Friday, 30 March 2012

Prototyping

For the next step in my little electronics project I was looking at adding in the LCD to the display the output, I've selected an I2C device so that it requires very little wiring and also does not need a lot of I/O pins on the Arduino. The I2C bus also requires minimal components, basically a couple of resistors to pull the bus high. However I'll also need to wire up a few components when I come to hook up my rotary sensor (aka mouse) so it made sense to take the approach of having a simple shield to wire everything together.

The arduino protoshield kit seemed an ideal starting point as it had the headers to wire up the digital inputs and outputs and an area to layout components and a few components to wire up some simple circuits.

Protoshield Kit

There are some really nice design features of the PCB such as mirroring the reset switch and ICSP pinouts as those are blocked by the position of the shield. There is also an area for prototyping with SMD chips as well as a for chips in DIP format.


You can download the schematic and Eagle PCB design files from the Arduino site:

http://arduino.cc/en/Main/ArduinoProtoShield

Given that the kit came with red, yellow and green LEDs I could not resist making a simple traffic light. So I wired up the three LEDs with the supplied 220ohm resistors and put together the following simple programme. Obviously if you were programming a real traffic light you'd want to put in bigger delays and also look at adding traffic sensors etc. I'd also suggest switching from this simple structure to something like a finite state machine.


  • /*
  • Traffic Lights
  • Three LEDs wired to digital outputs as specified below
  • */
  •  
  • const int Green = 8;
  • const int Amber = 9;
  • const int Red = 10;
  •  
  • void setup() {
  •  // initialize the digital pin as an output.
  •  pinMode(Green, OUTPUT);
  •  pinMode(Amber, OUTPUT);
  •  pinMode(Red, OUTPUT);
  • }
  •  
  • void loop() {
  •  digitalWrite(Red, HIGH);
  •  delay(1000);
  •  digitalWrite(Amber, HIGH);
  •  delay(1000);
  •  digitalWrite(Red, LOW);
  •  digitalWrite(Amber, LOW);
  •  digitalWrite(Green, HIGH);
  •  delay(1000);
  •  digitalWrite(Amber, HIGH);
  •  digitalWrite(Green, LOW);
  •  delay(1000);
  •  digitalWrite(Amber, LOW);
  • }



I'll remove these temporary components before connecting up and writing code to interface to the LCD, so hopefully more on this project soon.





Repair Manifesto from 1831

A comment about Joshua Field (partner of Henry Maudslay) by James Nasmyth from when they both worked at Messrs. Maudslay, Sons and Field of Lambeth.

"One point he often impressed upon me. It was, he said, most important to bear in mind the get-at-ability of parts - that is, when any part of a machine was out of repair, it was requisite to get at it easily without taking the machine to pieces"

Joshua Field

This reminds me of some of the comments in the Self Repair Manifesto who demand a right to be able to access and repair items.

From James Nasmyth, Engineer: An Autobiography (Cambridge Library Collection - Technology) also Kindle version

Wednesday, 28 March 2012

Origins of the factory

Whilst doing a bit of reading I discovered that the term "Factory" is actually a shortening of an older word "Manufactory" which was in use in the 1800s. The Miriam Webster dictionary states that the first known use of that word was in 1641.

My uncle who is a bit of a linguistic expert added a little more and provided the origins of the word "Manufactory"

"Latin manu meaning by hand and factory coming from factum meaning made"

This is interesting as it's modern usage implies automation rather than hand made.

Additional reference:

http://en.wikipedia.org/wiki/Soho_Manufactory

Thursday, 22 March 2012

Hobby Welding and Duty Cycle

Earlier this month I wrote up a detailed article on duty cycle for Westermans.



For the hobby welder I've really not found it to be an issue. There are a few reason for this. Firstly, I work in smaller sections of steel so only use low current. This means I am well within the rating of my machine. The second reason is that the items I've been making have effectively just been tacked together so no long seams to weld. The last is the nature of the items I've been building, taking the garden obelislks as an example, they required each end of a bar to be welded into place. Between welding each bar there was time taken with moving the frame and fitting the next part into my simple jig. So the welder had plenty of cooling time.



Often the little transformer based arc welders "buzz boxes" that can be bought from discount supermarkets will have very low duty cycles. However, if all you plan to use it for is to weld the hinges back on your gate, then that will be fine.

So as a DIYer or hobby welder you might find youself like me and can live with a lower duty cycle.

Thursday, 15 March 2012

Naomi Press - Solo II - Cavendish Square

The latest City of Sculpture installation has arrived in Cavendish Square. Naomi Press' Solo II is a 3m tall abstract made from stainless steel and is proving a popular picnic spot with the local office workers.

Naomi has been working with stainless steel since 1983 but is also an accomplished artist in other materials with recent exhibitions such as the English Heritage Brick series and Citadel Series in terracotta brick and resin.







Her other sculptures can be seen at the Bermondsey Project Space.

Website: naomipress.com
Photos of the installation and welding into place
Naomi Press : Retrospective A feeling of lightness


Friday, 9 March 2012

The Shed Magazine

The Shed Magazine is a publication from New Zealand, it's just the kind of thing I like to read and I've previously ordered back editions from their website.



"The Shed magazine is for all those people who have or aspire to have their own workspace. And to those who wish they could spend more time in their sheds. Sheddies come from all walks of life: professionals, tradespeople, students, artists, innovators. They have one thing in common the desire to turn a vision into something tangible. They all like to create. The Shed helps to bring together this diverse community to share techniques, ideas, information and news. The Shed covers engineering, woodworking, woodturning, plastics and everything in between. Its subjects are as diverse as its readership but it is always, challenging and inspired."

In the latest edition:

A test of compound mitre saws
Sealander Terry Roycroft’s floating car
Time for a milling machine?
How to make jandals
Introducing Arduino

Subscriptions and back editions can be ordered from their website and are a good price but due to the P&P being more than the cost of the magazine total for a single edition comes to just under £10. However there is an online edition of the magazine for a much smaller cost and there's also lots of free info on their website.

Friday, 2 March 2012

A little venture with electronics

The chaps from Farnell Element14 have kindly sent me an Arduino Uno to have a look at and experiment with.

When the package first arrived, I assumed it was something else as it was no bigger than a pack of cards. However I unwrapped it and yes it was indeed an Arduino Microcontroller.



When you get it open there is a small leaflet explaining what you have bought and the Arduino Uno itself. The packaging points out that the Arduino is made and tested in Italy. And quite rightly too, Arduino is a great Italian success story and counters the current bad press that countries like Italy get in the financial press. The Arduino Uno is just the latest in a range of boards from some rather smart chaps who wanted a board that was cheap and open source for teaching students about microcontrollers and programming. You'll also find a sheet of stickers in the box, which you can put on your project once you've finished it.



What I like about these boards is that they are pretty much ready to go out of the box. The one thing you do need to provide (other than a computer to programme the board) is an A-B USB cable.



You also need to download the software from the Arduino site. And if you are on Windows you will also need to install a driver.

My previous ventures with working with computer control included a GCSE project to build an X-Y plotter controlled from a ZX Spectrum. I initially did not understand that the ports on the back of the Spectrum were directly connected to the main bus. I wired up a switch and when I pressed the memory chips were fried. Once those were replaced, I purchased a proper I/O adapter and got my stepper motors and solenoids wired up just fine. My later ventures were not much more successful, I wanted to build some Knight Rider style lights for a custom PC case so got hold of a PIC and built a PIC programmer. The code worked fine in the simulator but I could just not get it to run on the hardware so that project was abandoned and I just wired the LEDs together instead and had a big flashing bar.

Given these previous projects, I thought it wise to read "10 ways to destroy an Arduino" before getting started. I also watched some of Jeremy Blum's tutorial videos on the Element14 Arduino group. I discovered to my joy that the designers had cleverly wired up an LED to pin 13 on the board so I did not even need to have any additional circuitry to get going.

LED wired to pin 13 - Orange light on the left hand side

The are a range of examples provided with the install so I fired up the blink code and had a play with getting it uploaded and tweeking the values to flash the LED in different rhythms.
  • /*
  • Blink
  • Turns on an LED on for one second,
  • then off for one second, repeatedly.
  • This example code is in the public domain.
  • */
  •  
  • void setup() {
  •   // initialize the digital pin as an output.
  •   // Pin 13 has an LED connected on most Arduino boards:
  •   pinMode(13, OUTPUT);
  • }
  •  
  • void loop() {
  •   digitalWrite(13, HIGH); // set the LED on
  •   delay(1000); // wait for a second
  •   digitalWrite(13, LOW); // set the LED off
  •   delay(1000); // wait for a second
  • }
Source Code for Blink

Having a microcontroller and not controlling anything would be a bit boring but it's nice to familiarise yourself with the setup without having to get out a soldering iron. The other good thing about the Arduino from a makers perspective is that you can buy or assemble add-on boards or "shields" with features such as display, PWM motor control, data logging, sound, radio or networking. So you don't need to be an electronics wiz to put together sophisticated solutions. Because Arduino is open source there are also people who are adapting the basic board such as the Nanode project. The Makerbot also makes use of Arduino and their latest motherboard is in the form of an Arduino shield.

I do have some plans for this board that will require some electronics and a little programming, the idea is hack apart an old computer mouse and mount the sensors so I can read the angle on a simple rotary table. The angle would be displayed on an LCD display. Conveniently, there are plenty examples of code and circuits out on the internet so it should just be a case of putting a few key electronic parts together and some simple coding using existing libraries.

A big thanks to Farnell Element14 for making this project possible.

Thursday, 1 March 2012

Stirling Rally 2012

The 12th Stirling Air Engine rally will be held this year on March 25th at Kew Bridge Steam Museum. I attended last year's event and can report it was very popular, particularly the cafe.

There was a great selection of machines and engines and everyone was keen to tell you more about their creations. The Stirling Society awarded prizes for skill and innovation, last Year's Prize winners were Roy Darlington and Julian Wood shown below.
StirlingVehicles

Workshop Practice Series