To summarise, we have a PICAXE directly controlling the Motor Driver board via four outputs. The PICAXE is then switching a pair of darlington transistors via another two outputs to control the LEDs. We have a switched 4.5v battery source (3x AA's) feeding the PICAXE, the LED strips and the Motor Driver. Don't be fooled by the PP3 connector in the photos, this does not connect to a 9v PP9 battery!! It connects to a AA battery box. You'll want to take your wooden spoon and remove the spoon-end with a saw, leaving you with just the handle. The stirring action pieces have a cylinder fitting on them designed to secure your spoon handle in place. It should simply just slot-in. If you find that your spoon handle is too large, sand down one end until it fits comfortably but firmly in the holder. First you'll want to fix the step motor to the motor assembly plate, this is done using the M3 screws and nuts.

To improve the effectiveness of the light effects you'll want to line the inner walls with some tin-foil. Cut a suitable length to cover the circumference of your cauldron, then put it inside and push it out into the edges.

Multibuys

For this I salvaged some cables with 2-way header connectors from a scrap PC (they are used to connect the PC front panel to the mainboard). Cut the cable to around 70mm length (connector included) then strip and tin with solder as shown in the photos provided. To create the stirring effect we are using a stepper motor, I've opted for the 28BYH-48. These motors are manufactured in large volumes so they are so cheap they're practically giving them away. They are known for missing the occasional step so not great for high precision tasks, but they are small and provide a lot of torque thanks to its 64:1 gear reduction ratio. You can read more about this motor here. The motor is commonly supplied with a ULN2003 driver, which is perfect for using with our PICAXE. The motor control is covered in more detail in the next step when we program the PICAXE. Note: When handling the dry ice always use insulated gloves, it's -80°C (-176°F) and has the potential to cause frost bite. As you'll see in one of the photos I connected my motor power in parallel with the power input on the circuit, but you could also wire the +5v at the switch side and ground it to the battery box if you prefer.

The circuits are fitted to either side of the main enclosure, there are pilot holes to enable the PCB's to be screw mounted, but I opted to use hot-melt glue to secure mine. The cables can been hidden in the battery recess below the motor assembly, I used a cable tie with a self-adhesive tie mount to keep them in place. The motor and the lights are controlled by the PICAXE microcontroller, to achieve this we use two separate programs that run as parallel tasks on the PICAXE (I believe this is only possible with the newer M2 chips).Choose one of the three stirring action pieces and slot it onto the drive plate. Line up the four pins and it should slot on securely. If the fit is too tight, use a round file to make the holes on the action plate a little larger. The motor has a 5-way connector that simply fits into the header on the driver board, the cable is a little longer than we need but not enough to cause any issues. For the lighting we are using a SMD 5050 light strip. These are really versatile light strips that are bright, offer RGB colour and can be cut to the desired length. As water is also used in this project I'd recommend getting the waterproof ones. The strips often come in kits that include a controller, you can put that to one side for another day as we don't need it, ours will be driven by a PICAXE microcontroller.

For anyone who is not familiar with the Self-Stirring Cauldron, it appeared in Harry Potter and the Philosopher's Stone. It was invented by Gaspard Shingleton and was sold in cauldron shops to assist the owner in the stirring of his or her potions. But of course, you could always use a potion stirring charm. The cauldron also has a choice of three stirring actions, making it suitable for mixing almost any potion. The complete code for the PICAXE is provided below, copy and paste this to the PICAXE Editor software and program your chip. If you are new to PICAXE I'd recommend you invest some time in familiarising yourself with it. It's really straight forward and it will revolutionise your projects, opening the door to a whole new world of possibilities. Programming them is easy and PICAXE provide comprehensive instructions and manuals, find out more here. start0: We have to start somewhere so it might just as well be where the magic truly happens, the electronics. This is divided into three main parts, the LEDs, the stepper motor and the circuit. I'll walk you through the three parts individually then we'll bring them all together at the end.

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Now here comes the fun part, the circuit. To complete this step you will undertake the following tasks: As the motor requires more current than the microcontroller is able to handle we need to connect the ULN2003 directly to our power source. You may have noticed that the motor is rated at 5-12v and our battery source is only providing 4.5v, don't worry, it's more than enough to drive the motor. Fix the motor assembly to the main enclosure, it sits on the shelf supports and superglues in place.

Note that Stirring action three consists of two pieces, the round plate and the arm. The slotted section of the arm sits in the pin located at the front of the enclosure, while the hole fits onto the round plate's pin. If you're in the UK I'd recommend RS Components, I guess that over the pond Digi-Key are pretty good too. The Cauldron is made up of four main elements, the Stirring Action (we'll be using a stepper motor for this), the Lighting (LED strip lighting) and the visual Fog Effect (here we'll be using dry ice, more on this later) ohh and of course the Cauldron (ideally a witchy type one but you can use anything you can get your hands on, I hear saucepans are all the rage amongst muggles!). For this step you just need to follow the guide in photo three, it connects four PICAXE pins to the Motor Driver header cable that you made in the last step. It uses the following pin configuration: The drive plate assembly consists of two pieces that are glued together. Make sure that the centers are aligned to allow the motor shaft to fit. You may need to use a countersinking tool to make a recess in the base of the smaller plate, this will allow the assembly to slide further down the motor shaft if necessary.Within the UK and USA the price you see is the price you pay - you won't be charged any extra fees. This Instructable uses an etched copper PCB (layouts are provided in the Ible) but feel free to use stripboard. If you've never etched your own PCB before why not give it a go, there are plenty of helpful Instructables. I'd recommend DIY Customized Circuit Board by ASCAS.