In every Chinese New Year, or happy event such as wedding, fireworks& Firecracker is always a must. Despite in order to protect the environment, we do not advocate this, but still there is a large number of people love this, especially the elderly and children. You can always see children cheered with the Firecracker, with happy face.
But Firecracker is indeed certain dangerous, especially for the children. Every year, there is a huge number of children that get hurt by playing with the firecracker. My nephew, qin, 5 years old, he likes firecrackers very much, and always scramble to fire the firecrackers during the New Year Festival. it is very dangerous, I am very worried about this.
A device that allows he to ignite the firecrackers in a safe distance would be useful, I began to plan and implement such a device by myself.
Step 1: Preparing
As a software engineer, I am not very good at the hardware. So, I brought some modules on the web to make such a device quickly.
3. A 9V Power Supply , a 3.3V power supply and Battery DC Jack
5. Some Taps and Jump Wires;
6. A Pencil and Some Heating Wire.
You may ask, how about the heating wire? This kind of heating wire need a relative high resistance to produce heat, and a high melting point, commonly, it is Fe-Cr alloy or Nichrome, you can find them in the household appliances such as hair drier.
But if you think it too trouble to open your hair drier, there is a good resource for this, that is: the metal wire that make the Window screens. It is often very slim steel wire, very suit for my application.
Step 2: Power Supply
In this step, I need to power the receiver of 315M RF Kit and the relay module (the emitter of 315M RF kit uses on-board 12V battery, do not need extra power), as the they both need 5V, so, I uses a power supply module for breadboard to convert the 9V output from the battery to 5V.
Use the jumper to connect the VCC and 5V on power supply module for breadboard, to make sure the power supply for bread board set to 5V, and connect its output(VCC& GND) to the power supply terminal of relay module and the receiver of 315M RF Kit; and then connect the 9V battery to the DC jack of breadboard power supply module.
Step 3: RF Receiver to Control the Relay States
In this steps, I connect the output of the 315M RF kit receiver to Relay module, if the receiver receives command from the emitter, it will output signal to trigger the relay, thus to ignite the firecracker.
Connect the “VT” terminal of the 315M RF Kit receiver to the “SIG” of the relay module. The logic voltage on “VT” terminal will get “HIGH” when pressing any of the button on the emitter.
Step 4: Ignite Device
In order to fire the firecracker, I used a 3V3 power supply and some Heating Wire, when the Heating Wire powered directly by the 3V3 power supply, it will get red-hot in about 2~3 second, and thus to ignite the firecracker.
Fix 2 male-to-male jump wires on the pencil as the photo with tape, and then twine the slim metal wire on the 2 terminals. This wire will get very hot and then to ignite the firecracker when they connect to power supply directly.
Connect one of jumper wires to the output of the relay module “COM”, and the other jumper wire to the “+” of 3.3V power supply; connect the “-” pole of 3v3 power supply to the “NO” terminal of relay module, that is, the circuit will normally open, but if the relay get triggered, the circuit will be connected, the slim wire will get hot to ignite the firecracker.
Step 5: Test
(This test could be dangerous, please very care about this )
Press any of the button on the RF kit, the red LED on the relay module will be off and green LED will be on.
In about 2~3 second, the slim metal wire will get very hot and get red-hot.
As it is not allowed to play with firecracker in this building, I uses some Collodion to test. It will be get burned as I press the button in 10M.
Please very notice the potential dangerous, and uninstall the battery to ensure the safety.
Step 6: Fix All the Modules
Fix all the modules in module you like, to make it easy to use . I fix them on the waste mop, this would make it more suitable for your children to ignite the firecrackers.