mechtopia

Austerity Christmas tip #232: DIY Chocolate advent calendar

Chocolate advent calendars are often pricey, and the chocolates inside disappointing. Why not make your own advent calendar by cutting windows in the top of a chocolate box.

Posted at 05:11PM Dec 20, 2011 by ohp in Projects  |  Comments[0]

Hivegraph: collaborative infographics

www.hivegraph.com

In the upcoming weeks I will be blogging new charts created using hivegraph. Hivegraph is a new site that I've created. The site has a single data set that can be used to generate a wide variety of graphs. Current functionality is based around comparing items, and users can collectively add data, and create new charts. As new graphs and charts are created, I will also extend the functionality, and let users do more.

Posted at 07:52PM Oct 17, 2011 by ohp in Projects  |  Comments[0]

Refractive index bubble display prototype

Here's something I've been playing with. The idea is that you have a block of acrylic (or other transparent material) and within the acrylic there is a chamber milled out. When the chamber is filled with an oil with a matching refractive index, the outline of the chamber becomes indistinct. You can "turn on" the display element by draining the oil from the chamber, at which point a bubble appears within the acrylic.

Element "off" (filled with oil)	Element "on" (oil removed)

It was influenced by an exhibit I remember from the science museum in London, which had a perspex block containing a number of different fluids with different refractive indices.

I demonstrated this basic prototype to a gathering of Ipswich science in the pub on Tuesday 19th July, 2011, and we discussed various ways of improving the design.

There are still lots of issues to overcome:

• It's messy: oil gets everywhere
• Pumping oil to multiple chambers requires multiple drivers, which makes it expensive and unreliable.
• It'll be hard to ensure that the drivers don't underfill or overfill the oil in the chambers.
• Long term, the properties of the oil and acrylic are likely to change, especially in the harsh lighting conditions that show up the effect.
• How do you account for thermal expansion?

Currently I have a strategy for increasing the contrast between the two states: You can easily see the machining marks inside the perspex in my prototype, and I'll be making the main chamber rounder (rounded chambers show the effect much more), and the feed tubes squarer in order to enhance this effect, and using heat to remove the tooling marks. I'll then look at glueing the two perspex halves together, so that the block becomes one sealed unit.

I'm not sure if this is patentable, I haven't found any other patents in this area, and much googling has thrown up nothing. I did consider trying to patent it, but I'm releasing this idea into the public domain, as I didn't expend much research money coming up with it, and I don't think it's a practical display technology that's likely to make much money, but may be a fun idea to exploit for people who perhaps want to build it into art installations and one off pieces.

I eventually want to build a digital clock that uses this as a display, with different segments being driven in this manner. You could also make simpler designs, perhaps mill a single chamber into lettering, creating a sign that you could turn on and off. OPEN/CLOSED maybe? This car park is full? There are also a number of options for drivers, from solenoids to servos.

Posted at 12:00AM Jul 25, 2011 by ohp in Projects  |  Comments[0]

Q: what is the storage capacity of 78 floppy disks? A: 27 litres.

I've been thinking about using discarded objects to make useful items. This is a box made from 78 floppy disks. It is made from floppy disks and hot glue only.

Posted at 05:00PM Jul 12, 2011 by ohp in Projects  |  Comments[0]

Tracking passengers on the UK rail network

This is a mashup that takes tweets from rail passengers, and plots them on a map. Currently the system uses a simple sequence of keyword filters to decide what the tweet is about, and to categorise the tweet.

Even in the short period of operation, there appears to have been a spate of animals on the line, and it's interesting to see lines of tweets that follow rail routes when there is a delay on the whole route.

Upcoming releases should include:

1. Bayesian filtering rather than keyword filtering
2. Overlay National rail tweets
3. Logical, rather than physical map

To visit the site, click on http://www.ukrailtweetmap.co.uk

Posted at 10:12AM Jan 20, 2011 by ohp in Projects  |  Comments[0]

What is this?

To find out, come to the time show in Ipswich, this weekend:

Posted at 12:41PM Oct 02, 2010 by ohp in Projects  |  Comments[0]

The dowse-o-matic 1000

Recent visitors to my blog may have read the post about the busk-o-matic 3000. buoyed with enthusiasm for constructing computer controlled mechanical devices, I have been pondering the creation of a dowsing device.

The aim is to allow people to test their dowsing skill in an automated fashion. My preliminary thoughts are to have a pair of reservoirs linked by a pair of tubes. A computer will randomly select one of of two solenoids that will allow water to flow from the upper to lower reservoir via one of two paths, and the dowser will press a button to indicate which of the two tubes contain the flowing water.

This process will be repeated until a statistically significant number of tests have been performed.

I don't for one moment think that this apparatus will fulfill every dowsers requirements for a test... I see it more as a fun device to make scientific testing more accesible to the masses.

So.... what do you think? Do you have any suggestions?

Posted at 11:40AM Nov 02, 2009 by ohp in Projects  |  Comments[0]

The Busk-o-matic 3000

Ever since attending my first karaoke night, I've wondered if I can harness the power of the wailing and catterwalling masses for the good of mankind.

So I created a device, which I have called the busk-o-matic 3000

Here's how you use it:

• Each singer is given an RFID chip that uniquely identifies tham as a singer.
• The singer places an RFID chip on the back of the unit at the beginning of the song.
• As the song progresses, the audience puts money in one of two slots, depending on their positive, or negative reaction to the act.
• A running balance of positive and negative contributions is indicated by the arrow.
• If the arrow should move into the red zone before the end of the song, it will be ended prematurely.
• At the end of the night, prizes can be awarded to the best singer, the singer that raised the most money etc..

Here's how it works:

Coin counting is done by a pair of Mars Electronics Cashflow 126 coin mechanisms. These are nice mechs in that they have a nice simple parallel interface mechanism, which is pretty cheap and easy to interface with. I've used a phidgets USB 16/16/0 interface board to interface with the computer.

The RFID reader is a phidgets USB RFID board, which reads the unique 125khz em4102 tags

The arrow is moved by a standard rc servo, via a usb phidgets servo controller.

The brains of the operation is a java program that maintains an internal database of all of the deposits made. This can be queried for winner reports.

The unit has been tested in a real environment. In an hour and a half, 11 singers raised 67 pounds for charity.

First Test Run

Here are some charts generated by the Busk-o-matic's internal database after the first test run.

Improvements to be made:

• Improve coin validation. About 30% of the coins were rejected. Some coin path modifications would address this.
• An audible and alarm when the singer has reached the low threshold
• Make better use of the coin sorting mechanism offered by the mechs.
• The unit could be made more visible in dark lighting enviroments
• Nicer looking case
• Enclosed arrow, so that people don't try to break it off!
• An embedded motherboard. I have plenty of spare ITX boards on which I can run Linux

Watch this space... coming soon, the busk-o-matic 4000!

Posted at 11:57PM Oct 06, 2009 by ohp in Projects  |  Comments[0]