit.

My very first experiment was a 7 segment dice.

It is a very simple project. Doenst require much and all the thing were in the kit that I ordered.

Still following is the list of what I used:-

  1. Arduino Uno
  2. 7 segment display RED
  3. Breadboard
  4. Jumper wires
  5. Push Button switch

The schematics for the display and Arduino I/O used by me are as follows

Arduino Pin 7 Segment Pin Connection
2 7 (A)
3 6 (B)
4 4 (C)
5 2 (D)
6 1 (E)
7 9 (F)
8 10 (G)
9 5 (DP)

I used a normal routine from one of the websites to cycle through the numbers 0 to 9.

Then I reduced the delay to have the numbers roll faster and faster.

Then I reduced the count from 9 to 6 (a dice has only till 6 and 0 was left just for fun).

Then I added a push button and added in the code to detect the state of the button.

When the button is pressed the state of the pin goes LOW and at that point I had programmed the loop to display the dot and pause for 2 seconds.

CATCH: The numbers scroll so fast that all we see is scrolling segment. And when the button is pressed the current number just paused for 2 seconds and then it starts again.

No random number generation 🙂

Video of the thing in action

source code (modification of sample code)
// Arduino 7 segment display example software
// License: (Go crazy)

// Define the LED digit patters, from 0 – 9
// Note that these patterns are for common cathode displays
// For common anode displays, change the 1’s to 0’s and 0’s to 1’s
// 1 = LED on, 0 = LED off, in this order:

//                                    Arduino pin: 2,3,4,5,6,7,8
int inPin = 1;
int val = 0;
byte seven_seg_digits[10][7] = { { 1,1,1,1,1,1,0 },  // = 0
{ 0,1,1,0,0,0,0 },  // = 1
{ 1,1,0,1,1,0,1 },  // = 2
{ 1,1,1,1,0,0,1 },  // = 3
{ 0,1,1,0,0,1,1 },  // = 4
{ 1,0,1,1,0,1,1 },  // = 5
{ 1,0,1,1,1,1,1 },  // = 6
//{ 1,1,1,0,0,0,0 },  // = 7
//{ 1,1,1,1,1,1,1 },  // = 8
//{ 1,1,1,0,0,1,1 }   // = 9

void setup() {
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(inPin, INPUT);    // declare pushbutton as input
writeDot(0);  // start with the “dot” off

void writeDot(byte dot) {
digitalWrite(9, dot);

void sevenSegWrite(byte digit) {
byte pin = 2;
for (byte segCount = 0; segCount < 7; ++segCount) {
digitalWrite(pin, seven_seg_digits[digit][segCount]);

void loop() {
for (byte count = 6; count > 0; –count) {
val = digitalRead(inPin);
if (val == LOW)
sevenSegWrite(count – 1);


Android in Space

On the last manned space shuttle, Atlantis, NASA sent two Nexus S phones along for the ride as part of the STS-135 mission. The goal is to use Nexus S on the International Space Station to explore how robots can help humans experiment and live in space more efficiently.

NASA is using Nexus S phones to upgrade a trio of volleyball-sized SPHERES (Synchronized Position Hold, Engage, Reorient, Experimental Satellites), originally developed by MIT. The phones help the robotic satellites perform tasks the astronauts used to do, like recording sensor data and capturing video footage. In the future, the phones will control and maneuver the SPHERES using the IOIO board and possibly the Android Open Accessory Development Kit (ADK).

source Google

The Guardian and Observer Kindle edition is now available

Click here to download a 14-day free trial from

Kindle edition

The Kindle edition of the Guardian. Photograph: Graeme Robertson for the Guardian


he Guardian and Observer Kindle edition is now available for download seven days a week in the UK, US and more than 100 other countries. It carries the content from that day’s newspaper, including all the editorial sections and supplements:

• Top stories, UK, international and financial news
• Comment, editorials and obituaries
• Reviews
• Sport
• G2 (Monday to Friday)
• Weekday supplements Film & Music, Education and Society
• Weekend magazine and supplements, including the Guide and the literary Review (Saturday)
• Observer magazine and the New Review (Sunday)
• Observer Food Monthly (one Sunday each month)

Many articles are supported by images, and the editions benefit from the Kindle’s easy to navigate layout.

Click here to visit the Kindle store and download a 14-day free trial. Once your trial period has ended, pricing will be as follows:

UK: £9.99/month, £0.99/issue
US: $9.99/month, $0.75/issue
Rest of world: $17.99/month, $1.99/issue

A full explanation of how to download content for your Kindle and other useful information is available from Amazon.


Digital Living in 2 steps with DLNA

  1. First you need a home network — wired or wireless — and you’re ready to get started. That’s because DLNA Certified devices today connect, discover and communicate with each other over a home network, like the one you might already have for sharing your broadband Internet. (There might be other ways to connect in the future.)
  2. Next, go and buy the new DLNA Certified products available on the market today, and many more that will be available soon. Once you have those connected to your home network, and there are numerous possibilities…

The Possibilities

If you own two devices, you want them to be compatible. The same is true for three devices, or four or ten.

DLNA Certified® products are built to work together, even though they come from many different companies. Finally, you have the freedom to choose the DLNA Certified device that’s right for you, regardless of the manufacturer, and to create a digital network that fits your life.

Here are just a few examples of what’s possible with DLNA Certified products:

  • Watching home movies

    PC to network attached storage to television

    You recently downloaded your daughter’s birthday party video from your digital camcorder to your PC, and stored it on your DLNA Certified network attached storage (NAS) drive. Now you want to share it with your parents who are visiting. Step one: Use the TV’s remote to call up the video on your DLNA Certified TV. That’s it. No step two.

    Before DLNA: You probably had to burn a DVD of that video, taking hours, or you had to hook up the camcorder to the TV to watch it, fiddling with messy cables that are never where you thought you put them.

    Watching home movies

  • Listening to music

    PC to network attached storage to television

    It’s your monthly poker night and you want the guys to hear all the music you’ve copied onto your DLNA Certified PC. Your computer’s speakers are in the office, so send the songs from your PC to your DLNA Certified home stereo in the family room.

    Before DLNA: You probably had to burn CDs of your playlists, taking hours, or you had to hook up your portable music player to your stereo.

    Listening to music

  • Watching photo slideshows

    Mobile to television to network attached storage

    You can’t wait to show everyone the shot of your son’s game-winning goal captured on your mobile phone. With a DLNA Certified phone, just send the pictures to your DLNA Certified TV to relive the goal in all its triumphant detail. Then send the photo over to your DLNA Certified network attached storage (NAS) for safe keeping.

    Before DLNA: You would’ve been out of luck if you wanted to show your photo on anything other than your mobile phone’s tiny screen.

    Watching photo slideshows

  • Enjoying music

    PC to mobile phone

    You want to get some music together for your family road-trip to Niagara Falls. You’re going to let your teenage son choose some of it, but you want your own tunes, too. So, from that same DLNA Certified PC on which your music is stored, you send your favorite songs to your DLNA Certified mobile phone to take with you.

    Before DLNA: Burning CDs of your road-trip playlists would just take too long, so you’d end up having to endure your son’s music.

    Enjoying music on-the-go

  • Watching TV shows

    DVR to television

    You’ve been waiting all day to watch last week’s episode of your favorite show stored on your DLNA Certified DVR. But the kids have commandeered the family room for a marathon gaming-fest. With digital living, you just get the show from the DVR, and send it to the DLNA Certified TV in your bedroom, where you can enjoy it in peace.

    Before DLNA: You might as well join the gamers since the only way to watch a recorded show was on the TV connected to the DVR.

    Watching TV shows

  • Printing photos

    Mobile to television to printer

    Your coworker just sent your phone a hilarious multimedia message photo of himself in Las Vegas. After sending the photo to your DLNA Certified TV to view it on a large screen, you know you have to share it with everyone at work. With DLNA Certified devices, just print the photo to your DLNA Certified printer, with a few simple clicks from your phone, and you can make copies for the whole office.

    Before DLNA: The only way to print photos was to get them to the PC first. And good luck figuring out how to do that from your phone.


You already know something about digital living. There’s the TV and digital video recorder in your family room. (And another set in your bedroom.) You have a PC and digital printer in your office, along with a network attached storage device. And you’ve copied all your music onto your portable music player and haven’t had to open a CD case for years
Then there are the devices that go where you go, like your mobile camera phone, digital camcorder and laptop. All from the best brands.

The compatibility challenge

But something’s missing. Why is it still so difficult to send digital content from one device to enjoy on another device?

Take video for example. It can be a real challenge to get it from your PC to the large flat-panel TV in your living room. You need to download the video from your digital camcorder to your PC, burn it onto a DVD (with complicated software) and then hand-carry it to the DVD player attached to your TV.

It can take hours. And in the end your DVD player might not even be able to read the DVD format you chose. Try it with products from different manufacturers and you might just want to skip it altogether.

DLNA Guidelines: building your network

Digital Living Network Alliance (DLNA) is helping put an end to that frustration. A collaboration of the world’s leading consumer electronics, PC and mobile companies, DLNA has created design guidelines for a new generation of DLNA Certified products that can work together — no matter the brand.

In the DLNA defined future, you’ll buy DLNA Certified products that help you share and enjoy your digital content where and when you want, at home or on the road, by yourself or among friends.

For unified communications, a future unclouded IT industry is prone to get enthusiastic about emerging technologies. In many cases, this has the positive effect of driving support for technologies that go on to make a tangible difference to business performance or, in some cases, people’s lives.

But by the same token, this enthusiasm sometimes has the unintended consequence of hurting a technology’s chances of being taken seriously. We are all too familiar with Gartner’s Hype Cycle. Unified communications and collaboration (UCC) technologies have over the years suffered from being overhyped.

This year, some are claiming unified communications will come of age. So why should this year be any different from previous false starts? The answer lies with another emerging technology that has suffered from its own share of hype: the cloud.

Read the full article by Sudhir Narang – MD BT India