Glass Circuits

So one day I was bored and had a few things lying around:

  1.  Copper tape
  2. A pane of glass from a scanner
  3. 555 timer & passives
  4. soldering iron

There was really only one logical thing to do to assist in my procrastination, put together an astable 555 circuit on the glass!

P1010637_1Through my time learning about electronics, I have come to realise that the 555 timer circuit, astable or monostable, is one of the first circuits anyone should make.

However for those who don’t know about it here is a short explanation of the astable circuit.555astable

The 555 timer IC is a a circuit of over 40 components, including 25 transistors and 15 resistors, all printed on a silicone chip.

The circuit works by flipping the voltage states of different pins on the IC. Initially pin 7 is high and so the current flows though R1 & R2 to charge the capacitor. Pin 6 detects the high voltage build up on the capacitor and toggles pin 7 to be pulled low, this causes the capacitor to discharge through R2. While the capacitor is discharging, pin 3 is pulled low, turning off the output, however when pin 2 detects the low voltage on the capacitor, pin 7 is pulled high again, allowing the current to flow through R1 & R2 again.

555 Astable GIF

And ofcourse there is some maths to work out the length of each high and low pulse for given component values, and thus the frequency as well.

f = 1 / ( ln(2) * C * ( R1 + 2R2 ) )

High = ln(2) * C * ( R1 + R2 )

Low = ln(2) * C * R2

And so with values of 1000Ω for R1 and 10KΩ for R2, and 100μF for C1, we get a high pulse of 0.76 seconds, and a low pulse of 0.69 seconds and a frequency of 0.69Hz (687 mHz).

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testing timer

Having a go at Book Binding

For some time I have wanted to have a go at book binding. It seems like a great thing to do as a gift for a loved one, but maybe that’s just me. Well I decided to make my girlfriend a photo album and sketch book as a Christmas present. Hence why this is being published after Christmas to avoid her surprise being ruined. On the next occasion that I decide to make a book I would choose paper with a lower gsm that I have done for these. I selected 300 gsm, which is great for the photo album, however for the book it is a little too thick to easily flick the pages.

Anyway, to the book binding process. After having folded 20 sheets of paper I clamped them together in-between two other books (sheets of wood are better) and then coated the folded edges with Copydex, a latex based contact adhesive, and a cut of cloth placed over it. By doing this the Copydex soaks into the cloth and the paper to make a reasonably strong joint.

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Now that the pages have been bound, its time to make the cover. Using 5mm rigid foam and sticky back cloth, I cut out the front, back and the spine and laid the parts out on the cloth. When doing this make sure to leave a large border of cloth which is used in the next step to cover the edges.

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Alas I forgot to take enough photos but the next step is to fold the edges of the cloth up and over to cover the edges of the board. this can be a little tricky because of the sticky-ness but it looks good if you persevere.

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In order to securely join the pages and the cover, we have to use a joining page which gets glued on the front and back cover, and the front and back of the stack of pages. Finally we are starting to look a bit more professional and are ready to glue in the pages.

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Make sure to use a nice big weight when gluing in the pages just to make sure everything is nice and flat!

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No photo’s of the finished book. Sad times.

Hameg 203-4

As usual you can find some great bargains on eBay!

A few weeks ago I brought my first oscilloscope, a Hameg HM203-4, on eBay for £14.51, quite a deal I think. It was sold as “For parts or not working” as the seller didn’t know anything about oscilloscopes  or how to use them.

The Hameg HM203-4

The Hameg HM203-4

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I do love that there is a warning about the X Ray dosage!

Although it was sold on eBay as good condition, one of the buttons was missing. Fortunately I was able to see it inside the casing and so wasn’t too worried.

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So its time to crack it open and see what’s inside . . . Just two screws on the back and the whole metal chassis slides off.

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just two screws on the back

With the metal chassis removed we get our first glimpse into the home of the magic smoke. Just as I had hoped the missing switch was just a case of the shaft having popped out of the holder, I wonder what happened. . .

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A nice easy fix =]

So now that is fixes, here are some specs. Its a dual channel scope with a bandwidth of 20 MHz its not the fastest beast out there but then its not the slowest either, backed up by a max input sensitivity of 2mV/cm. One feature I’m interested to try and think might be pretty good for me as a student is the component tester. to make matters even better its apparently recommended for the training of engineers, perfect.

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What a pretty board

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Poles Poles Poles, and a little bodge :-)

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I was amazed to find capacitors without venting on the top!

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At least the CRT was made in 1983.

In the Aftermath of the Mini Maker Faire

The dust is settling now after the hordes of people who wandered through the halls of the Elephant & Castle Mini Maker Faire.

Within the halls of the London College of Communication, makers were separated by categories into different studios. We had lots to look at and admire, however Raspberry Pi’s and 3D printers, not surprisingly took centre stage.

I don’t intend to talk about everything that happened, just a few things that really made an impression on me.

One 3D printer that caused me to take a second glance, and a third, and a fourth, and a chat with the creator, was the 3DR.
The 3DR is an inverted delta-bot style 3D printer that is constructed mainly out of 3D printed parts. Because of the simple design it seems to me that it must be must easier to set-up initially as the only areas you need to focus on are how tight the strings/cam belt are, and the position of the 3 arms, of course that is only the case if the rod guides are all the same height and parallel to each other.

A 3D printing company caught my eye as we wandered around because of their impressive printed objects and nicely build RepRap printers. Active 3D is based in Tunbridge Wells and aim to help introduce schools in the area to the opportunities that are available in 3D Printing. They offer workshops and monthly meetups which aim:

  • To train people in how to use 3D printers.
  • To train people how to maintain a 3D printer.
  • To provide an easy to use instruction manual.

And finally, catering to the more artistic of us, and the thirsty, the Tropism Well could be found in one of the main halls.
The Tropism Well is a drinking fountain with a difference. With a base made up of a 14 litre tank, which can be filled with any beverage, the Well automatically detects the presence  of a person and elegantly bow’s its neck, presenting to the honoured person a gift of a perfectly poured serving or a drink, before bringing its neck back up straight as if to observe you enjoying its gift.

Elephant & Castle Mini Maker Faire

 

Elephant & Castle Mini Maker Faire

So the three of us are off to The Elephant & Castle Mini Maker Faire on Saturday.
Maker Faire’s were created by Make Magazine in the USA, they are now events that happen all over the world.

Currently in the UK we have 6 Mini Maker Faire’s in; Brighton, London, Nottingham, Manchester, Dublin and Edinburgh. There is also a “featured” Maker Faire in Newcastle. Find your nearest Maker Faire here.

On the agenda for the Elephant & Castle Mini Maker Faire in London are loads of workshops including learning to solder (Through Hole and Surface mount),  creating a mini synth and 3D modelling in Blender. See the full list here.

We are really looking forward to the day and will update everyone with what we see and do! =]

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Twitter LED

For future projects and general usefulness I have decided to try to learn a new programming language. I have decided to try python for two good reasons, because it is a good language to program projects with the Raspberry Pi and because a large chunk of my course next year is programming simulations in python.

For my first program I’m going to do a twitter feed controlled LED, I also plan to incorporate twitter into a later project so this is a good starting point.

Ingredients list: A Raspberry Pi, an LED, a 220 Ohm resistor, Internet access and a Twitter account.

First take an LED and a 220 Ohm resistor and connect the resistor to the cathode of the LED. Then connect the anode of the LED to pin 7 of the GPIO pins on the Raspberry Pi and the resistor to pin 25 using two female to female jumper wires. A GPIO pin layout diagram can be found here. Once you are sure this is done correctly, a mistake could damage the Pi, boot up your Raspberry Pi ( I am using Raspbian Wheezy). This is all the hardware setup.

prLED

Now to install the appropriate libraries type this into the command line:

wget https://raw.github.com/Rob-Bishop/RaspberryPiRecipes/master/InstallTweetLEDLibraries.sh

Now run the installer by typing sudo: sh InstallTweetLEDLibraries.sh

Okay you know have the appropriate library the next step is to create the file. I’m using nano, to make he file type this command:

nano TweetLED.py

In the editor you just opened type the following code, quick tip press CTRL X to save and exit the editor. Note, I am going to put ; at the end of each line to make the program clearer do not put these into your program.

import urllib ;

import simplejson ;

import time ;

import RPi.GPIO as GPIO ;

;

GPIO.cleanup() ;

GPIO.setmode(GPIO.BOARD) ;

GPIO.setup(7,GPIO.OUT) ;

;

def latest_tweet(twitter_handle): ;

twitter_results = urllib.urlopen(‘http://’+’search.twitter.com/search.json?q=’+twitter_handle) ;

result_list = simplejson.loads(twitter_results.read()) ;

return result_list['results'][0]['text'] ;

;

count = 1 ;

;

while count > 0: ;

tweet=latest_tweet(‘@JamesLeftley’) ;

;

if ‘on’ in tweet: ;

print tweet,’ – LED ON’,’\n’ ;

GPIO.output(7,GPIO.HIGH) ;

;

if ‘off’ in tweet: ;

print tweet,’ – LED OFF’,’\n’ ;

GPIO.output(7,GPIO.LOW) ;

;

if ‘stop’ in tweet: ;

print tweet,’ – Stopped’,’\n’ ;

GPIO.output(7,GPIO.LOW) ;

count = 0 ;

;

time.sleep(2) ;

Now save and exit using CTRL X and you should be taken back to the command line. To run the program type:

sudo python TweetLED.py

To stop the program tweet stop, to turn the LED on tweet on and to turn the LED off tweet off. The tweets can say anything as long as they include the twitter handle, in this case @JamesLeftley, and the command. All the commands are case sensitive.

To personalise the program change the twitter handle, add more outputs and change the commands.

London Arduino

Tonight was my first time along at the London Arduino Meet Up.
The London Arduino Group is of a similar idea to the Raspberry Pi Jam events that I’ve been to
before. It is a group of people who want to share knowledge about the Arduino platform and start to
innovate across other platforms.

This month we had presentations including hobby electronics, internet controlled LED’s and 3D
printing.

Using an Ethernet shield, Christian, put together a set up where he was able to control the status
of an LED in his web browser. This was done on a local network (sorry guys who wanted to take
control of his little light) where he showed two methods of flicking the switch.
The first method he showed off was to use the arduino as a web server and construct the html on it
as well. Then it was a simple matter of connecting to the IP address that was defined on the
arduino and hey-presto it worked.
The second method that he demonstrated was a little more complicated involving node.JS, sockets and other technical jargon that I didn’t catch.

On a similar vein we had Liam demonstrating the use of a TP-Link Wireless N Nano Router (TL-WR702N) to connect an arduino to the internet. He argued that the use of WiFi shields is overly complicated compared to Ethernet shields, as well as being a lot more expensive  So if you are willing to have a slightly bigger package then you can connect the Ethernet shield to the nano router and leave that to sort out the complicated subtleties of wireless connections, allowing you to get on with innovating your wireless solution. Another thought is that a nano router is much more versatile than a WiFi shield because it can be plugged into a computer, games console, Raspberry Pi, or any other device that has an Ethernet socket.

In the realm of Hobby Electronics we had Danny, who was plugging his first ever kit robot. Orionrobots.co.uk is his creation and is where he is selling his first his own starter kit robot. In this kit you will find everything that you need to to construct a small chassis with 4 wheels controlled in pairs (left and right) by a L298n dual H-Bridge controller board which is interfaced to an Arduino Uno R3 (provided in the kit). With a easy fit design, you only need a screwdriver to put this kit together making it perfect for anyone who is; unsure with tools, in need for a robot chassis quickly, or just lazy.

The final talk of the evening was from Mark, on behalf of another London Tech Meet-up group, Future Manufacturing, who have a keen interest in 3D printing. They are really keen to see cross collaboration between our two groups on various projects including potentially the Luma Module Interactive Spaceship. The Luma Module is a KickStarter project where they want to build a spaceship that lights up when people interacts with it. This spaceship will then be shipped (no it won’t fly itself) to Nevada for the Burning Man art Festival at the end of August 2013.

Troubleshooting

So far I have built the cloud chamber and have moved on to testing. It came as no surprise that it didn’t work first time and the problem is obvious, cooling. The heat sink I am using is not up to the job of cooling the Peltier coolers, again no surprise as it is about 6 years old.

I attempted to solve this with more fans.

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The heat sink still reaches about 40 degrees which is about 10 degrees to much, the next step will be to clean the 6 years worth of dust from it and if that fails a new(er) heat sink may be in order.

Progress Update

Previous Post

So finally enough of my parts arrived to start building :)

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So far I have:

An old cpu fan, a 500ml pot, thermal paste, a TEC1-12710 cooler, a TEC1-12709 cooler, an old ATX power supply (450W), glue, a knife, some metal, some uranium glass, a torch, scissors, nuts and bolts.

If you are interested in building this project yourself I would recommend waiting until I have it working properly. :)

This first part is the same as the the first part of the Instructables link in my first post and has been proven to work.

To start off I measured out a hole for the 12709 in the base of the pot, the coolers are 4cm by 4cm, and put it to one side. Next I cleaned and put thermal paste on the cpu fans heat sink.

Cpu heatsink

The paste should form a complete layer as thin as possible on the heat sink. The cooling is by far the most important and difficult part of this project and is very prone to going wrong. Place the 12710 cooler on top of the thermal paste, with the heat sink orientated as in the picture and the 12710 cooler on top with the wires towards you the red wire should be on the right.

A quick check is now needed, make sure the PSU is unplugged. On the main power connector connect the green cable to one of many black cables, this is the PS on connection and will allow the power supply to fun whilst not connected to a PC.  Plug the CPU red cable to a yellow cable, all yellow cables on all of the plugs are 12V, and connect the black to a black. The same goes for the 12710 cooler, red to yellow, black to black. A useful page http://www.smpspowersupply.com/connectors-pinouts.html

Pin layout

This next part must be done quickly, place a finger on top of the 12710 cooler and plug the power supply in. Make sure air can flow through the fan and turn it on.

If the fan doesn’t spin turn it off and check your wiring, if it still fails to spin unplug the 12710 cooler and use a multimeter to check if there is a voltage being produced by the power supply, if there isn’t make sure the green and black are connected. If there is still nothing then your PSU may be broken check the fuse first though.

If the 12710 cooler gets hot switch it off quick, it is upside down. If it gets noticeably cold then it is set up correctly, turn it off.

Place thermal paste on top of the 12710 cooler same as before as thinly as possible and place the 12709 on top. Both should be orientated the same way, wire colours on the same sides. Now for a check, the set up is the same as before apart from the red wire from the 12709 goes to a red wire in the socket (5V). The cooler should get very cold, around -25 degrees Celsius or better.

Up to this point is the basis of the cloud chamber, from now on this is all experimental and has a high chance of not working properly. Again it is advisable to wait until I have it working before making it yourself.

At this point I went back to my pot, on all the cloud chambers I have seen the dry ice or other coolant is connected to the plastic. This didn’t seem very efficient so I cut a hole in the plastic and mounted it on the cooler.

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I used the glue to keep it sealed.

Following this I made sure pressure was applied and the whole thing couldn’t twist by using some nuts and bolts and I fixed a plate, using thermal paste, to the top cooler to give it a larger surface area.

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I switched it all on for a test and found that water in the atmosphere condensed and froze on the metal plate, I took it as a successful test :P

Until my Isopropyl alcohol and thermometer arrives I can’t test it any further.