Rachel’s original design of the “Pig in a Bucket” is shown in the photo below, bottom centre. She wanted her pig to make sounds when you squeezed its nose. We have also added sensors to the ears!

Group photo, showing Rachel’s “Pig in a Bucket” at the front.

This is still a work in progress, and although much of the hardware has been constructed, the sensors for the nose and ears have yet to be built. Here is what we have so far.

There’s a hole in my bucket ..

We started with a plain galvanised 15l steel bucket, and then cut the bottom out of the bucket with a jigsaw to provide access to the electronics (when they are fitted). The hole had quite a rough edge after using the jigsaw, so this was flattened down with a planishing hammer and dolly!

Galvanised steel bucket with the bottom cut out.

A small hole was also drilled in the side of the bucket for fitting the on/off/volume switch. The electronics are mounted on a wooden panel that fits into the bucket near the bottom, but leaving enough room for the electronics. The photo that follows shows some of the electronics mounted onto the board:

Amp and speaker mounted on base board – the Arduino was removed for this picture.

The board was glued into place in the bucket, so that it does not fall out:

Base board glued into place near the bottom of the bucket

Rear view of bucket showing the base board with the electronics mounted. You can see the on/off/volume switch at the side of the bucket. The sound is produced by an Adafruit WaveShield attached to an Arduino Uno. The sound is fed through a 3.5W mono Kemo amplifier and into a 5W Visaton full range speaker. There is a small amount of buzz which I haven’t managed to remove, but it is not noticeable when the sound is playing. The whole thing is powered by a 1000mAh Turnigy Li-Po RC battery, as they are light and powerful.

Bottom view – Electronics mounted onto base board and glued into the bucket

The bucket still needs to be decorated (as per Rachel’s design), the pig fitting and the sensors fitting to the pig. We’re hoping to complete this part by next week ready for the next workshop at MERL.

Below – we are attaching the new nose (containing an off the shelf pressure sensor) and the ears (which each contain a pressure sensor constructed form resistive plastic). The pressure sensor in the nose is situated between the cream coloured foam and the pink foam which forms the end of the nose (which Kate made independently, and managed to get the dimensions spot on!). It was intended as a ‘push’ sensor, so pushing on the end of the nose would trigger the sound, but it also appears to work well when squeezed, which is an added bonus.

Adding the new nose and ears to the pig

The ears were more difficult to construct. We wanted the whole area of the ear to work as a sensor, rather than an isolated area, which would be the case if we used a small off the shelf pressure sensor. So we used conductive (copper taffeta) fabric with resistive plastic (Velostat) sandwiched in between. The resistive plastic becomes more conductive the harder you squeeze it, so it works like a simple variable resistor.

Constructing the ears from resistive plastic and conductive fabric

One downside to the construction of the ears was that they have to be kept flat. Bending them would lose the resistivity. We did (obviously) try to create curved ears, but they were very inconsistent in operation and unreliable. Hence we stuck with flat ears and made sure they were attached to the pig flat! The wires were attached (using ordinary wire) to the ears by sewing them with conductive thread to the tabs at the bottom (see image below), and then gluing in place:

Squeeze sensor ears for the pig in a bucket

There was also a slight bug in the software when we initially tested it out, but it was easy to solve, and the finished item is below. It’s beautifully colourful!

Rachel’s ‘Pig-in-a-bucket’

Development of the mooing boot.

In the image below, Sian is holding the boot that she developed at the workshop sessions that we held at MERL. She covered the boot with faux cow hide and wanted it to moo when touched.

Sian holding the wellington boot covered in faux cow hide that she designed. This is the original boot which was used as the basis for the mooing welly.

To produce the mooing sound, we used an Arduino UNO together with a wave shield, a 3.5W mono amp and a small speaker:

Arduino UNO with waveshield and amplifier

To trigger the sounds with the Arduino, two contact microphones, a tilt switch and a pressure sensor were used. The two contact microphones were stuck to cardboard bases (about 10cm square), and the bases were then glued to each side of the boot – these formed the strokable areas:

Contact mics before attaching to cardboard bases.

Initially, we tried to construct a simple squeeze sensor using resistive plastic (Velostat) and copper fabric. However, although it worked very well when constructed as a flat sensor, the curved version that was attached to the boot was very tempremental! Subsequently, we opted for a pressure switch which works very well:

Pressure switch using to trigger a sound when the toe area of the boot is squeezed.

The speaker was attached to a wooden base which fitted inside the opening of the boot and secured from slipping with a thin aluminium band screw into the boot. This was later covered with fur to match the boot. The image below shows the fur being attached with contact adhesive:

Faux cow hide being attached to the speaker base.

The Arduino sketch that triggers the sounds was written so that when the sides of the boot were stroked, the toe squeezed or the boot tilted forward, the sound would play. The sound will continue to play as long as the boot is stroked or the toe squeezed and will stop approximately 2 seconds afterwards. Email me if you would like me to send you the Arduino sketch.

Here are some images of the final boot – we will upload some video when it is tested out:

The mooing boot

Below is a picture of Claudia holding the boot after attaching the faux hide – she did the nice needlework!

Claudia holding the mooing boot

The littleBits go LARGE project now has its own page on this site: littleBits go LARGE

As our project “Making Electronics Accessible to People with Learning Disabilities” satisfied the criteria for Design for All (http://designforall.org/) we can now use the logo in association with this part of the project:

Design for All

Here is the full size potato battery. It is made from a plank of oak, with a plate of zinc and a plate of copper screwed to it. The metal plates have dimensions 80mm x 1000mm, and were chosen so that they would fit on a 1m plank. It hasn’t yet been tested, but we might schedule this for the workshop on Thursday … 🙂

Full size Potato Battery

The next stage is to attach the wires that will connect the potato battery to the microcontroller. We’ll use simple screw terminals, and screw the wires to the plates.

The ‘smell box’ has finally arrived! It is based upon the same container as the prototype (so currently a bit large), and uses the same low power PC blower to move the air around. A 4N35 opto-isolator is used to separate the littleBits circuit from the circuit that powers the fan (which is controlled by a BC547), and the whole thing is powered by a 11.1V LIPO RC battery:

Similar to the Sound Box (see below) the Smell Box has littleBits circuitry integrated, and can be activated by any of the littleBits triggers:

The ‘smell’ itself is placed inside a small box embedded in the lid of the Smell Box. There are some ventilation holes drilled in the smell container (the off-white thing in the lid) and also a number of vents scattered around the box itself. It was tested with a piece of goat cheese:

To contain the smell of the cheese, the lid was pressed onto the smell container (which is almost air tight). However, the circulation was quite poor (despite the numerous ventilation holes), and so was tried again with the lid partially off:

This was better, and you could get a good sense of the cheese smell wafting from the box. But the design could be improved significantly in a number of ways:

1. A much more powerful fan is required to get air circulating properly. A PC case blower seems to be a bit too weak for this purpose.
2. The smell container needs to have some form of mechanism to contain the smell when the device is inactive. This could consist of a simple set of spring loaded flaps which isolate the smell, and which open only when the device is triggered and the fan starts.
3. More ventilation holes in the main box, so that a good air volume is produced. Currently the air volume from the device is quite low, and so the smell is rather ‘subtle’.
4. The air vent from which the smell emanates is currently to low down, and would ideally be placed on or near the top of the box.

We will trial this next week (18 Nov 2013) and see what happens with our target group. A report of how well it worked will be posted here soon.

In the meantime, we’ll be developing version 2 of the smell box, and include the improvements. Rather than hack boxes to pieces to make the new version, it would be a good idea to 3D print the next one. We’ll post the design on here when it is ready.

The Sound Box has had another update, and now includes an external speaker socket. this means that it can be plugged into an external amplifier/speaker or some other output device that can handle the analog signal. The image below shows the new jack socket with a device already connected via a jackplug:

Sound Box with new external plug socket

In the next image a surface transducer (a surface speaker) is plugged into the Sound Box. The transducer itself is attached to a 1.2mm zinc plate with a strip of BlueTack. The transducer makes the zinc plate vibrate to produce sound.

Transducer attached to a zinc plate with bluetack

The final image is a close-up of the transducer. You can buy these for around £5.00 each (or less) from many outlets on the web.

Transducer

The next experiment will be to connect the Sound Box to an external amplifier, and from this to a much more powerful speaker. The speaker will be attached to a metal plate and we will look at how the sound waves propagate on the surface of the plate to produce patterns (visible using fine sand or powder).

For one of the forthcoming workshop at MERL, we might explore how potatoes can produce energy using a setup similar to this, and demonstrate that you can do more with a potato than boil it, mash it or make chips (french fries, if you are not from UK). The images below show the simple battery setup using a zinc plate and a copper plate with a small gap between them.

Zinc and copper plates

A potato (or two in this case for a larger current) is placed across the plates:

Potatoes placed across the two plates

The current measured across the plates was about 160uA:

Measuring the current generated by the potato battery

The next stage of development will be to drive a set of LEDs to indicate the current generated.