BBC Micro Bit

SIMPLE ELECTRONICS ARE USED TO CREATE FUN EFFECTS THAT GET SOME BIRDS ALL A TWITTER

Using this mini computer to make this fun group of dancing birds

Birds is the project we will be creating this issue. It is built with simple electronics to create a nice effect. To build the project I have followed two separate workflows: building the birds’ cage and making the animatronics of the birds themselves, the including electronics using BBC Micro Bit.

The inside of the cage includes the laser-cut moving parts (see the article on page 66).

The cage resembles a traditional chicken cage and has a cardboard base made by painting a recycled box black. The base of the cage also contains the electronics and the moving engines. The support structure of the cage is

built with 2x3cm wooden splines joined on the top side by two M2 threaded bars to give robustness to the entire structure. Around the cage, I have fixed chicken wire that gives good visibility to the interior and a touch of realism.

All-in-one motor and servo controller

No soldering is required for the electronic assembly, which is based on the BBC Micro Bit board and all-in-one motor and servo controller by Kitronik (kitronik.co.uk). As already mentioned in the previous instalment of this column (The Shed, Issue No. 83, March/ April 2019) the board can manage up

to eight servos and four DC motors. For this project, I used all the servo controllers available.

The parts cut by laser can be cut manually without difficulty with a couple of cutters, scissors, and plywood saw, but this part of the project was made easier and took less time by using a home laser cutter instead.

The moving components are of two types — the birds, moved by five micro servos, and the tweeters, moved by continuous servos, which are very similar to a geared DC motor. The birds’ motion is simple, through a 2mm thick wire transmission. Using software delay and different starting positions the five birds all move in quite different ways.

The inspiration

This project was inspired by Rob Ives, a genial maker from the UK who creates ingenious paper mechanisms.

I had been searching for some time for a way to reproduce that ‘coo coo’ sound used in wall-mount clocks, made very popular

This project was inspired by Rob Ives, a genial maker from the UK who creates ingenious paper mechanisms

Below: The moving mechanism is of two types — birds are moved by micro servos to which a lever has been extended and connected to the bird plywood support through a transmission wire

during the ’60s and ’70s. Finally, I saw his site (robives.com/) showcasing just what I was searching for, and it was easy to build from a single sheet of paper.

First I made one of his models and it worked, then I studied a way to hack the design (released under a free Creative Commons license) and adapt it. I made a set of three different tweeters moved by the continuous servos with a rotating cam mechanism.

Designs, sketches, and the Micro Bit software (JavaScript and Makeblock) are available at the dedicated GitHub repository — https://alicemirror.github.io/birds/.

Left and right: Some phases of the building of the cage structure. The cardboard-box base will include the mechanical components and the wiring. The cover of the box, made from recycled white plastic sheet, is also the base of the birds and tweeters

Thanks to Kitronik’s all-in-one robotic board the electronic assembly does not require circuits or soldering. Here I have used a set of custom wires to connect the board to the eight servos used to animate the birds, but a set of breadboard connectors would also work. Note that I have fixed the controller board half inside the base box, while the Micro Bit side of the board is outside of the box. This solution makes it easy to keep the Micro Bit visible and means that the system can also be programmed when the cage assembly is complete

Right: After the components have been cut and the birds assembled, I add the legs made from 2mm thick metallic wire

Under each bird, I hot-glued the plywood support used by the servo to move the body Below: The tweeters are moved by a continuous rotation servo, similar to a DC geared motor, translating the rotation to a linear bidirectional movement to push and pull the paper tweeters. The moving paper part is kept in place by gluing it to the Perspex support

Top: A view of the bottom side of the cage plane with the servos and mechanisms in place Above and top right: Details of the last phase of the cage assembly Right: The finished project with the birds’ cage hung up and running