Thursday, 8 November 2012

$35 Computer - Raspberry Pi

Don't confuse it with recently released Hindi film Life Of Pi, I am talking about 'Raspberry Pi', a 35 dollar computer. This is credit card size and weight just 45g, it's computer that you can carry in your pocket if you like. It runs on Linux and powered by 1 GHz ARM CPU.

Specification: 1 GHz ARM CPU, 512 MB RAM, 2 USB Port, 1 Ethernet Port, 1 HDMI Port (to connect with LCD/LED TVs), 1 RCA Video port, 1 Audio Port (these two port can be used to connect it with old generation TVs), 1 SD Card Slot and 1 mini USB port for power supply. 

There are two versions of Raspberry Pi type A and type B. It comes with 1 GHz ARM CPU  and 512 MB RAM, ARM is the same CPU that runs on most of the smart phones. The picture and specs above is for Type B Pi that cost 35 USD. Cost of Type A is even lower only 25 USD, it comes with 1 USB, 256 MB RAM and No Ethernet Port. 

Why it is so cheap?
This computer is designed by Raspberry Pi Foundation a UK registered charities. The computer on offer for 35 USD is what you see in above picture. Yes there will be no key board  mouse, monitor, power supply or even a case. But that's ok, you can use your mobile's power supply to power Raspberry Pi (minimum requirement 1A and 5V) and other accessories lying at home (keyboard, mouse etc). You don't need a monitor as you can use your home TV as a monitor. Of-course there is no Hard disk, the machine boots from a SD Card and it treats SD card as hard disk. If required an external USB hard disk or USB Stick can be used for extra memory. You can buy a Pi case, Power Supply, Keyboard, Mouse and USB Wifi for about same cost as Pi, in total for 70-80 USD you can have good working computer. 

Raspberry Pi comes with 26 GPIO (General Purpose Input/ Output) pins, these pins can be used to make many interesting electronic projects. GPIOs pins can be used to connect and control (via program running on Pi) external devices like temperature sensor, motion sensors, robots, motors etc. For more on GPIO see wikipedia ttp:// &

Some of the projects that immediately comes to mind are

a) Personal Whether Station: You can make your own whether station by connecting temperature and/or humidity, wind sensors and record the reading periodically. See it on your computer or publish it on Internet may be your personal site or a blog.
b) Security Solution: If you want to be more adventurous think of using Pi to control the TV and lights of a home over the Internet or put it on auto-mode. This way you can keep the burglars away when you are on holidays by simulating your daily lights and TV routine. 

I think it is a perfect toy for any 10-15 years old, particularly if you want to inspire them towards the fields of electrical/electronics/ computer engineering. Also not a bad options if you want to develop a hobby around electronics. 

MagPi - A free monthly magazine that covers interesting set of topics like Pi based projects, Linux Tips, PythonPit (to lean Python), The Scratch Patch (to learn Scratch, a Lego like programming language developed by MIT for kids), The C Cave (to learn C). The magazine's look and feel is designed for kids.

My Five Favourites Pi Projects.
1) Media Streamer/ Server: Put XBMC on Pi and it becomes your media streamer/server similar to a Apple TV or Android TV. To know more read my blog

2) Drive a Remote car with Pi, so instead of pressing button on remote a program on Pi can control the car. Refer for more details. This is how probably a future driver less car might be built with a computer, GPS and lots of sensors (i.e. proximity, light, rain sensors etc)

3) Internet Radio, see these links for some ideas.

4) Home Automation, how about switching on your Microwave with phone so that when you arrive at home your rice in microwave is ready. Refer pg 8-9 of Issue 8 (Dec 2012) of Mag Pi

5) Advertisement Solution: Turn your TV in Shop/Factory into an advertisement console. It can be used to advertise about your other business or your friends business. Refer this link to know more about this solution.

Is it available in India?
Yes it is, however please be aware there are only two official store for Raspberry Pi, RS Components and Farnell (element 4), click on the link for their Indian web site. See this discussion thread for more details on other options for India.

For more details visit Pi website -

* The ARM CPU that comes with Pi is 700Mhz only, however it is possible to push its speed up to 1GHz using simple configuration option

My Adventure in 3D Printing

My 3D Printer - RepRap Huxley

** click on any image if you want to see a large high resolution picture
Machine Specification

- Build volume: 140x140x90mm   
- Overall size: 260x280x280mm   
- Printing materials: ABS, PLA, 1.75mm diameter thermoplastic.   
- Build surface: PCB-heated bed to reduce complexity of assembly and to ensure parts do not warp.   
- Computer interface: USB   
- Accuracy: 0.1mm   
- Resolution: 0.0125mm   
- Building speed: 1,800 mm/min   
- Moving speed: 12,000 mm/min   
- Deposition rate: 33 cm3 / hr

I built this machine in April/ May 2012, this is an opensource machine and build instruction are available here The enclosure for electronics (see top center in between those black motors) and stand for the filament spool is printed at home using the printer in picture. All white plastic parts of the printer can be printed using this or similar RepRap printers. If you are concerned about the look of the printer, it is looking so because it was designed that way so that anybody in the world could make it at home. Most of the parts you could find in your local h/w shop except electronics and hotend (part that melt the plastic filament and extrude a thin layer of plastic). If you are electronic and mechanical geek and have access to required tools you can make the electronic controller board and hotend also all by your self. 

Following items are made using this printer, some of them are also shared on Thingiverse ( Thingiverse is an opensource 3D model library, you can download any model from this and print it using a 3D Printer, that means it is not must to know how to design a 3D model. Though 3D designing is not so difficult and you can learn it yourself with some effort, I will share a post on this subject later. Don't forget to visit the thingiverse for some really amazing 3D models. 

Boat with Rubber Band Propeller

I saw a similar wooden boat in London Maritime Museum souvenir shop. The design looked simple and doable to me so I tried and here it is. Kids are very happy with it. The hole in the front can be used to plug a flag, though i yet to make one.

You can download the model from here

Hotwheel Track Connector

I have two hotwheel track toys one with single loop and one with straight track with uphill connector at the end. There was no connector to connect the two tracks but kids wanted to connect them some how. So I designed and made one using RepRap 3D Printer. 

The connector design was derived from other hotwheel connectors. 

You can download the model from here

8mm Triangle Key 
This is 8mm Triangle key used for tool box and any other door which doesn't needs to be as secured as main house door. I wanted a key for my electric and water meter door, i used to borrow it from concierge. Once I thought why not make one using 3D Printer and also learn some design skills.

A hold in cylinder is of triangle shape unfortunately not visible in this picture. For more pictures and to download a model visit

Cone shape Lamp Shade

I broke the original glass shade and manufacturer has stopped producing the particular model.

I thought if Jay Leno (CNBC night show presented) could print car engine parts for his vintage cars, I could at least attempt to make lamp shade for my naked lamp. 

Designing took < 30 minutes and printing about 2 hours. 

 if you want to learn more about Jay Leno's 3D Printing adventure see this

D20 - A dice with 20 sides

Not sure for what game this dice is used for, I thought it could be used to introduce numbers to kids, isn't it a fun way of learning numbers. Roll a dice and ask what number is this?

I printed it with white plastic, all white wasn't very appealing so did the color with permanent marker. Not looking great but serves the purpose. 

The model was downloaded it from here

See this guy has printed it using dual head and two color green and white, looking really nice.

Name Plate

I was using a permanent marker to write a name on this plastic lunch box. This exercise has to be repeated every 10-15 days as name would disappear due to daily wash. Designed and made this small name plate and stick it with feviquick - a long lasting solution. 

3D Printing - What is it?

How about a custom made mobile/tablet case with carving of Taj or any of your favourite pictures on backside. Do you prefer having a stature of your inspirational figure instead of a photo frame on your table? 3D Printing makes it possible to make such custom made object much easier compare to current manufacturing processes, infect you can make such object at home with a desk top 3D Printer that cost just few hundred dollars.

Architect can now make models in mater of hours rather than weeks or months. You can make an informed decision on home interiors based on model and need not wait for 3 months till a carpenter make it and then regret as the actual furniture isn’t similar to what you visualized based on 2D design on paper. Also you could make a toy for your kids at home or make and replace a broken plastic part of mixer grinder, tv, music player or car parts.

What is 3D Printing/ Printer? Like the printer that we use today that takes the soft copy of document or images as an input and print it on paper. A 3D Printer takes a 3D design file of an object and builds it layer by layer and in matter of few hours you can touch and feel the real object in your hand. As of today 3D Printers are capable of creating any object using plastic, nylon, ceramics and metals (i.e copper, silver, titanium). Other limitation is the size of the object it can print; most 3D Printers could print around 10x10x10 inches object. There are printers that can do large print but it can cost significantly higher. Well, it is always possible to print the larger object in part and then assemble it.

3D Printing is about 25 year old technology used by few large manufacturers in aerospace, automobile and few other industries. Also knows as Rapid Prototyping or Additive Manufacturing process as it builds the object layer by layer and mainly used for product prototyping. About 10 years back most 3D printer used to cost > 100K USD, accessible to only large companies. However in last five to seven years because of open-source project like RepRap the price has dropped drastically. The RepRap project has made it possible for SMEs (small and medium scale industries) and even individual to buy a personal 3D Printer today.

How 3D Printer works?
A printer capable of making plastic part will take a plastic filament (1.75mm or 3mm) as source material and melts it to produces very thin wire of size 0.4mm to 0.1mm and layers it as per the shape of the object one on top of the next layer and make a real usable/prototype object. This technique is knows FDM (Fused Deposition Modeling) or FFM (Fused filament modeling).  Some printers use material in powder form and uses laser or adhesive to bind it to create thin layer, it makes multiple such layers to create the final object. The FDM is relatively a low cost technology compare to other techniques.  The RepRap open source printer uses the FDM technology.

How much it cost?

There are two factors that decide the cost of a 3D Printer its capability to handle the material (plastic, resin, nylon, metal or ceramics etc) and size of build platform (decides the max size of an object). For example a printer that can print plastic parts cost much cheaper compare to the one that can print metal parts. Commercial printer using plastic material and build platform between 6x6x6 to 10x10x10 inches cost around 10-30K USD while a RepRap printer cost just  500 to 3000 USD. It seems like open source software, trend for open source manufacturing is slowly picking up. See this video to know more on open source h/w and use of RepRap for bio-printing. 

3D Printing Process flow
      (1)   Design an object using 3D design s/w or download it from the internet
      (2)   Slice the object using Slicer s/w, that create thin slices of 0.1 to 0.4 mm
      (3)   Feed the Slicer o/p file (gcode) to 3D Printer and Print an object

Here are some examples of what is possible with 3D Printer?

  • An Architect can print their design in matter of hours that helps them sell their ideas to customer
  • 3d Printed plastic models are robust and durable that can help builders carry their model to property shows across cities and countries

  • Doctors using it to make the 3D model of the complex surgical procedure like operation of a conjoined twins. The printed model is used for practice and discussion with other doctors to figure out the best procedure for operation.
  • Most hearing aid mold are printed using 3D Printer now days
  • It is used to create custom orthopedic implants (i.e. prosthetics, knee cap etc.) and dental implants like crown, bridge and caps

  • 3D Printer allows students to develop tangible design and engineering skills
  • Many working model or miniature of large machines like lathe, wobbler engine etc. It can be of great help to student in understanding the concepts and innovation. See these videos of 3D Printed working model of Printed Lathe, Wobbler Engine, Planetary gear set, Steam Engine,V8 Engine
  • 3d printer is a perfect innovation tool that empowers everyone to put their design ideas to something tangible.
  • it is used for Jwelery design, it is possible to print silvery jewelry as of today
  • It is possible to print Chocolate or Cake using a 3D Printer
  • Designers have made 3D Printed Bikinis too, do google if you want to see a picture J
  • In London 3D Print show, a band had perform using 3D Printed musical instruments
  • Take a scan of anything and print it yourself for example your favorite sculpture in museum, a toy or a broken car part

  • US Army has developed mobile lab equipped with printers, so that army can print required parts on the field without waiting for it to be shipped from US. US has already deployed one such lab in Afghanistan.

What lies in future?
-          Manufacturer may ask you to download the part design and print it yourself or get it printed from local print-lab
-          Nike may offer you custom made shoes that gives you 100% comfort fit
-          You may not buy Fisherprise toys from department store (i.e. Shopperstop or LifeStyle), instead buy a design from and get it printed locally
-          It might be possible to print the complete iPhone including electronics
-          Printing of human organs like liver or kidney,
-          NASA is exploring the use of 3D printer in space, so that Astronauts can print required parts in space and don’t need to wait for next shuttle

if you like this blog and want to know more about 3D Printing and other interesting technology stay tune.