Wireless Dark Magic Candle

A dark magic candle that is lit wirelessly by muscle impulses. It is obvious that for someone who does not know that it works through radiofrequency, it is frightening, right? So in this tutorial we have the following goals, and your creativity is important to make improvements:

1) Decorate a candle in order to look frightening, and make a hole inside to insert the components.

2) Create the module that will be connected to the arm with the arduino, the heart rate sensor and the radiofrequency.

3) Create the system inside the candle which will have two LEDs, one normal and one RGB, the Arduino and the radio frequency to connect with the arm.

4) Write the code to make this all work!

HARDWARE

1. Arduino Nano
2. Arduino Uno
3. AD8232 Heart Monitor
4. ECG Electrode sensors
5. Radio frequency module nrf24l01 (x2)
6. Red LED
7. RGB LED
8. 240Ω resistances (x4)
9. Wires
10. 9V Switched Batteries (x2)

TOOLS AND MATERIALS

• A big candle
• A cutter
• Soldering iron and tin
• Acrilic paint
• A lighter
• Elastic mesh
• Two 10x12cm boxes or 3D filament

SOFTWARE

• Arduino IDE

In order to decorate our dark occult candle, we will only need a candle of any color, black and red acrylic paint, a cutter and a lighter. The steps are the following:

• First of all, we are going to burn the top edges of the candle so that it looks like it has been used and is more like a real candle.
• Then, with the cutter, we empty the inside of the candle to be able to insert the electronic components inside, and with the same cutter, we draw a satanic star by way of sharp cuts.
• Once the previous steps are done, we paint the candle black, and fill in the satanic star-shaped indentations with red acrylic paint to make it look like blood.

And we would already have the candle decorated for Halloween, that's how easy this procedure would be.

The receiving system consists of two parts. The first part is responsible for receiving the data that is sent by the sender. The second part deals with the LED lighting, which tries to emulate a flame. The connection of the radiofrequency receiver must be the same both in the transmitter and in the receiver, as indicated in the following diagram. In the case of LEDs, it is necessary that the connection be in analog ports since the program will modify the intensity and color of these. Finally, to finish the electronic part of the assembly, it will be necessary to connect the battery with a built-in switch.

All this system will be assembled in a box that will be attached to the sail in order to hide the system. The 3D file is below.

Assembly summary:

• Solder the radiofrequency device to the arduino.
• Solder the leds to two resistors and two analog inputs of the arduino.
• Protect the assembly with heat shrinkable plastic.
• Place the components in the box so that the switch matches the hole.
• Glue the box to the candle.

The code of the receiver activates or deactivates the LEDs depending on the message received by the receiver (1 or 0). It consists of two parts:

• Part 1-reception of information: party receiving information.
• Part 2-activating part: Contains the conditional structures that activate the control of the LEDs. The RGB LED has a variation between yellow and orange, the red LED varies its intensity.

To make the candle light with muscle impulses, we need three key components to form the emitter of the muscle impulses: an Arduino Uno board, a heart sensor and a radio frequency module.

For the assembly of the electronic part of the emitter, the different components must be connected as shown in the diagram below.

The system collects information from muscle stimuli. The Arduino board through conditional code sends 1, in case of wanting to light the candle and 0 in case of wanting to turn it off.

A battery with built-in switch will be added to this entire system.

The entire electronic set will be assembled in a box. The 3D file is below.

This box will be attached to a mesh in which the cables of the cardiac sensor will be found. these will go under the mesh and will be connected to the system through a hole located both in the fabric and in the box.

Assembly summary:

• Solder the cardiac device to the arduino board.
• Solder the radiofrequency device to the arduino.
• Connect the battery to the plate.
• Insert the system in the box so that the switch coincides with the hole and the hole with the jack input of the sensor.
• Glue the box to an elastic stocking previously cut to the size of your arm.
• Connect the electrocardiogram cables to the sensor through the hole in the fabric and box, leaving them below the elastic stocking.

This code consists of three main parts:

• Part 1-Start of the connection: The radiofrequency connection is initialized by establishing both the pins and the communication channel.
• Part 2-Conditions: The sensors are read by performing the conditional operations that determine the message to be sent (1 or 0). The operation saves the data at different times to check if there are peak values, thus avoiding having to recalibrate the sensor every time the user changes.
• Part 3-Sending: The information is sent (1 or 0) depending on whether the previous conditional structures are met. Conditional structures also take into account the switch-like structure.

At this point, the candle should be ready to use. The emitter will be placed on the arm so that the box with the components is above the elbow but the electrodes are on the forearm.

• Step 1: Turn on the switch of the batteries of the candle and the emitter of the arm. Wait two minutes for the connection to be established between both devices (this time should only be waited on the first use of each time)
• Step 2: With the stocking folded up to the box, place it on your arm, leaving the box above your elbow.
• Step 3: Place the electrodes as indicated in the following illustration.
• Step 4: Cover the cables with the elastic mesh, in order to hide them.
• Step 5: To turn the candle on or off, activate your arm muscles. It is recommended to add a theatrical touch to the gesture such as the opening of the hand, in this way it will seem that the candle is activated by magic!

This project has been developed as a work for the subject of uses and specific terminology in English taught at the Elisava University of Engineering and Design. It is a project that, despite the complexity of wireless communication, is suitable for anyone with basic knowledge of Arduino to develop it successfully. The interpretation and reading of the sensor is complex but it is solved with mathematical operations and a simple program. Special care must be taken when welding since the plates, especially the heart sensor, are very delicate. We recommend using heat shrinkable plastic to protect the joints and plates. It is very important that at the time of assembly, an independent test of communication, sensor operation and LEDs is carried out, using simple programs.

The following test codes are for testing each of the components. In the case of the sender and the receiver, they must be uploaded on both devices, the receiver must receive the word ''hello world'', which will be displayed on the screen of the computer to which the board is connected.