Introduction: LED Fireworks

About: I'm a mechanical engineer, and I like computer programming, mechanics, electronics and specially the robotics.
Nowadays technology changed everything. Things that have been made many years ago are now appearing in a new form with new and modern parts.
So I decided to simulate fireworks with LEDs and made a machine that makes LED fireworks.
It works simple, there are a lot of LEDs that everyone is connected to a capacitor with a resistor, the machine charges the capacitors and a timer drives a motor that strews them around.

Step 1: Things You Need

To make your own LED fireworks machine you need the following things and tools:
  • Some colorful LEDs
  • Some 1K resistors
  • Some 470uF capacitors (or higher)
  • Two plastic disks
  • Some screws with bolts
  • A long narrow plastic strip
  • 1x 1N4007 Diode
  • 1x 1N4148 Diode
  • 2x 100nF ceramic capacitor
  • 1x TIP122 transistor
  • 1x 50K potentiometer
  • 1x 33K resistor
  • 1x 100K resistor
  • 1x 100uF electrolyte capacitor
  • 1x 3.3uF electrolyte capacitor
  • 1x BC547 transistor
  • 1x 555 IC + socket
  • 1x Simple push button
  • 1x Small motor
  • 1x 9V battery + connector
  • Some wire
  • Foil
  • Drill
  • Screw drivers
  • Soldering iron
  • Soldering oil
  • Soldering wire
  • Glue
  • Pliers
  • Wire cutter
  • A bubble bag
  • Things to make a PCB (if you want to have a circuit board)

Step 2: LEDs

Just solder each LED to a 470uF capacitor with a 1K resistor among them.

Step 3: The Circuit

There are two timers, one for a short delay before starting the motor and strewing LEDs (about 0.5-3.5 seconds) and one for stopping the motor after a while (about 5 seconds).
The first delay can be changed with a 50K potentiometer.
You can make this circuit by soldering components together (step 4) or by making a PCB (step 5).

Step 4: Soldering Components Together

The best way to make circuit by this method is to follow the circuit diagram.
The images may be confusing.
  1. Solder pins 2 and 4 of IC socket together.
  2. Solder pins 6 and 7 of IC socket together.
  3. Solder the 33K resistor among pins 7 and 8 of IC socket.
  4. Solder the 100K resistor among pins 4 and 8 of IC socket.
  5. Solder the 100uF electrolyte capacitor among pins 1 (-) and 6 of IC socket.
  6. Solder the BC547 transistor among pins 1 (E) and 2 (C) of IC socket.
  7. Solder the TIP122 transistor among pins 3 (B) and 8 (C) of IC socket.
  8. Solder the 100nF ceramic capacitor among pins 1 and 5 of IC socket.
  9. Solder the 3.3uF electrolyte capacitor negative pole to pin 1 of IC socket.
  10. Solder one of the side legs of 50K potentiometer to 3.3uF electrolyte capacitor positive pole.
  11. Solder the middle leg of 50K potentiometer to BC547 transistor base pin (B).
  12. Solder the push button among pin 8 of IC socket and 3.3uF electrolyte capacitor positive pole with two wires.
  13. Solder the power supply to the pins 1 (-) and 8 (+) of IC socket.
  14. Solder a wire to TIP122 transistor emitter pin (E) as the motor positive pole.

Step 5: Making a PCB

Here is a good instructable that will guide you to make a PCB.
  1. Print the board images on an A6 glossy paper with a laser printer without scaling.
  2. Cut a piece of copper board in the size of printed board images.
  3. Clear the copper side of the board from oxides with sandpaper.
  4. Put the both sides of printed circuit on the board and fix them with paper tape.
  5. Put the board between some pieces of paper and press the hot iron (without steam) on it for a while. (BE CAREFUL: The hot iron may lead to firing of papers)
  6. Remove the printed circuit of the board.
  7. Soak board in a bowl of circuit board acid and wait till all the visible copper disappears. (BE CAREFUL: You are working with acid)
  8. Wash the board and clear it with sandpaper.
  9. Make holes with 1mm drill.
  10. Solder components on the board.
Here is the list of board components:
  • R1 = 33K Resistor
  • R2 = 100K Resistor
  • P = 50K Potentiometer
  • C1 = 3.3uF Electrolyte Capacitor
  • C2 = 100uF Electrolyte Capacitor
  • C3 = 100nF Ceramic Capacitor
  • U = 555 IC
  • Q1 = BC547 Transistor
  • Q2 = TIP122 Transistor
  • BTN = Simple Push Button
  • MOTOR = Small Motor

Step 6: The Motor

Attach a piece of plastic pipe (I cut it from a pen) to the end of the motor to avoid pressure on the motor shaft.
You need two strips of plastic approximately 9cm long to hold the motor, battery and circuit.
Attach and fasten the motor to the plastic strips with glue and some wire.
Solder the negative power supply to the one of the motor terminals, solder the positive power supply to the motor body and solder the wire coming from the TIP122 transistor emitter pin to the motor other terminal.
At last solder a 100nF ceramic capacitor and a 1N4148 diode among motor terminals to remove noise and back EMF. (The anode of the diode must be connected to the negative power supply.)

Step 7: LEDs Disk

Cut to circles from the foil to cover the plastic disk. The foils must not have an electrical contact so I made large hole around screws on one of the circles.
Place a wire into center hole of one disk and cover it with a foil circle, place the other plastic disk on them put some glue on the disk and cover it with other foil circle.
Then screw the disks together, the screws must be too loose to be able to place one leg of LEDs among the disks easily and too tight to LEDs be able to get stuck to the disk.
At last use glue to fasten loose nuts.

Step 8: Attaching Circuit and Battery

Attach the circuit to the other side of plastic strips with a screw and nuts.
Place the battery between motor and circuit and fasten it with tape if required.

Step 9: Final Assembly

Attach the plastic disks to the motor, note that the wire coming from the center of disks must be connected to the motor shaft.
Solder a 1N4007 diode kathode pin to the negative power supply and solder its anode to a wire that is in touch with the outer foil circle.
Roll the bubble bag around motor, battery and circuit to avoid impacts.

Step 10: Safety

The strewn LEDs may strike to your eyes, so put on safety glasses.
The thrown machine may strike to you head or breakable objects, so be careful where you throw the machine.

Step 11: Fire!

Adjust the potentiometer to start the motor on the air; it depends on how far you throw the machine.
Put the positive leg of LEDs among plastic disks in contact with inner foil circle and put the negative leg in contact with outer foil circle.
Press the push button and threw the machine to the air.

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